2022-09-08 14:15:06

by Pavel Tikhomirov

Subject: [PATCH v3 0/2] Introduce CABA helper process tree

CABA = Closest Alive Born Ancestor

In Linux process tree we reparent children of a dying process to the
reaper, thus loosing information in which subtree the child was
originally born. This information can be useful to CRIU to restore
process trees right.

The idea of CABA tree is to keep reference to the closest "born"
ancestor in the process tree. In simple case if our "born" parent dies
(completely unhashed) CABA would then point to its "born" parent - our
"born" grand-parent. So CABA is always referencing closest "born"
(grand-)*parent in available processes.

Please see "Add CABA tree to task_struct" for deeper explanation, and
"tests: Add CABA selftest" for a small test and an actual example for
which we might need CABA.

Probably the original problem of restoring process tree with complex
sessions can be resolved by allowing sessions copying, like we do for
process group, but I'm not sure if that would be too secure to do it,
and if there would not be another similar resource in future. So I
prefere CABA.

Also we can use CABA not only for CRIU for restoring processes, but in
normal life when processes detach CABA will help to understand from
which place in process tree they were originally started from sshd/crond
or something else.

Hope my idea is not completely insane =)

I plan to have a talk on LPC 2022 about it https://lpc.events/event/16/contributions/1241/

CC: Eric Biederman <[email protected]>
CC: Kees Cook <[email protected]>
CC: Alexander Viro <[email protected]>
CC: Ingo Molnar <[email protected]>
CC: Peter Zijlstra <[email protected]>
CC: Juri Lelli <[email protected]>
CC: Vincent Guittot <[email protected]>
CC: Dietmar Eggemann <[email protected]>
CC: Steven Rostedt <[email protected]>
CC: Ben Segall <[email protected]>
CC: Mel Gorman <[email protected]>
CC: Daniel Bristot de Oliveira <[email protected]>
CC: Valentin Schneider <[email protected]>
CC: Andrew Morton <[email protected]>
CC: [email protected]
CC: [email protected]
CC: [email protected]
CC: [email protected]
CC: [email protected]

Pavel Tikhomirov (2):
Add CABA tree to task_struct
tests: Add CABA selftest

arch/ia64/kernel/mca.c | 3 +
fs/exec.c | 1 +
fs/proc/array.c | 20 +
include/linux/sched.h | 7 +
init/init_task.c | 3 +
kernel/exit.c | 21 +
kernel/fork.c | 4 +
tools/testing/selftests/Makefile | 1 +
tools/testing/selftests/caba/.gitignore | 1 +
tools/testing/selftests/caba/Makefile | 7 +
tools/testing/selftests/caba/caba_test.c | 509 +++++++++++++++++++++++
tools/testing/selftests/caba/config | 1 +
12 files changed, 578 insertions(+)
create mode 100644 tools/testing/selftests/caba/.gitignore
create mode 100644 tools/testing/selftests/caba/Makefile
create mode 100644 tools/testing/selftests/caba/caba_test.c
create mode 100644 tools/testing/selftests/caba/config

--
2.37.1

2022-09-08 14:19:44

by Pavel Tikhomirov

Subject: [PATCH v3 2/2] tests: Add CABA selftest

This test creates a "tricky" example process tree where session leaders
of two sessions are children of pid namespace init, also they have their
own children, leader of session A has child with session B and leader
from session B has child with session A.

We check that Closest Alive Born Ancestor tree is right for this case.
This case illustrates how CABA tree helps to understand order of
creation between sessions.

CC: Eric Biederman <[email protected]>
CC: Kees Cook <[email protected]>
CC: Alexander Viro <[email protected]>
CC: Ingo Molnar <[email protected]>
CC: Peter Zijlstra <[email protected]>
CC: Juri Lelli <[email protected]>
CC: Vincent Guittot <[email protected]>
CC: Dietmar Eggemann <[email protected]>
CC: Steven Rostedt <[email protected]>
CC: Ben Segall <[email protected]>
CC: Mel Gorman <[email protected]>
CC: Daniel Bristot de Oliveira <[email protected]>
CC: Valentin Schneider <[email protected]>
CC: Andrew Morton <[email protected]>
CC: [email protected]
CC: [email protected]
CC: [email protected]
CC: [email protected]
CC: [email protected]

Signed-off-by: Pavel Tikhomirov <[email protected]>

--
v3: fix codding style
---
tools/testing/selftests/Makefile | 1 +
tools/testing/selftests/caba/.gitignore | 1 +
tools/testing/selftests/caba/Makefile | 7 +
tools/testing/selftests/caba/caba_test.c | 509 +++++++++++++++++++++++
tools/testing/selftests/caba/config | 1 +
5 files changed, 519 insertions(+)
create mode 100644 tools/testing/selftests/caba/.gitignore
create mode 100644 tools/testing/selftests/caba/Makefile
create mode 100644 tools/testing/selftests/caba/caba_test.c
create mode 100644 tools/testing/selftests/caba/config

diff --git a/tools/testing/selftests/Makefile b/tools/testing/selftests/Makefile
index c2064a35688b..d545bd9e3637 100644
--- a/tools/testing/selftests/Makefile
+++ b/tools/testing/selftests/Makefile
@@ -3,6 +3,7 @@ TARGETS += alsa
TARGETS += arm64
TARGETS += bpf
TARGETS += breakpoints
+TARGETS += caba
TARGETS += capabilities
TARGETS += cgroup
TARGETS += clone3
diff --git a/tools/testing/selftests/caba/.gitignore b/tools/testing/selftests/caba/.gitignore
new file mode 100644
index 000000000000..aa2c55b774e2
--- /dev/null
+++ b/tools/testing/selftests/caba/.gitignore
@@ -0,0 +1 @@
+caba_test
diff --git a/tools/testing/selftests/caba/Makefile b/tools/testing/selftests/caba/Makefile
new file mode 100644
index 000000000000..4260145c3747
--- /dev/null
+++ b/tools/testing/selftests/caba/Makefile
@@ -0,0 +1,7 @@
+# SPDX-License-Identifier: GPL-2.0
+# Makefile for caba selftests.
+CFLAGS = -g -I../../../../usr/include/ -Wall -O2
+
+TEST_GEN_FILES += caba_test
+
+include ../lib.mk
diff --git a/tools/testing/selftests/caba/caba_test.c b/tools/testing/selftests/caba/caba_test.c
new file mode 100644
index 000000000000..a89c4b96393b
--- /dev/null
+++ b/tools/testing/selftests/caba/caba_test.c
@@ -0,0 +1,509 @@
+// SPDX-License-Identifier: GPL-2.0
+#define _GNU_SOURCE
+
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sched.h>
+#include <fcntl.h>
+#include <limits.h>
+#include <sys/mman.h>
+#include <sys/wait.h>
+#include <sys/prctl.h>
+#include <sys/socket.h>
+#include <sys/mount.h>
+#include <sys/user.h>
+
+#include "../kselftest_harness.h"
+
+#ifndef CLONE_NEWPID
+#define CLONE_NEWPID 0x20000000 /* New pid namespace */
+#endif
+
+/* Attempt to de-conflict with the selftests tree. */
+#ifndef SKIP
+#define SKIP(s, ...) XFAIL(s, ##__VA_ARGS__)
+#endif
+
+struct process {
+ pid_t pid;
+ pid_t real;
+ pid_t caba;
+ int sks[2];
+ int dead;
+};
+
+struct process *processes;
+int nr_processes = 8;
+int current;
+
+static void cleanup(void)
+{
+ kill(processes[0].pid, SIGKILL);
+ /* It's enough to kill pidns init for others to die */
+ kill(processes[1].pid, SIGKILL);
+}
+
+enum commands {
+ TEST_FORK,
+ TEST_WAIT,
+ TEST_SUBREAPER,
+ TEST_SETSID,
+ TEST_DIE,
+ /* unused */
+ TEST_GETSID,
+ TEST_SETNS,
+ TEST_SETPGID,
+ TEST_GETPGID,
+ TEST_GETPPID,
+};
+
+struct command {
+ enum commands cmd;
+ int arg1;
+ int arg2;
+};
+
+static void handle_command(void);
+
+static void mainloop(void)
+{
+ while (1)
+ handle_command();
+}
+
+#define CLONE_STACK_SIZE 4096
+#define __stack_aligned__ __attribute__((aligned(16)))
+/* All arguments should be above stack, because it grows down */
+struct clone_args {
+ char stack[CLONE_STACK_SIZE] __stack_aligned__;
+ char stack_ptr[0];
+ int id;
+};
+
+static int get_real_pid(void)
+{
+ char buf[11];
+ int ret;
+
+ ret = readlink("/proc/self", buf, sizeof(buf)-1);
+ if (ret <= 0) {
+ fprintf(stderr, "%d: readlink /proc/self :%m", current);
+ return -1;
+ }
+ buf[ret] = '\0';
+
+ processes[current].real = atoi(buf);
+ return 0;
+}
+
+static int clone_func(void *_arg)
+{
+ struct clone_args *args = (struct clone_args *) _arg;
+
+ current = args->id;
+
+ if (get_real_pid())
+ exit(1);
+
+ printf("%3d: Hello. My pid is %d\n", args->id, getpid());
+ mainloop();
+ exit(0);
+}
+
+static int make_child(int id, int flags)
+{
+ struct clone_args args;
+ pid_t cid;
+
+ args.id = id;
+
+ cid = clone(clone_func, args.stack_ptr,
+ flags | SIGCHLD, &args);
+
+ if (cid < 0)
+ fprintf(stderr, "clone(%d, %d) :%m", id, flags);
+
+ processes[id].pid = cid;
+
+ return cid;
+}
+
+static int open_proc(void)
+{
+ int fd;
+ char proc_mountpoint[] = "/tmp/.caba_test.proc.XXXXXX";
+
+ if (mkdtemp(proc_mountpoint) == NULL) {
+ fprintf(stderr, "mkdtemp failed %s :%m\n", proc_mountpoint);
+ return -1;
+ }
+
+ if (mount("proc", proc_mountpoint, "proc",
+ MS_MGC_VAL | MS_NOSUID | MS_NOEXEC | MS_NODEV, NULL)) {
+ fprintf(stderr, "mount proc failed :%m\n");
+ rmdir(proc_mountpoint);
+ return -1;
+ }
+
+ fd = open(proc_mountpoint, O_RDONLY | O_DIRECTORY, 0);
+ if (fd < 0)
+ fprintf(stderr, "can't open proc :%m\n");
+
+ if (umount2(proc_mountpoint, MNT_DETACH)) {
+ fprintf(stderr, "can't umount proc :%m\n");
+ goto err_close;
+ }
+
+ if (rmdir(proc_mountpoint)) {
+ fprintf(stderr, "can't remove tmp dir :%m\n");
+ goto err_close;
+ }
+
+ return fd;
+err_close:
+ if (fd >= 0)
+ close(fd);
+ return -1;
+}
+
+static int open_pidns(int pid)
+{
+ int proc, fd;
+ char pidns_path[PATH_MAX];
+
+ proc = open_proc();
+ if (proc < 0) {
+ fprintf(stderr, "open proc\n");
+ return -1;
+ }
+
+ sprintf(pidns_path, "%d/ns/pid", pid);
+ fd = openat(proc, pidns_path, O_RDONLY);
+ if (fd == -1)
+ fprintf(stderr, "open pidns fd\n");
+
+ close(proc);
+ return fd;
+}
+
+static int setns_pid(int pid, int nstype)
+{
+ int pidns, ret;
+
+ pidns = open_pidns(pid);
+ if (pidns < 0)
+ return -1;
+
+ ret = setns(pidns, nstype);
+ if (ret == -1)
+ fprintf(stderr, "setns :%m\n");
+
+ close(pidns);
+ return ret;
+}
+
+static void handle_command(void)
+{
+ int sk = processes[current].sks[0], ret, status = 0;
+ struct command cmd;
+
+ ret = read(sk, &cmd, sizeof(cmd));
+ if (ret != sizeof(cmd)) {
+ fprintf(stderr, "Unable to get command :%m\n");
+ goto err;
+ }
+
+ switch (cmd.cmd) {
+ case TEST_FORK:
+ {
+ pid_t pid;
+
+ pid = make_child(cmd.arg1, cmd.arg2);
+ if (pid == -1) {
+ status = -1;
+ goto err;
+ }
+
+ printf("%3d: fork(%d, %x) = %d\n",
+ current, cmd.arg1, cmd.arg2, pid);
+ processes[cmd.arg1].pid = pid;
+ }
+ break;
+ case TEST_WAIT:
+ printf("%3d: wait(%d) = %d\n", current,
+ cmd.arg1, processes[cmd.arg1].pid);
+
+ if (waitpid(processes[cmd.arg1].pid, NULL, 0) == -1) {
+ fprintf(stderr, "waitpid(%d) :%m\n", processes[cmd.arg1].pid);
+ status = -1;
+ }
+ break;
+ case TEST_SUBREAPER:
+ printf("%3d: subreaper(%d)\n", current, cmd.arg1);
+ if (prctl(PR_SET_CHILD_SUBREAPER, cmd.arg1, 0, 0, 0) == -1) {
+ fprintf(stderr, "PR_SET_CHILD_SUBREAPER :%m\n");
+ status = -1;
+ }
+ break;
+ case TEST_SETSID:
+ printf("%3d: setsid()\n", current);
+ if (setsid() == -1) {
+ fprintf(stderr, "setsid :%m\n");
+ status = -1;
+ }
+ break;
+ case TEST_GETSID:
+ printf("%3d: getsid()\n", current);
+ status = getsid(getpid());
+ if (status == -1)
+ fprintf(stderr, "getsid :%m\n");
+ break;
+ case TEST_SETPGID:
+ printf("%3d: setpgid(%d, %d)\n", current, cmd.arg1, cmd.arg2);
+ if (setpgid(processes[cmd.arg1].pid, processes[cmd.arg2].pid) == -1) {
+ fprintf(stderr, "setpgid :%m\n");
+ status = -1;
+ }
+ break;
+ case TEST_GETPGID:
+ printf("%3d: getpgid()\n", current);
+ status = getpgid(0);
+ if (status == -1)
+ fprintf(stderr, "getpgid :%m\n");
+ break;
+ case TEST_GETPPID:
+ printf("%3d: getppid()\n", current);
+ status = getppid();
+ if (status == -1)
+ fprintf(stderr, "getppid :%m\n");
+ break;
+ case TEST_SETNS:
+ printf("%3d: setns(%d, %d) = %d\n", current,
+ cmd.arg1, cmd.arg2, processes[cmd.arg1].pid);
+ setns_pid(processes[cmd.arg1].pid, cmd.arg2);
+
+ break;
+ case TEST_DIE:
+ printf("%3d: die()\n", current);
+ processes[current].dead = 1;
+ shutdown(sk, SHUT_RDWR);
+ exit(0);
+ }
+
+ ret = write(sk, &status, sizeof(status));
+ if (ret != sizeof(status)) {
+ fprintf(stderr, "Unable to answer :%m\n");
+ goto err;
+ }
+
+ if (status < 0)
+ goto err;
+
+ return;
+err:
+ shutdown(sk, SHUT_RDWR);
+ exit(1);
+}
+
+static int send_command(int id, enum commands op, int arg1, int arg2)
+{
+ int sk = processes[id].sks[1], ret, status;
+ struct command cmd = {op, arg1, arg2};
+
+ if (op == TEST_FORK) {
+ if (processes[arg1].pid) {
+ fprintf(stderr, "%d is busy :%m\n", arg1);
+ return -1;
+ }
+ }
+
+ ret = write(sk, &cmd, sizeof(cmd));
+ if (ret != sizeof(cmd)) {
+ fprintf(stderr, "Unable to send command :%m\n");
+ goto err;
+ }
+
+ status = 0;
+ ret = read(sk, &status, sizeof(status));
+ if (ret != sizeof(status) && !(status == 0 && op == TEST_DIE)) {
+ fprintf(stderr, "Unable to get answer :%m\n");
+ goto err;
+ }
+
+ if (status != -1 && (op == TEST_GETSID || op == TEST_GETPGID || op == TEST_GETPPID))
+ return status;
+
+ if (status) {
+ fprintf(stderr, "The command(%d, %d, %d) failed :%m\n", op, arg1, arg2);
+ goto err;
+ }
+
+ return 0;
+err:
+ cleanup();
+ exit(1);
+}
+
+static int get_caba(int pid, int *caba)
+{
+ char buf[64], *str;
+ FILE *fp;
+ size_t n;
+
+ if (!pid)
+ snprintf(buf, sizeof(buf), "/proc/self/status");
+ else
+ snprintf(buf, sizeof(buf), "/proc/%d/status", pid);
+
+ fp = fopen(buf, "r");
+ if (!fp) {
+ perror("fopen");
+ return -1;
+ }
+
+ str = NULL;
+ while (getline(&str, &n, fp) != -1) {
+ if (strncmp(str, "NScaba:", 7) == 0) {
+ if (str[7] == '\0') {
+ *caba = 0;
+ } else {
+ if (sscanf(str+7, "%d", caba) != 1) {
+ perror("sscanf");
+ goto err;
+ }
+ }
+
+ fclose(fp);
+ free(str);
+ return 0;
+ }
+ }
+err:
+ free(str);
+ fclose(fp);
+ return -1;
+}
+
+static bool caba_supported(void)
+{
+ int caba;
+
+ return !get_caba(0, &caba);
+}
+
+FIXTURE(caba) {
+};
+
+FIXTURE_SETUP(caba)
+{
+ bool ret;
+
+ ret = caba_supported();
+ ASSERT_GE(ret, 0);
+ if (!ret)
+ SKIP(return, "CABA is not supported");
+}
+
+FIXTURE_TEARDOWN(caba)
+{
+ bool ret;
+
+ ret = caba_supported();
+ ASSERT_GE(ret, 0);
+ if (!ret)
+ SKIP(return, "CABA is not supported");
+
+ cleanup();
+}
+
+TEST_F(caba, complex_sessions)
+{
+ int ret, i, pid, caba;
+
+ ret = caba_supported();
+ ASSERT_GE(ret, 0);
+ if (!ret)
+ SKIP(return, "CABA is not supported");
+
+ processes = mmap(NULL, PAGE_SIZE,
+ PROT_WRITE | PROT_READ, MAP_SHARED | MAP_ANONYMOUS,
+ 0, 0);
+ ASSERT_NE(processes, MAP_FAILED);
+ for (i = 0; i < nr_processes; i++) {
+ ret = socketpair(PF_UNIX, SOCK_STREAM, 0, processes[i].sks);
+ ASSERT_EQ(ret, 0);
+ }
+
+ /*
+ * Create init:
+ * (pid, sid)
+ * (1, 1)
+ */
+ pid = make_child(0, 0); ASSERT_GT(pid, 0);
+ ret = send_command(0, TEST_FORK, 1, CLONE_NEWPID);
+ ASSERT_EQ(ret, 0);
+ ret = send_command(1, TEST_SETSID, 0, 0);
+ ASSERT_EQ(ret, 0);
+
+ /*
+ * Create sequence of processes from one session:
+ * (pid, sid)
+ * (1, 1)---(2, 2)---(3, 2)---(4, 2)---(5, 2)
+ */
+ ret = send_command(1, TEST_FORK, 2, 0); ASSERT_EQ(ret, 0);
+ ret = send_command(2, TEST_SETSID, 0, 0); ASSERT_EQ(ret, 0);
+ ret = send_command(2, TEST_FORK, 3, 0); ASSERT_EQ(ret, 0);
+ ret = send_command(3, TEST_FORK, 4, 0); ASSERT_EQ(ret, 0);
+ ret = send_command(4, TEST_FORK, 5, 0); ASSERT_EQ(ret, 0);
+ /*
+ * Create another session in the middle of first one:
+ * (pid, sid)
+ * (1, 1)---(2, 2)---(3, 2)---(4, 4)-+-(5, 2)
+ * `-(6, 4)---(7, 4)
+ */
+ ret = send_command(4, TEST_SETSID, 0, 0); ASSERT_EQ(ret, 0);
+ ret = send_command(4, TEST_FORK, 6, 0); ASSERT_EQ(ret, 0);
+ ret = send_command(6, TEST_FORK, 7, 0); ASSERT_EQ(ret, 0);
+
+ /*
+ * Kill 6 while having 2 as child-sub-reaper:
+ * (pid, sid)
+ * (1, 1)---(2, 2)---(3, 2)---(4, 4)-+-(5, 2)
+ * `-(7, 4)
+ */
+ ret = send_command(2, TEST_SUBREAPER, 1, 0); ASSERT_EQ(ret, 0);
+ ret = send_command(6, TEST_DIE, 0, 0); ASSERT_EQ(ret, 0);
+ ret = send_command(4, TEST_WAIT, 6, 0); ASSERT_EQ(ret, 0);
+ ret = send_command(2, TEST_SUBREAPER, 0, 0); ASSERT_EQ(ret, 0);
+
+ /*
+ * Kill 3:
+ * (pid, sid)
+ * (1, 1)-+-(2, 2)---(7, 4)
+ * `-(4, 4)---(5, 2)
+ * note: This is a "tricky" session tree example where it's not obvious
+ * whether sid 2 was created first or sid 4 when creating the tree.
+ */
+ ret = send_command(3, TEST_DIE, 0, 0); ASSERT_EQ(ret, 0);
+ ret = send_command(2, TEST_WAIT, 3, 0); ASSERT_EQ(ret, 0);
+
+ /*
+ * CABA tree for this would be:
+ * (pid, sid)
+ * (1, 1)---(2, 2)---(4, 4)-+-(5, 2)
+ * `-(7, 4)
+ * note: CABA allows us to understand that session 2 was created first.
+ */
+ ret = get_caba(processes[2].real, &caba);
+ ASSERT_EQ(ret, 0); ASSERT_EQ(caba, processes[1].real);
+ ret = get_caba(processes[4].real, &caba);
+ ASSERT_EQ(ret, 0); ASSERT_EQ(caba, processes[2].real);
+ ret = get_caba(processes[5].real, &caba);
+ ASSERT_EQ(ret, 0); ASSERT_EQ(caba, processes[4].real);
+ ret = get_caba(processes[7].real, &caba);
+ ASSERT_EQ(ret, 0); ASSERT_EQ(caba, processes[4].real);
+}
+
+TEST_HARNESS_MAIN
diff --git a/tools/testing/selftests/caba/config b/tools/testing/selftests/caba/config
new file mode 100644
index 000000000000..eae7bdaa3790
--- /dev/null
+++ b/tools/testing/selftests/caba/config
@@ -0,0 +1 @@
+CONFIG_PID_NS=y
--
2.37.1

2022-09-08 14:36:59

by Pavel Tikhomirov

Subject: [PATCH v3 1/2] Add CABA tree to task_struct

In linux after parent (father) process dies, children processes are
moved (reparented) to a reaper process. Roughly speaking:

1) If father has other yet alive thread, this thread would be a reaper.

2) Else if there is father's ancestor (with no pidns level change in the
middle), which has PR_SET_CHILD_SUBREAPER set, this ancestor would be a
reaper.

3) Else father's pidns init would be a reaper for fathers children.

The problem with this for CRIU is that when CRIU comes to dump processes
it does not know the order in which processes and their resources were
created. And processes can have resources which a) can only be inherited
when we clone processes, b) can only be created by specific processes
and c) are shared between several processes (the example of such a
resource is process session). For such resources CRIU restore would need
to re-invent such order of process creation which at the same time
creates the desired process tree topology and allows to inherit all
resources right.

When process reparenting involves child-sub-reapers one can drastically
mix processes in process tree so that it is not obvious how to restore
everything right.

So this is what we came up with to help CRIU to overcome this problem:

CABA = Closest Alive Born Ancestor
CABD = Closest Alive Born Descendant

We want to put processes in one more tree - CABA tree. This tree is not
affecting reparenting or process creation in any way except for
providing a new information to CRIU so that we can understand from where
the reparented child had reparented, though original father is already
dead and probably a fathers father too, we can still have information
about the process which is still alive and was originally a parent of
process sequence (of already dead processes) which lead to us - CABA.

CC: Eric Biederman <[email protected]>
CC: Kees Cook <[email protected]>
CC: Alexander Viro <[email protected]>
CC: Ingo Molnar <[email protected]>
CC: Peter Zijlstra <[email protected]>
CC: Juri Lelli <[email protected]>
CC: Vincent Guittot <[email protected]>
CC: Dietmar Eggemann <[email protected]>
CC: Steven Rostedt <[email protected]>
CC: Ben Segall <[email protected]>
CC: Mel Gorman <[email protected]>
CC: Daniel Bristot de Oliveira <[email protected]>
CC: Valentin Schneider <[email protected]>
CC: Andrew Morton <[email protected]>
CC: [email protected]
CC: [email protected]
CC: [email protected]
CC: [email protected]
CC: [email protected]

Signed-off-by: Pavel Tikhomirov <[email protected]>

--
v2: fix unused variables reported-by: kernel test robot <[email protected]>
v3: - on fork set caba to current, so that caba is always a process
which had initiated our creation, even for CLONE_PARENT case
- move caba update to a later stage (to __unhash_process), so that
zombies can be somebodies caba until fully released
---
arch/ia64/kernel/mca.c | 3 +++
fs/exec.c | 1 +
fs/proc/array.c | 20 ++++++++++++++++++++
include/linux/sched.h | 7 +++++++
init/init_task.c | 3 +++
kernel/exit.c | 21 +++++++++++++++++++++
kernel/fork.c | 4 ++++
7 files changed, 59 insertions(+)

diff --git a/arch/ia64/kernel/mca.c b/arch/ia64/kernel/mca.c
index c62a66710ad6..5e561994cff7 100644
--- a/arch/ia64/kernel/mca.c
+++ b/arch/ia64/kernel/mca.c
@@ -1793,6 +1793,9 @@ format_mca_init_stack(void *mca_data, unsigned long offset,
p->parent = p->real_parent = p->group_leader = p;
INIT_LIST_HEAD(&p->children);
INIT_LIST_HEAD(&p->sibling);
+ p->caba = p;
+ INIT_LIST_HEAD(&p->cabds);
+ INIT_LIST_HEAD(&p->cabd);
strncpy(p->comm, type, sizeof(p->comm)-1);
}

diff --git a/fs/exec.c b/fs/exec.c
index 9a5ca7b82bfc..8caaa03739ab 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -1139,6 +1139,7 @@ static int de_thread(struct task_struct *tsk)

list_replace_rcu(&leader->tasks, &tsk->tasks);
list_replace_init(&leader->sibling, &tsk->sibling);
+ list_replace_init(&leader->cabd, &tsk->cabd);

tsk->group_leader = tsk;
leader->group_leader = tsk;
diff --git a/fs/proc/array.c b/fs/proc/array.c
index 99fcbfda8e25..5fd70aebd52d 100644
--- a/fs/proc/array.c
+++ b/fs/proc/array.c
@@ -154,11 +154,28 @@ static inline void task_state(struct seq_file *m, struct pid_namespace *ns,
const struct cred *cred;
pid_t ppid, tpid = 0, tgid, ngid;
unsigned int max_fds = 0;
+#ifdef CONFIG_PID_NS
+ struct task_struct *caba;
+ struct pid *caba_pid;
+ int caba_level = 0;
+ pid_t caba_pids[MAX_PID_NS_LEVEL] = {};
+#endif

rcu_read_lock();
ppid = pid_alive(p) ?
task_tgid_nr_ns(rcu_dereference(p->real_parent), ns) : 0;

+#ifdef CONFIG_PID_NS
+ caba = rcu_dereference(p->caba);
+ caba_pid = get_task_pid(caba, PIDTYPE_PID);
+ if (caba_pid) {
+ caba_level = caba_pid->level;
+ for (g = ns->level; g <= caba_level; g++)
+ caba_pids[g] = task_pid_nr_ns(caba, caba_pid->numbers[g].ns);
+ put_pid(caba_pid);
+ }
+#endif
+
tracer = ptrace_parent(p);
if (tracer)
tpid = task_pid_nr_ns(tracer, ns);
@@ -217,6 +234,9 @@ static inline void task_state(struct seq_file *m, struct pid_namespace *ns,
seq_puts(m, "\nNSsid:");
for (g = ns->level; g <= pid->level; g++)
seq_put_decimal_ull(m, "\t", task_session_nr_ns(p, pid->numbers[g].ns));
+ seq_puts(m, "\nNScaba:");
+ for (g = ns->level; g <= caba_level; g++)
+ seq_put_decimal_ull(m, "\t", caba_pids[g]);
#endif
seq_putc(m, '\n');
}
diff --git a/include/linux/sched.h b/include/linux/sched.h
index e7b2f8a5c711..b30a2ccf1180 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -975,6 +975,13 @@ struct task_struct {
struct list_head sibling;
struct task_struct *group_leader;

+ /* Closest Alive Born Ancestor process: */
+ struct task_struct __rcu *caba;
+
+ /* Closest Alive Born Descendants list: */
+ struct list_head cabds;
+ struct list_head cabd;
+
/*
* 'ptraced' is the list of tasks this task is using ptrace() on.
*
diff --git a/init/init_task.c b/init/init_task.c
index ff6c4b9bfe6b..439da3b04dde 100644
--- a/init/init_task.c
+++ b/init/init_task.c
@@ -109,6 +109,9 @@ struct task_struct init_task
.children = LIST_HEAD_INIT(init_task.children),
.sibling = LIST_HEAD_INIT(init_task.sibling),
.group_leader = &init_task,
+ .caba = &init_task,
+ .cabds = LIST_HEAD_INIT(init_task.cabds),
+ .cabd = LIST_HEAD_INIT(init_task.cabd),
RCU_POINTER_INITIALIZER(real_cred, &init_cred),
RCU_POINTER_INITIALIZER(cred, &init_cred),
.comm = INIT_TASK_COMM,
diff --git a/kernel/exit.c b/kernel/exit.c
index 84021b24f79e..32e4a380861d 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -71,9 +71,29 @@
#include <asm/unistd.h>
#include <asm/mmu_context.h>

+static void forget_caba(struct task_struct *caba)
+{
+ struct task_struct *p, *t, *new_caba;
+
+ if (list_empty(&caba->cabds))
+ return;
+
+ if (!thread_group_leader(caba))
+ new_caba = caba->group_leader;
+ else
+ new_caba = caba->caba;
+
+ list_for_each_entry(p, &caba->cabds, cabd) {
+ for_each_thread(p, t)
+ RCU_INIT_POINTER(t->caba, new_caba);
+ }
+ list_splice_tail_init(&caba->cabds, &new_caba->cabds);
+}
+
static void __unhash_process(struct task_struct *p, bool group_dead)
{
nr_threads--;
+ forget_caba(p);
detach_pid(p, PIDTYPE_PID);
if (group_dead) {
detach_pid(p, PIDTYPE_TGID);
@@ -82,6 +102,7 @@ static void __unhash_process(struct task_struct *p, bool group_dead)

list_del_rcu(&p->tasks);
list_del_init(&p->sibling);
+ list_del_init(&p->cabd);
__this_cpu_dec(process_counts);
}
list_del_rcu(&p->thread_group);
diff --git a/kernel/fork.c b/kernel/fork.c
index 90c85b17bf69..a14ee9f1acb1 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -2139,6 +2139,8 @@ static __latent_entropy struct task_struct *copy_process(
p->flags |= PF_FORKNOEXEC;
INIT_LIST_HEAD(&p->children);
INIT_LIST_HEAD(&p->sibling);
+ INIT_LIST_HEAD(&p->cabds);
+ INIT_LIST_HEAD(&p->cabd);
rcu_copy_process(p);
p->vfork_done = NULL;
spin_lock_init(&p->alloc_lock);
@@ -2402,6 +2404,7 @@ static __latent_entropy struct task_struct *copy_process(
p->parent_exec_id = current->self_exec_id;
p->exit_signal = args->exit_signal;
}
+ p->caba = current;

klp_copy_process(p);

@@ -2455,6 +2458,7 @@ static __latent_entropy struct task_struct *copy_process(
p->signal->has_child_subreaper = p->real_parent->signal->has_child_subreaper ||
p->real_parent->signal->is_child_subreaper;
list_add_tail(&p->sibling, &p->real_parent->children);
+ list_add_tail(&p->cabd, &p->caba->cabds);
list_add_tail_rcu(&p->tasks, &init_task.tasks);
attach_pid(p, PIDTYPE_TGID);
attach_pid(p, PIDTYPE_PGID);
--
2.37.1

2022-09-08 22:19:12

by kernel test robot

Subject: Re: [PATCH v3 1/2] Add CABA tree to task_struct

Hi Pavel,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on shuah-kselftest/next]
[also build test WARNING on kees/for-next/execve tip/sched/core linus/master v6.0-rc4 next-20220908]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url: https://github.com/intel-lab-lkp/linux/commits/Pavel-Tikhomirov/Introduce-CABA-helper-process-tree/20220908-220639
base: https://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest.git next
config: s390-randconfig-s043-20220907 (https://download.01.org/0day-ci/archive/20220909/[email protected]/config)
compiler: s390-linux-gcc (GCC) 12.1.0
reproduce:
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# apt-get install sparse
# sparse version: v0.6.4-39-gce1a6720-dirty
# https://github.com/intel-lab-lkp/linux/commit/17a897a33137d4f49f99c8be8d619f6f711fccdb
git remote add linux-review https://github.com/intel-lab-lkp/linux
git fetch --no-tags linux-review Pavel-Tikhomirov/Introduce-CABA-helper-process-tree/20220908-220639
git checkout 17a897a33137d4f49f99c8be8d619f6f711fccdb
# save the config file
mkdir build_dir && cp config build_dir/.config
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__' O=build_dir ARCH=s390 SHELL=/bin/bash

If you fix the issue, kindly add following tag where applicable
Reported-by: kernel test robot <[email protected]>

sparse warnings: (new ones prefixed by >>)
kernel/fork.c:1307:22: sparse: sparse: incorrect type in assignment (different address spaces) @@ expected struct file *[assigned] old_exe_file @@ got struct file [noderef] __rcu *[assigned] __ret @@
kernel/fork.c:1307:22: sparse: expected struct file *[assigned] old_exe_file
kernel/fork.c:1307:22: sparse: got struct file [noderef] __rcu *[assigned] __ret
kernel/fork.c:1638:38: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected struct refcount_struct [usertype] *r @@ got struct refcount_struct [noderef] __rcu * @@
kernel/fork.c:1638:38: sparse: expected struct refcount_struct [usertype] *r
kernel/fork.c:1638:38: sparse: got struct refcount_struct [noderef] __rcu *
kernel/fork.c:1647:31: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected struct spinlock [usertype] *lock @@ got struct spinlock [noderef] __rcu * @@
kernel/fork.c:1647:31: sparse: expected struct spinlock [usertype] *lock
kernel/fork.c:1647:31: sparse: got struct spinlock [noderef] __rcu *
kernel/fork.c:1648:9: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected void const * @@ got struct k_sigaction [noderef] __rcu * @@
kernel/fork.c:1648:9: sparse: expected void const *
kernel/fork.c:1648:9: sparse: got struct k_sigaction [noderef] __rcu *
kernel/fork.c:1648:9: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected void const * @@ got struct k_sigaction [noderef] __rcu * @@
kernel/fork.c:1648:9: sparse: expected void const *
kernel/fork.c:1648:9: sparse: got struct k_sigaction [noderef] __rcu *
kernel/fork.c:1648:9: sparse: sparse: incorrect type in argument 2 (different address spaces) @@ expected void const * @@ got struct k_sigaction [noderef] __rcu * @@
kernel/fork.c:1648:9: sparse: expected void const *
kernel/fork.c:1648:9: sparse: got struct k_sigaction [noderef] __rcu *
kernel/fork.c:1649:33: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected struct spinlock [usertype] *lock @@ got struct spinlock [noderef] __rcu * @@
kernel/fork.c:1649:33: sparse: expected struct spinlock [usertype] *lock
kernel/fork.c:1649:33: sparse: got struct spinlock [noderef] __rcu *
kernel/fork.c:1742:9: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected struct arch_spinlock_t [usertype] *lp @@ got struct arch_spinlock_t [noderef] __rcu * @@
kernel/fork.c:1742:9: sparse: expected struct arch_spinlock_t [usertype] *lp
kernel/fork.c:1742:9: sparse: got struct arch_spinlock_t [noderef] __rcu *
kernel/fork.c:2077:31: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected struct spinlock [usertype] *lock @@ got struct spinlock [noderef] __rcu * @@
kernel/fork.c:2077:31: sparse: expected struct spinlock [usertype] *lock
kernel/fork.c:2077:31: sparse: got struct spinlock [noderef] __rcu *
kernel/fork.c:2081:33: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected struct spinlock [usertype] *lock @@ got struct spinlock [noderef] __rcu * @@
kernel/fork.c:2081:33: sparse: expected struct spinlock [usertype] *lock
kernel/fork.c:2081:33: sparse: got struct spinlock [noderef] __rcu *
kernel/fork.c:2403:32: sparse: sparse: incorrect type in assignment (different address spaces) @@ expected struct task_struct [noderef] __rcu *real_parent @@ got struct task_struct * @@
kernel/fork.c:2403:32: sparse: expected struct task_struct [noderef] __rcu *real_parent
kernel/fork.c:2403:32: sparse: got struct task_struct *
>> kernel/fork.c:2407:17: sparse: sparse: incorrect type in assignment (different address spaces) @@ expected struct task_struct [noderef] __rcu *caba @@ got struct task_struct * @@
kernel/fork.c:2407:17: sparse: expected struct task_struct [noderef] __rcu *caba
kernel/fork.c:2407:17: sparse: got struct task_struct *
kernel/fork.c:2413:27: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected struct spinlock [usertype] *lock @@ got struct spinlock [noderef] __rcu * @@
kernel/fork.c:2413:27: sparse: expected struct spinlock [usertype] *lock
kernel/fork.c:2413:27: sparse: got struct spinlock [noderef] __rcu *
kernel/fork.c:2460:54: sparse: sparse: incorrect type in argument 2 (different address spaces) @@ expected struct list_head *head @@ got struct list_head [noderef] __rcu * @@
kernel/fork.c:2460:54: sparse: expected struct list_head *head
kernel/fork.c:2460:54: sparse: got struct list_head [noderef] __rcu *
kernel/fork.c:2461:51: sparse: sparse: incorrect type in argument 2 (different address spaces) @@ expected struct list_head *head @@ got struct list_head [noderef] __rcu * @@
kernel/fork.c:2461:51: sparse: expected struct list_head *head
kernel/fork.c:2461:51: sparse: got struct list_head [noderef] __rcu *
kernel/fork.c:2482:29: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected struct spinlock [usertype] *lock @@ got struct spinlock [noderef] __rcu * @@
kernel/fork.c:2482:29: sparse: expected struct spinlock [usertype] *lock
kernel/fork.c:2482:29: sparse: got struct spinlock [noderef] __rcu *
kernel/fork.c:2503:29: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected struct spinlock [usertype] *lock @@ got struct spinlock [noderef] __rcu * @@
kernel/fork.c:2503:29: sparse: expected struct spinlock [usertype] *lock
kernel/fork.c:2503:29: sparse: got struct spinlock [noderef] __rcu *
kernel/fork.c:2530:28: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected struct sighand_struct *sighand @@ got struct sighand_struct [noderef] __rcu *sighand @@
kernel/fork.c:2530:28: sparse: expected struct sighand_struct *sighand
kernel/fork.c:2530:28: sparse: got struct sighand_struct [noderef] __rcu *sighand
kernel/fork.c:2559:31: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected struct spinlock [usertype] *lock @@ got struct spinlock [noderef] __rcu * @@
kernel/fork.c:2559:31: sparse: expected struct spinlock [usertype] *lock
kernel/fork.c:2559:31: sparse: got struct spinlock [noderef] __rcu *
kernel/fork.c:2561:33: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected struct spinlock [usertype] *lock @@ got struct spinlock [noderef] __rcu * @@
kernel/fork.c:2561:33: sparse: expected struct spinlock [usertype] *lock
kernel/fork.c:2561:33: sparse: got struct spinlock [noderef] __rcu *
kernel/fork.c:2997:24: sparse: sparse: incorrect type in assignment (different address spaces) @@ expected struct task_struct *[assigned] parent @@ got struct task_struct [noderef] __rcu *real_parent @@
kernel/fork.c:2997:24: sparse: expected struct task_struct *[assigned] parent
kernel/fork.c:2997:24: sparse: got struct task_struct [noderef] __rcu *real_parent
kernel/fork.c:3078:43: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected struct refcount_struct const [usertype] *r @@ got struct refcount_struct [noderef] __rcu * @@
kernel/fork.c:3078:43: sparse: expected struct refcount_struct const [usertype] *r
kernel/fork.c:3078:43: sparse: got struct refcount_struct [noderef] __rcu *
kernel/fork.c:2122:22: sparse: sparse: dereference of noderef expression
kernel/fork.c: note: in included file (through arch/s390/include/asm/stacktrace.h, arch/s390/include/asm/perf_event.h, include/linux/perf_event.h, ...):
include/linux/ptrace.h:210:45: sparse: sparse: incorrect type in argument 2 (different address spaces) @@ expected struct task_struct *new_parent @@ got struct task_struct [noderef] __rcu *parent @@
include/linux/ptrace.h:210:45: sparse: expected struct task_struct *new_parent
include/linux/ptrace.h:210:45: sparse: got struct task_struct [noderef] __rcu *parent
include/linux/ptrace.h:210:62: sparse: sparse: incorrect type in argument 3 (different address spaces) @@ expected struct cred const *ptracer_cred @@ got struct cred const [noderef] __rcu *ptracer_cred @@
include/linux/ptrace.h:210:62: sparse: expected struct cred const *ptracer_cred
include/linux/ptrace.h:210:62: sparse: got struct cred const [noderef] __rcu *ptracer_cred
kernel/fork.c:2458:59: sparse: sparse: dereference of noderef expression
kernel/fork.c:2459:59: sparse: sparse: dereference of noderef expression
--
>> kernel/exit.c:84:26: sparse: sparse: incorrect type in assignment (different address spaces) @@ expected struct task_struct *[assigned] new_caba @@ got struct task_struct [noderef] __rcu *caba @@
kernel/exit.c:84:26: sparse: expected struct task_struct *[assigned] new_caba
kernel/exit.c:84:26: sparse: got struct task_struct [noderef] __rcu *caba
kernel/exit.c:302:37: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected struct task_struct *tsk @@ got struct task_struct [noderef] __rcu *real_parent @@
kernel/exit.c:302:37: sparse: expected struct task_struct *tsk
kernel/exit.c:302:37: sparse: got struct task_struct [noderef] __rcu *real_parent
kernel/exit.c:305:32: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected struct task_struct *task @@ got struct task_struct [noderef] __rcu *real_parent @@
kernel/exit.c:305:32: sparse: expected struct task_struct *task
kernel/exit.c:305:32: sparse: got struct task_struct [noderef] __rcu *real_parent
kernel/exit.c:306:35: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected struct task_struct *task @@ got struct task_struct [noderef] __rcu *real_parent @@
kernel/exit.c:306:35: sparse: expected struct task_struct *task
kernel/exit.c:306:35: sparse: got struct task_struct [noderef] __rcu *real_parent
kernel/exit.c:351:24: sparse: sparse: incorrect type in assignment (different address spaces) @@ expected struct task_struct *parent @@ got struct task_struct [noderef] __rcu *real_parent @@
kernel/exit.c:351:24: sparse: expected struct task_struct *parent
kernel/exit.c:351:24: sparse: got struct task_struct [noderef] __rcu *real_parent
kernel/exit.c:378:27: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected struct spinlock [usertype] *lock @@ got struct spinlock [noderef] __rcu * @@
kernel/exit.c:378:27: sparse: expected struct spinlock [usertype] *lock
kernel/exit.c:378:27: sparse: got struct spinlock [noderef] __rcu *
kernel/exit.c:381:29: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected struct spinlock [usertype] *lock @@ got struct spinlock [noderef] __rcu * @@
kernel/exit.c:381:29: sparse: expected struct spinlock [usertype] *lock
kernel/exit.c:381:29: sparse: got struct spinlock [noderef] __rcu *
kernel/exit.c:604:29: sparse: sparse: incorrect type in assignment (different address spaces) @@ expected struct task_struct *reaper @@ got struct task_struct [noderef] __rcu *real_parent @@
kernel/exit.c:604:29: sparse: expected struct task_struct *reaper
kernel/exit.c:604:29: sparse: got struct task_struct [noderef] __rcu *real_parent
kernel/exit.c:606:29: sparse: sparse: incorrect type in assignment (different address spaces) @@ expected struct task_struct *reaper @@ got struct task_struct [noderef] __rcu *real_parent @@
kernel/exit.c:606:29: sparse: expected struct task_struct *reaper
kernel/exit.c:606:29: sparse: got struct task_struct [noderef] __rcu *real_parent
kernel/exit.c:930:63: sparse: sparse: incorrect type in initializer (different address spaces) @@ expected struct sighand_struct *const sighand @@ got struct sighand_struct [noderef] __rcu *sighand @@
kernel/exit.c:930:63: sparse: expected struct sighand_struct *const sighand
kernel/exit.c:930:63: sparse: got struct sighand_struct [noderef] __rcu *sighand
kernel/exit.c:1085:39: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected struct spinlock [usertype] *lock @@ got struct spinlock [noderef] __rcu * @@
kernel/exit.c:1085:39: sparse: expected struct spinlock [usertype] *lock
kernel/exit.c:1085:39: sparse: got struct spinlock [noderef] __rcu *
kernel/exit.c:1110:41: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected struct spinlock [usertype] *lock @@ got struct spinlock [noderef] __rcu * @@
kernel/exit.c:1110:41: sparse: expected struct spinlock [usertype] *lock
kernel/exit.c:1110:41: sparse: got struct spinlock [noderef] __rcu *
kernel/exit.c:1199:25: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected struct spinlock [usertype] *lock @@ got struct spinlock [noderef] __rcu * @@
kernel/exit.c:1199:25: sparse: expected struct spinlock [usertype] *lock
kernel/exit.c:1199:25: sparse: got struct spinlock [noderef] __rcu *
kernel/exit.c:1214:27: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected struct spinlock [usertype] *lock @@ got struct spinlock [noderef] __rcu * @@
kernel/exit.c:1214:27: sparse: expected struct spinlock [usertype] *lock
kernel/exit.c:1214:27: sparse: got struct spinlock [noderef] __rcu *
kernel/exit.c:1265:25: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected struct spinlock [usertype] *lock @@ got struct spinlock [noderef] __rcu * @@
kernel/exit.c:1265:25: sparse: expected struct spinlock [usertype] *lock
kernel/exit.c:1265:25: sparse: got struct spinlock [noderef] __rcu *
kernel/exit.c:1268:35: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected struct spinlock [usertype] *lock @@ got struct spinlock [noderef] __rcu * @@
kernel/exit.c:1268:35: sparse: expected struct spinlock [usertype] *lock
kernel/exit.c:1268:35: sparse: got struct spinlock [noderef] __rcu *
kernel/exit.c:1274:27: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected struct spinlock [usertype] *lock @@ got struct spinlock [noderef] __rcu * @@
kernel/exit.c:1274:27: sparse: expected struct spinlock [usertype] *lock
kernel/exit.c:1274:27: sparse: got struct spinlock [noderef] __rcu *
kernel/exit.c:1455:59: sparse: sparse: incompatible types in comparison expression (different base types):
kernel/exit.c:1455:59: sparse: void *
kernel/exit.c:1455:59: sparse: struct task_struct [noderef] __rcu *
kernel/exit.c:1471:25: sparse: sparse: incorrect type in initializer (different address spaces) @@ expected struct task_struct *parent @@ got struct task_struct [noderef] __rcu * @@
kernel/exit.c:1471:25: sparse: expected struct task_struct *parent
kernel/exit.c:1471:25: sparse: got struct task_struct [noderef] __rcu *
kernel/exit.c: note: in included file:
include/linux/ptrace.h:92:40: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected struct task_struct *p1 @@ got struct task_struct [noderef] __rcu *real_parent @@
include/linux/ptrace.h:92:40: sparse: expected struct task_struct *p1
include/linux/ptrace.h:92:40: sparse: got struct task_struct [noderef] __rcu *real_parent
include/linux/ptrace.h:92:60: sparse: sparse: incorrect type in argument 2 (different address spaces) @@ expected struct task_struct *p2 @@ got struct task_struct [noderef] __rcu *parent @@
include/linux/ptrace.h:92:60: sparse: expected struct task_struct *p2
include/linux/ptrace.h:92:60: sparse: got struct task_struct [noderef] __rcu *parent
include/linux/ptrace.h:92:40: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected struct task_struct *p1 @@ got struct task_struct [noderef] __rcu *real_parent @@
include/linux/ptrace.h:92:40: sparse: expected struct task_struct *p1
include/linux/ptrace.h:92:40: sparse: got struct task_struct [noderef] __rcu *real_parent
include/linux/ptrace.h:92:60: sparse: sparse: incorrect type in argument 2 (different address spaces) @@ expected struct task_struct *p2 @@ got struct task_struct [noderef] __rcu *parent @@
include/linux/ptrace.h:92:60: sparse: expected struct task_struct *p2
include/linux/ptrace.h:92:60: sparse: got struct task_struct [noderef] __rcu *parent
kernel/exit.c: note: in included file (through include/linux/sched/signal.h, include/linux/rcuwait.h, include/linux/percpu-rwsem.h, ...):
include/linux/sched/task.h:110:21: sparse: sparse: context imbalance in 'wait_task_zombie' - unexpected unlock
include/linux/sched/task.h:110:21: sparse: sparse: context imbalance in 'wait_task_stopped' - unexpected unlock
include/linux/sched/task.h:110:21: sparse: sparse: context imbalance in 'wait_task_continued' - unexpected unlock
kernel/exit.c: note: in included file:
include/linux/ptrace.h:92:40: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected struct task_struct *p1 @@ got struct task_struct [noderef] __rcu *real_parent @@
include/linux/ptrace.h:92:40: sparse: expected struct task_struct *p1
include/linux/ptrace.h:92:40: sparse: got struct task_struct [noderef] __rcu *real_parent
include/linux/ptrace.h:92:60: sparse: sparse: incorrect type in argument 2 (different address spaces) @@ expected struct task_struct *p2 @@ got struct task_struct [noderef] __rcu *parent @@
include/linux/ptrace.h:92:60: sparse: expected struct task_struct *p2
include/linux/ptrace.h:92:60: sparse: got struct task_struct [noderef] __rcu *parent
kernel/exit.c:1563:9: sparse: sparse: context imbalance in 'do_wait' - wrong count at exit
--
init/init_task.c:107:28: sparse: sparse: incorrect type in initializer (different address spaces) @@ expected struct task_struct [noderef] __rcu *real_parent @@ got struct task_struct * @@
init/init_task.c:107:28: sparse: expected struct task_struct [noderef] __rcu *real_parent
init/init_task.c:107:28: sparse: got struct task_struct *
init/init_task.c:108:28: sparse: sparse: incorrect type in initializer (different address spaces) @@ expected struct task_struct [noderef] __rcu *parent @@ got struct task_struct * @@
init/init_task.c:108:28: sparse: expected struct task_struct [noderef] __rcu *parent
init/init_task.c:108:28: sparse: got struct task_struct *
>> init/init_task.c:112:28: sparse: sparse: incorrect type in initializer (different address spaces) @@ expected struct task_struct [noderef] __rcu *caba @@ got struct task_struct * @@
init/init_task.c:112:28: sparse: expected struct task_struct [noderef] __rcu *caba
init/init_task.c:112:28: sparse: got struct task_struct *
init/init_task.c:125:28: sparse: sparse: incorrect type in initializer (different address spaces) @@ expected struct sighand_struct [noderef] __rcu *sighand @@ got struct sighand_struct * @@
init/init_task.c:125:28: sparse: expected struct sighand_struct [noderef] __rcu *sighand
init/init_task.c:125:28: sparse: got struct sighand_struct *

vim +2407 kernel/fork.c

2355
2356 /*
2357 * Ensure that the cgroup subsystem policies allow the new process to be
2358 * forked. It should be noted that the new process's css_set can be changed
2359 * between here and cgroup_post_fork() if an organisation operation is in
2360 * progress.
2361 */
2362 retval = cgroup_can_fork(p, args);
2363 if (retval)
2364 goto bad_fork_put_pidfd;
2365
2366 /*
2367 * Now that the cgroups are pinned, re-clone the parent cgroup and put
2368 * the new task on the correct runqueue. All this *before* the task
2369 * becomes visible.
2370 *
2371 * This isn't part of ->can_fork() because while the re-cloning is
2372 * cgroup specific, it unconditionally needs to place the task on a
2373 * runqueue.
2374 */
2375 sched_cgroup_fork(p, args);
2376
2377 /*
2378 * From this point on we must avoid any synchronous user-space
2379 * communication until we take the tasklist-lock. In particular, we do
2380 * not want user-space to be able to predict the process start-time by
2381 * stalling fork(2) after we recorded the start_time but before it is
2382 * visible to the system.
2383 */
2384
2385 p->start_time = ktime_get_ns();
2386 p->start_boottime = ktime_get_boottime_ns();
2387
2388 /*
2389 * Make it visible to the rest of the system, but dont wake it up yet.
2390 * Need tasklist lock for parent etc handling!
2391 */
2392 write_lock_irq(&tasklist_lock);
2393
2394 /* CLONE_PARENT re-uses the old parent */
2395 if (clone_flags & (CLONE_PARENT|CLONE_THREAD)) {
2396 p->real_parent = current->real_parent;
2397 p->parent_exec_id = current->parent_exec_id;
2398 if (clone_flags & CLONE_THREAD)
2399 p->exit_signal = -1;
2400 else
2401 p->exit_signal = current->group_leader->exit_signal;
2402 } else {
2403 p->real_parent = current;
2404 p->parent_exec_id = current->self_exec_id;
2405 p->exit_signal = args->exit_signal;
2406 }
> 2407 p->caba = current;
2408
2409 klp_copy_process(p);
2410
2411 sched_core_fork(p);
2412
2413 spin_lock(&current->sighand->siglock);
2414
2415 /*
2416 * Copy seccomp details explicitly here, in case they were changed
2417 * before holding sighand lock.
2418 */
2419 copy_seccomp(p);
2420
2421 rv_task_fork(p);
2422
2423 rseq_fork(p, clone_flags);
2424
2425 /* Don't start children in a dying pid namespace */
2426 if (unlikely(!(ns_of_pid(pid)->pid_allocated & PIDNS_ADDING))) {
2427 retval = -ENOMEM;
2428 goto bad_fork_cancel_cgroup;
2429 }
2430
2431 /* Let kill terminate clone/fork in the middle */
2432 if (fatal_signal_pending(current)) {
2433 retval = -EINTR;
2434 goto bad_fork_cancel_cgroup;
2435 }
2436
2437 init_task_pid_links(p);
2438 if (likely(p->pid)) {
2439 ptrace_init_task(p, (clone_flags & CLONE_PTRACE) || trace);
2440
2441 init_task_pid(p, PIDTYPE_PID, pid);
2442 if (thread_group_leader(p)) {
2443 init_task_pid(p, PIDTYPE_TGID, pid);
2444 init_task_pid(p, PIDTYPE_PGID, task_pgrp(current));
2445 init_task_pid(p, PIDTYPE_SID, task_session(current));
2446
2447 if (is_child_reaper(pid)) {
2448 ns_of_pid(pid)->child_reaper = p;
2449 p->signal->flags |= SIGNAL_UNKILLABLE;
2450 }
2451 p->signal->shared_pending.signal = delayed.signal;
2452 p->signal->tty = tty_kref_get(current->signal->tty);
2453 /*
2454 * Inherit has_child_subreaper flag under the same
2455 * tasklist_lock with adding child to the process tree
2456 * for propagate_has_child_subreaper optimization.
2457 */
2458 p->signal->has_child_subreaper = p->real_parent->signal->has_child_subreaper ||
2459 p->real_parent->signal->is_child_subreaper;
2460 list_add_tail(&p->sibling, &p->real_parent->children);
2461 list_add_tail(&p->cabd, &p->caba->cabds);
2462 list_add_tail_rcu(&p->tasks, &init_task.tasks);
2463 attach_pid(p, PIDTYPE_TGID);
2464 attach_pid(p, PIDTYPE_PGID);
2465 attach_pid(p, PIDTYPE_SID);
2466 __this_cpu_inc(process_counts);
2467 } else {
2468 current->signal->nr_threads++;
2469 atomic_inc(&current->signal->live);
2470 refcount_inc(&current->signal->sigcnt);
2471 task_join_group_stop(p);
2472 list_add_tail_rcu(&p->thread_group,
2473 &p->group_leader->thread_group);
2474 list_add_tail_rcu(&p->thread_node,
2475 &p->signal->thread_head);
2476 }
2477 attach_pid(p, PIDTYPE_PID);
2478 nr_threads++;
2479 }
2480 total_forks++;
2481 hlist_del_init(&delayed.node);
2482 spin_unlock(&current->sighand->siglock);
2483 syscall_tracepoint_update(p);
2484 write_unlock_irq(&tasklist_lock);
2485
2486 if (pidfile)
2487 fd_install(pidfd, pidfile);
2488
2489 proc_fork_connector(p);
2490 sched_post_fork(p);
2491 cgroup_post_fork(p, args);
2492 perf_event_fork(p);
2493
2494 trace_task_newtask(p, clone_flags);
2495 uprobe_copy_process(p, clone_flags);
2496
2497 copy_oom_score_adj(clone_flags, p);
2498
2499 return p;
2500
2501 bad_fork_cancel_cgroup:
2502 sched_core_free(p);
2503 spin_unlock(&current->sighand->siglock);
2504 write_unlock_irq(&tasklist_lock);
2505 cgroup_cancel_fork(p, args);
2506 bad_fork_put_pidfd:
2507 if (clone_flags & CLONE_PIDFD) {
2508 fput(pidfile);
2509 put_unused_fd(pidfd);
2510 }
2511 bad_fork_free_pid:
2512 if (pid != &init_struct_pid)
2513 free_pid(pid);
2514 bad_fork_cleanup_thread:
2515 exit_thread(p);
2516 bad_fork_cleanup_io:
2517 if (p->io_context)
2518 exit_io_context(p);
2519 bad_fork_cleanup_namespaces:
2520 exit_task_namespaces(p);
2521 bad_fork_cleanup_mm:
2522 if (p->mm) {
2523 mm_clear_owner(p->mm, p);
2524 mmput(p->mm);
2525 }
2526 bad_fork_cleanup_signal:
2527 if (!(clone_flags & CLONE_THREAD))
2528 free_signal_struct(p->signal);
2529 bad_fork_cleanup_sighand:
2530 __cleanup_sighand(p->sighand);
2531 bad_fork_cleanup_fs:
2532 exit_fs(p); /* blocking */
2533 bad_fork_cleanup_files:
2534 exit_files(p); /* blocking */
2535 bad_fork_cleanup_semundo:
2536 exit_sem(p);
2537 bad_fork_cleanup_security:
2538 security_task_free(p);
2539 bad_fork_cleanup_audit:
2540 audit_free(p);
2541 bad_fork_cleanup_perf:
2542 perf_event_free_task(p);
2543 bad_fork_cleanup_policy:
2544 lockdep_free_task(p);
2545 #ifdef CONFIG_NUMA
2546 mpol_put(p->mempolicy);
2547 #endif
2548 bad_fork_cleanup_delayacct:
2549 delayacct_tsk_free(p);
2550 bad_fork_cleanup_count:
2551 dec_rlimit_ucounts(task_ucounts(p), UCOUNT_RLIMIT_NPROC, 1);
2552 exit_creds(p);
2553 bad_fork_free:
2554 WRITE_ONCE(p->__state, TASK_DEAD);
2555 exit_task_stack_account(p);
2556 put_task_stack(p);
2557 delayed_free_task(p);
2558 fork_out:
2559 spin_lock_irq(&current->sighand->siglock);
2560 hlist_del_init(&delayed.node);
2561 spin_unlock_irq(&current->sighand->siglock);
2562 return ERR_PTR(retval);
2563 }
2564

--
0-DAY CI Kernel Test Service
https://01.org/lkp

2022-09-08 22:20:33

by Pavel Tikhomirov

Subject: Re: [PATCH v3 1/2] Add CABA tree to task_struct

On 09.09.2022 00:29, kernel test robot wrote:
> Hi Pavel,
>
> Thank you for the patch! Perhaps something to improve:
>
> [auto build test WARNING on shuah-kselftest/next]
> [also build test WARNING on kees/for-next/execve tip/sched/core linus/master v6.0-rc4 next-20220908]
> [If your patch is applied to the wrong git tree, kindly drop us a note.
> And when submitting patch, we suggest to use '--base' as documented in
> https://git-scm.com/docs/git-format-patch#_base_tree_information]
>
> url: https://github.com/intel-lab-lkp/linux/commits/Pavel-Tikhomirov/Introduce-CABA-helper-process-tree/20220908-220639
> base: https://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest.git next
> config: s390-randconfig-s043-20220907 (https://download.01.org/0day-ci/archive/20220909/[email protected]/config)
> compiler: s390-linux-gcc (GCC) 12.1.0
> reproduce:
> wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
> chmod +x ~/bin/make.cross
> # apt-get install sparse
> # sparse version: v0.6.4-39-gce1a6720-dirty
> # https://github.com/intel-lab-lkp/linux/commit/17a897a33137d4f49f99c8be8d619f6f711fccdb
> git remote add linux-review https://github.com/intel-lab-lkp/linux
> git fetch --no-tags linux-review Pavel-Tikhomirov/Introduce-CABA-helper-process-tree/20220908-220639
> git checkout 17a897a33137d4f49f99c8be8d619f6f711fccdb
> # save the config file
> mkdir build_dir && cp config build_dir/.config
> COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__' O=build_dir ARCH=s390 SHELL=/bin/bash
>
> If you fix the issue, kindly add following tag where applicable
> Reported-by: kernel test robot <[email protected]>
>
> sparse warnings: (new ones prefixed by >>)
> kernel/fork.c:1307:22: sparse: sparse: incorrect type in assignment (different address spaces) @@ expected struct file *[assigned] old_exe_file @@ got struct file [noderef] __rcu *[assigned] __ret @@
> kernel/fork.c:1307:22: sparse: expected struct file *[assigned] old_exe_file
> kernel/fork.c:1307:22: sparse: got struct file [noderef] __rcu *[assigned] __ret
> kernel/fork.c:1638:38: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected struct refcount_struct [usertype] *r @@ got struct refcount_struct [noderef] __rcu * @@
> kernel/fork.c:1638:38: sparse: expected struct refcount_struct [usertype] *r
> kernel/fork.c:1638:38: sparse: got struct refcount_struct [noderef] __rcu *
> kernel/fork.c:1647:31: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected struct spinlock [usertype] *lock @@ got struct spinlock [noderef] __rcu * @@
> kernel/fork.c:1647:31: sparse: expected struct spinlock [usertype] *lock
> kernel/fork.c:1647:31: sparse: got struct spinlock [noderef] __rcu *
> kernel/fork.c:1648:9: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected void const * @@ got struct k_sigaction [noderef] __rcu * @@
> kernel/fork.c:1648:9: sparse: expected void const *
> kernel/fork.c:1648:9: sparse: got struct k_sigaction [noderef] __rcu *
> kernel/fork.c:1648:9: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected void const * @@ got struct k_sigaction [noderef] __rcu * @@
> kernel/fork.c:1648:9: sparse: expected void const *
> kernel/fork.c:1648:9: sparse: got struct k_sigaction [noderef] __rcu *
> kernel/fork.c:1648:9: sparse: sparse: incorrect type in argument 2 (different address spaces) @@ expected void const * @@ got struct k_sigaction [noderef] __rcu * @@
> kernel/fork.c:1648:9: sparse: expected void const *
> kernel/fork.c:1648:9: sparse: got struct k_sigaction [noderef] __rcu *
> kernel/fork.c:1649:33: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected struct spinlock [usertype] *lock @@ got struct spinlock [noderef] __rcu * @@
> kernel/fork.c:1649:33: sparse: expected struct spinlock [usertype] *lock
> kernel/fork.c:1649:33: sparse: got struct spinlock [noderef] __rcu *
> kernel/fork.c:1742:9: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected struct arch_spinlock_t [usertype] *lp @@ got struct arch_spinlock_t [noderef] __rcu * @@
> kernel/fork.c:1742:9: sparse: expected struct arch_spinlock_t [usertype] *lp
> kernel/fork.c:1742:9: sparse: got struct arch_spinlock_t [noderef] __rcu *
> kernel/fork.c:2077:31: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected struct spinlock [usertype] *lock @@ got struct spinlock [noderef] __rcu * @@
> kernel/fork.c:2077:31: sparse: expected struct spinlock [usertype] *lock
> kernel/fork.c:2077:31: sparse: got struct spinlock [noderef] __rcu *
> kernel/fork.c:2081:33: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected struct spinlock [usertype] *lock @@ got struct spinlock [noderef] __rcu * @@
> kernel/fork.c:2081:33: sparse: expected struct spinlock [usertype] *lock
> kernel/fork.c:2081:33: sparse: got struct spinlock [noderef] __rcu *
> kernel/fork.c:2403:32: sparse: sparse: incorrect type in assignment (different address spaces) @@ expected struct task_struct [noderef] __rcu *real_parent @@ got struct task_struct * @@
> kernel/fork.c:2403:32: sparse: expected struct task_struct [noderef] __rcu *real_parent
> kernel/fork.c:2403:32: sparse: got struct task_struct *
>>> kernel/fork.c:2407:17: sparse: sparse: incorrect type in assignment (different address spaces) @@ expected struct task_struct [noderef] __rcu *caba @@ got struct task_struct * @@
> kernel/fork.c:2407:17: sparse: expected struct task_struct [noderef] __rcu *caba
> kernel/fork.c:2407:17: sparse: got struct task_struct *
> kernel/fork.c:2413:27: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected struct spinlock [usertype] *lock @@ got struct spinlock [noderef] __rcu * @@
> kernel/fork.c:2413:27: sparse: expected struct spinlock [usertype] *lock
> kernel/fork.c:2413:27: sparse: got struct spinlock [noderef] __rcu *
> kernel/fork.c:2460:54: sparse: sparse: incorrect type in argument 2 (different address spaces) @@ expected struct list_head *head @@ got struct list_head [noderef] __rcu * @@
> kernel/fork.c:2460:54: sparse: expected struct list_head *head
> kernel/fork.c:2460:54: sparse: got struct list_head [noderef] __rcu *
> kernel/fork.c:2461:51: sparse: sparse: incorrect type in argument 2 (different address spaces) @@ expected struct list_head *head @@ got struct list_head [noderef] __rcu * @@
> kernel/fork.c:2461:51: sparse: expected struct list_head *head
> kernel/fork.c:2461:51: sparse: got struct list_head [noderef] __rcu *
> kernel/fork.c:2482:29: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected struct spinlock [usertype] *lock @@ got struct spinlock [noderef] __rcu * @@
> kernel/fork.c:2482:29: sparse: expected struct spinlock [usertype] *lock
> kernel/fork.c:2482:29: sparse: got struct spinlock [noderef] __rcu *
> kernel/fork.c:2503:29: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected struct spinlock [usertype] *lock @@ got struct spinlock [noderef] __rcu * @@
> kernel/fork.c:2503:29: sparse: expected struct spinlock [usertype] *lock
> kernel/fork.c:2503:29: sparse: got struct spinlock [noderef] __rcu *
> kernel/fork.c:2530:28: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected struct sighand_struct *sighand @@ got struct sighand_struct [noderef] __rcu *sighand @@
> kernel/fork.c:2530:28: sparse: expected struct sighand_struct *sighand
> kernel/fork.c:2530:28: sparse: got struct sighand_struct [noderef] __rcu *sighand
> kernel/fork.c:2559:31: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected struct spinlock [usertype] *lock @@ got struct spinlock [noderef] __rcu * @@
> kernel/fork.c:2559:31: sparse: expected struct spinlock [usertype] *lock
> kernel/fork.c:2559:31: sparse: got struct spinlock [noderef] __rcu *
> kernel/fork.c:2561:33: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected struct spinlock [usertype] *lock @@ got struct spinlock [noderef] __rcu * @@
> kernel/fork.c:2561:33: sparse: expected struct spinlock [usertype] *lock
> kernel/fork.c:2561:33: sparse: got struct spinlock [noderef] __rcu *
> kernel/fork.c:2997:24: sparse: sparse: incorrect type in assignment (different address spaces) @@ expected struct task_struct *[assigned] parent @@ got struct task_struct [noderef] __rcu *real_parent @@
> kernel/fork.c:2997:24: sparse: expected struct task_struct *[assigned] parent
> kernel/fork.c:2997:24: sparse: got struct task_struct [noderef] __rcu *real_parent
> kernel/fork.c:3078:43: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected struct refcount_struct const [usertype] *r @@ got struct refcount_struct [noderef] __rcu * @@
> kernel/fork.c:3078:43: sparse: expected struct refcount_struct const [usertype] *r
> kernel/fork.c:3078:43: sparse: got struct refcount_struct [noderef] __rcu *
> kernel/fork.c:2122:22: sparse: sparse: dereference of noderef expression
> kernel/fork.c: note: in included file (through arch/s390/include/asm/stacktrace.h, arch/s390/include/asm/perf_event.h, include/linux/perf_event.h, ...):
> include/linux/ptrace.h:210:45: sparse: sparse: incorrect type in argument 2 (different address spaces) @@ expected struct task_struct *new_parent @@ got struct task_struct [noderef] __rcu *parent @@
> include/linux/ptrace.h:210:45: sparse: expected struct task_struct *new_parent
> include/linux/ptrace.h:210:45: sparse: got struct task_struct [noderef] __rcu *parent
> include/linux/ptrace.h:210:62: sparse: sparse: incorrect type in argument 3 (different address spaces) @@ expected struct cred const *ptracer_cred @@ got struct cred const [noderef] __rcu *ptracer_cred @@
> include/linux/ptrace.h:210:62: sparse: expected struct cred const *ptracer_cred
> include/linux/ptrace.h:210:62: sparse: got struct cred const [noderef] __rcu *ptracer_cred
> kernel/fork.c:2458:59: sparse: sparse: dereference of noderef expression
> kernel/fork.c:2459:59: sparse: sparse: dereference of noderef expression
> --
>>> kernel/exit.c:84:26: sparse: sparse: incorrect type in assignment (different address spaces) @@ expected struct task_struct *[assigned] new_caba @@ got struct task_struct [noderef] __rcu *caba @@
> kernel/exit.c:84:26: sparse: expected struct task_struct *[assigned] new_caba
> kernel/exit.c:84:26: sparse: got struct task_struct [noderef] __rcu *caba
> kernel/exit.c:302:37: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected struct task_struct *tsk @@ got struct task_struct [noderef] __rcu *real_parent @@
> kernel/exit.c:302:37: sparse: expected struct task_struct *tsk
> kernel/exit.c:302:37: sparse: got struct task_struct [noderef] __rcu *real_parent
> kernel/exit.c:305:32: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected struct task_struct *task @@ got struct task_struct [noderef] __rcu *real_parent @@
> kernel/exit.c:305:32: sparse: expected struct task_struct *task
> kernel/exit.c:305:32: sparse: got struct task_struct [noderef] __rcu *real_parent
> kernel/exit.c:306:35: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected struct task_struct *task @@ got struct task_struct [noderef] __rcu *real_parent @@
> kernel/exit.c:306:35: sparse: expected struct task_struct *task
> kernel/exit.c:306:35: sparse: got struct task_struct [noderef] __rcu *real_parent
> kernel/exit.c:351:24: sparse: sparse: incorrect type in assignment (different address spaces) @@ expected struct task_struct *parent @@ got struct task_struct [noderef] __rcu *real_parent @@
> kernel/exit.c:351:24: sparse: expected struct task_struct *parent
> kernel/exit.c:351:24: sparse: got struct task_struct [noderef] __rcu *real_parent
> kernel/exit.c:378:27: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected struct spinlock [usertype] *lock @@ got struct spinlock [noderef] __rcu * @@
> kernel/exit.c:378:27: sparse: expected struct spinlock [usertype] *lock
> kernel/exit.c:378:27: sparse: got struct spinlock [noderef] __rcu *
> kernel/exit.c:381:29: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected struct spinlock [usertype] *lock @@ got struct spinlock [noderef] __rcu * @@
> kernel/exit.c:381:29: sparse: expected struct spinlock [usertype] *lock
> kernel/exit.c:381:29: sparse: got struct spinlock [noderef] __rcu *
> kernel/exit.c:604:29: sparse: sparse: incorrect type in assignment (different address spaces) @@ expected struct task_struct *reaper @@ got struct task_struct [noderef] __rcu *real_parent @@
> kernel/exit.c:604:29: sparse: expected struct task_struct *reaper
> kernel/exit.c:604:29: sparse: got struct task_struct [noderef] __rcu *real_parent
> kernel/exit.c:606:29: sparse: sparse: incorrect type in assignment (different address spaces) @@ expected struct task_struct *reaper @@ got struct task_struct [noderef] __rcu *real_parent @@
> kernel/exit.c:606:29: sparse: expected struct task_struct *reaper
> kernel/exit.c:606:29: sparse: got struct task_struct [noderef] __rcu *real_parent
> kernel/exit.c:930:63: sparse: sparse: incorrect type in initializer (different address spaces) @@ expected struct sighand_struct *const sighand @@ got struct sighand_struct [noderef] __rcu *sighand @@
> kernel/exit.c:930:63: sparse: expected struct sighand_struct *const sighand
> kernel/exit.c:930:63: sparse: got struct sighand_struct [noderef] __rcu *sighand
> kernel/exit.c:1085:39: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected struct spinlock [usertype] *lock @@ got struct spinlock [noderef] __rcu * @@
> kernel/exit.c:1085:39: sparse: expected struct spinlock [usertype] *lock
> kernel/exit.c:1085:39: sparse: got struct spinlock [noderef] __rcu *
> kernel/exit.c:1110:41: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected struct spinlock [usertype] *lock @@ got struct spinlock [noderef] __rcu * @@
> kernel/exit.c:1110:41: sparse: expected struct spinlock [usertype] *lock
> kernel/exit.c:1110:41: sparse: got struct spinlock [noderef] __rcu *
> kernel/exit.c:1199:25: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected struct spinlock [usertype] *lock @@ got struct spinlock [noderef] __rcu * @@
> kernel/exit.c:1199:25: sparse: expected struct spinlock [usertype] *lock
> kernel/exit.c:1199:25: sparse: got struct spinlock [noderef] __rcu *
> kernel/exit.c:1214:27: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected struct spinlock [usertype] *lock @@ got struct spinlock [noderef] __rcu * @@
> kernel/exit.c:1214:27: sparse: expected struct spinlock [usertype] *lock
> kernel/exit.c:1214:27: sparse: got struct spinlock [noderef] __rcu *
> kernel/exit.c:1265:25: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected struct spinlock [usertype] *lock @@ got struct spinlock [noderef] __rcu * @@
> kernel/exit.c:1265:25: sparse: expected struct spinlock [usertype] *lock
> kernel/exit.c:1265:25: sparse: got struct spinlock [noderef] __rcu *
> kernel/exit.c:1268:35: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected struct spinlock [usertype] *lock @@ got struct spinlock [noderef] __rcu * @@
> kernel/exit.c:1268:35: sparse: expected struct spinlock [usertype] *lock
> kernel/exit.c:1268:35: sparse: got struct spinlock [noderef] __rcu *
> kernel/exit.c:1274:27: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected struct spinlock [usertype] *lock @@ got struct spinlock [noderef] __rcu * @@
> kernel/exit.c:1274:27: sparse: expected struct spinlock [usertype] *lock
> kernel/exit.c:1274:27: sparse: got struct spinlock [noderef] __rcu *
> kernel/exit.c:1455:59: sparse: sparse: incompatible types in comparison expression (different base types):
> kernel/exit.c:1455:59: sparse: void *
> kernel/exit.c:1455:59: sparse: struct task_struct [noderef] __rcu *
> kernel/exit.c:1471:25: sparse: sparse: incorrect type in initializer (different address spaces) @@ expected struct task_struct *parent @@ got struct task_struct [noderef] __rcu * @@
> kernel/exit.c:1471:25: sparse: expected struct task_struct *parent
> kernel/exit.c:1471:25: sparse: got struct task_struct [noderef] __rcu *
> kernel/exit.c: note: in included file:
> include/linux/ptrace.h:92:40: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected struct task_struct *p1 @@ got struct task_struct [noderef] __rcu *real_parent @@
> include/linux/ptrace.h:92:40: sparse: expected struct task_struct *p1
> include/linux/ptrace.h:92:40: sparse: got struct task_struct [noderef] __rcu *real_parent
> include/linux/ptrace.h:92:60: sparse: sparse: incorrect type in argument 2 (different address spaces) @@ expected struct task_struct *p2 @@ got struct task_struct [noderef] __rcu *parent @@
> include/linux/ptrace.h:92:60: sparse: expected struct task_struct *p2
> include/linux/ptrace.h:92:60: sparse: got struct task_struct [noderef] __rcu *parent
> include/linux/ptrace.h:92:40: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected struct task_struct *p1 @@ got struct task_struct [noderef] __rcu *real_parent @@
> include/linux/ptrace.h:92:40: sparse: expected struct task_struct *p1
> include/linux/ptrace.h:92:40: sparse: got struct task_struct [noderef] __rcu *real_parent
> include/linux/ptrace.h:92:60: sparse: sparse: incorrect type in argument 2 (different address spaces) @@ expected struct task_struct *p2 @@ got struct task_struct [noderef] __rcu *parent @@
> include/linux/ptrace.h:92:60: sparse: expected struct task_struct *p2
> include/linux/ptrace.h:92:60: sparse: got struct task_struct [noderef] __rcu *parent
> kernel/exit.c: note: in included file (through include/linux/sched/signal.h, include/linux/rcuwait.h, include/linux/percpu-rwsem.h, ...):
> include/linux/sched/task.h:110:21: sparse: sparse: context imbalance in 'wait_task_zombie' - unexpected unlock
> include/linux/sched/task.h:110:21: sparse: sparse: context imbalance in 'wait_task_stopped' - unexpected unlock
> include/linux/sched/task.h:110:21: sparse: sparse: context imbalance in 'wait_task_continued' - unexpected unlock
> kernel/exit.c: note: in included file:
> include/linux/ptrace.h:92:40: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected struct task_struct *p1 @@ got struct task_struct [noderef] __rcu *real_parent @@
> include/linux/ptrace.h:92:40: sparse: expected struct task_struct *p1
> include/linux/ptrace.h:92:40: sparse: got struct task_struct [noderef] __rcu *real_parent
> include/linux/ptrace.h:92:60: sparse: sparse: incorrect type in argument 2 (different address spaces) @@ expected struct task_struct *p2 @@ got struct task_struct [noderef] __rcu *parent @@
> include/linux/ptrace.h:92:60: sparse: expected struct task_struct *p2
> include/linux/ptrace.h:92:60: sparse: got struct task_struct [noderef] __rcu *parent
> kernel/exit.c:1563:9: sparse: sparse: context imbalance in 'do_wait' - wrong count at exit
> --
> init/init_task.c:107:28: sparse: sparse: incorrect type in initializer (different address spaces) @@ expected struct task_struct [noderef] __rcu *real_parent @@ got struct task_struct * @@
> init/init_task.c:107:28: sparse: expected struct task_struct [noderef] __rcu *real_parent
> init/init_task.c:107:28: sparse: got struct task_struct *
> init/init_task.c:108:28: sparse: sparse: incorrect type in initializer (different address spaces) @@ expected struct task_struct [noderef] __rcu *parent @@ got struct task_struct * @@
> init/init_task.c:108:28: sparse: expected struct task_struct [noderef] __rcu *parent
> init/init_task.c:108:28: sparse: got struct task_struct *
>>> init/init_task.c:112:28: sparse: sparse: incorrect type in initializer (different address spaces) @@ expected struct task_struct [noderef] __rcu *caba @@ got struct task_struct * @@
> init/init_task.c:112:28: sparse: expected struct task_struct [noderef] __rcu *caba
> init/init_task.c:112:28: sparse: got struct task_struct *
> init/init_task.c:125:28: sparse: sparse: incorrect type in initializer (different address spaces) @@ expected struct sighand_struct [noderef] __rcu *sighand @@ got struct sighand_struct * @@
> init/init_task.c:125:28: sparse: expected struct sighand_struct [noderef] __rcu *sighand
> init/init_task.c:125:28: sparse: got struct sighand_struct *
>
> vim +2407 kernel/fork.c
>
> 2355
> 2356 /*
> 2357 * Ensure that the cgroup subsystem policies allow the new process to be
> 2358 * forked. It should be noted that the new process's css_set can be changed
> 2359 * between here and cgroup_post_fork() if an organisation operation is in
> 2360 * progress.
> 2361 */
> 2362 retval = cgroup_can_fork(p, args);
> 2363 if (retval)
> 2364 goto bad_fork_put_pidfd;
> 2365
> 2366 /*
> 2367 * Now that the cgroups are pinned, re-clone the parent cgroup and put
> 2368 * the new task on the correct runqueue. All this *before* the task
> 2369 * becomes visible.
> 2370 *
> 2371 * This isn't part of ->can_fork() because while the re-cloning is
> 2372 * cgroup specific, it unconditionally needs to place the task on a
> 2373 * runqueue.
> 2374 */
> 2375 sched_cgroup_fork(p, args);
> 2376
> 2377 /*
> 2378 * From this point on we must avoid any synchronous user-space
> 2379 * communication until we take the tasklist-lock. In particular, we do
> 2380 * not want user-space to be able to predict the process start-time by
> 2381 * stalling fork(2) after we recorded the start_time but before it is
> 2382 * visible to the system.
> 2383 */
> 2384
> 2385 p->start_time = ktime_get_ns();
> 2386 p->start_boottime = ktime_get_boottime_ns();
> 2387
> 2388 /*
> 2389 * Make it visible to the rest of the system, but dont wake it up yet.
> 2390 * Need tasklist lock for parent etc handling!
> 2391 */
> 2392 write_lock_irq(&tasklist_lock);
> 2393
> 2394 /* CLONE_PARENT re-uses the old parent */
> 2395 if (clone_flags & (CLONE_PARENT|CLONE_THREAD)) {
> 2396 p->real_parent = current->real_parent;
> 2397 p->parent_exec_id = current->parent_exec_id;
> 2398 if (clone_flags & CLONE_THREAD)
> 2399 p->exit_signal = -1;
> 2400 else
> 2401 p->exit_signal = current->group_leader->exit_signal;
> 2402 } else {
> 2403 p->real_parent = current;
> 2404 p->parent_exec_id = current->self_exec_id;
> 2405 p->exit_signal = args->exit_signal;
> 2406 }
>> 2407 p->caba = current;

Not sure how to fix this error, we set real_parent to current just
several lines above, but as I want to set caba to current in
CLONE_PARENT case to see actual parent after CLONE_PARENT calls, and I
can't take it from real_parent which is different in this case.

Note that I've updated this patch to v4, as for threads creation caba =
current was not a desired behaviour.

> 2408
> 2409 klp_copy_process(p);
> 2410
> 2411 sched_core_fork(p);
> 2412
> 2413 spin_lock(&current->sighand->siglock);
> 2414
> 2415 /*
> 2416 * Copy seccomp details explicitly here, in case they were changed
> 2417 * before holding sighand lock.
> 2418 */
> 2419 copy_seccomp(p);
> 2420
> 2421 rv_task_fork(p);
> 2422
> 2423 rseq_fork(p, clone_flags);
> 2424
> 2425 /* Don't start children in a dying pid namespace */
> 2426 if (unlikely(!(ns_of_pid(pid)->pid_allocated & PIDNS_ADDING))) {
> 2427 retval = -ENOMEM;
> 2428 goto bad_fork_cancel_cgroup;
> 2429 }
> 2430
> 2431 /* Let kill terminate clone/fork in the middle */
> 2432 if (fatal_signal_pending(current)) {
> 2433 retval = -EINTR;
> 2434 goto bad_fork_cancel_cgroup;
> 2435 }
> 2436
> 2437 init_task_pid_links(p);
> 2438 if (likely(p->pid)) {
> 2439 ptrace_init_task(p, (clone_flags & CLONE_PTRACE) || trace);
> 2440
> 2441 init_task_pid(p, PIDTYPE_PID, pid);
> 2442 if (thread_group_leader(p)) {
> 2443 init_task_pid(p, PIDTYPE_TGID, pid);
> 2444 init_task_pid(p, PIDTYPE_PGID, task_pgrp(current));
> 2445 init_task_pid(p, PIDTYPE_SID, task_session(current));
> 2446
> 2447 if (is_child_reaper(pid)) {
> 2448 ns_of_pid(pid)->child_reaper = p;
> 2449 p->signal->flags |= SIGNAL_UNKILLABLE;
> 2450 }
> 2451 p->signal->shared_pending.signal = delayed.signal;
> 2452 p->signal->tty = tty_kref_get(current->signal->tty);
> 2453 /*
> 2454 * Inherit has_child_subreaper flag under the same
> 2455 * tasklist_lock with adding child to the process tree
> 2456 * for propagate_has_child_subreaper optimization.
> 2457 */
> 2458 p->signal->has_child_subreaper = p->real_parent->signal->has_child_subreaper ||
> 2459 p->real_parent->signal->is_child_subreaper;
> 2460 list_add_tail(&p->sibling, &p->real_parent->children);
> 2461 list_add_tail(&p->cabd, &p->caba->cabds);
> 2462 list_add_tail_rcu(&p->tasks, &init_task.tasks);
> 2463 attach_pid(p, PIDTYPE_TGID);
> 2464 attach_pid(p, PIDTYPE_PGID);
> 2465 attach_pid(p, PIDTYPE_SID);
> 2466 __this_cpu_inc(process_counts);
> 2467 } else {
> 2468 current->signal->nr_threads++;
> 2469 atomic_inc(&current->signal->live);
> 2470 refcount_inc(&current->signal->sigcnt);
> 2471 task_join_group_stop(p);
> 2472 list_add_tail_rcu(&p->thread_group,
> 2473 &p->group_leader->thread_group);
> 2474 list_add_tail_rcu(&p->thread_node,
> 2475 &p->signal->thread_head);
> 2476 }
> 2477 attach_pid(p, PIDTYPE_PID);
> 2478 nr_threads++;
> 2479 }
> 2480 total_forks++;
> 2481 hlist_del_init(&delayed.node);
> 2482 spin_unlock(&current->sighand->siglock);
> 2483 syscall_tracepoint_update(p);
> 2484 write_unlock_irq(&tasklist_lock);
> 2485
> 2486 if (pidfile)
> 2487 fd_install(pidfd, pidfile);
> 2488
> 2489 proc_fork_connector(p);
> 2490 sched_post_fork(p);
> 2491 cgroup_post_fork(p, args);
> 2492 perf_event_fork(p);
> 2493
> 2494 trace_task_newtask(p, clone_flags);
> 2495 uprobe_copy_process(p, clone_flags);
> 2496
> 2497 copy_oom_score_adj(clone_flags, p);
> 2498
> 2499 return p;
> 2500
> 2501 bad_fork_cancel_cgroup:
> 2502 sched_core_free(p);
> 2503 spin_unlock(&current->sighand->siglock);
> 2504 write_unlock_irq(&tasklist_lock);
> 2505 cgroup_cancel_fork(p, args);
> 2506 bad_fork_put_pidfd:
> 2507 if (clone_flags & CLONE_PIDFD) {
> 2508 fput(pidfile);
> 2509 put_unused_fd(pidfd);
> 2510 }
> 2511 bad_fork_free_pid:
> 2512 if (pid != &init_struct_pid)
> 2513 free_pid(pid);
> 2514 bad_fork_cleanup_thread:
> 2515 exit_thread(p);
> 2516 bad_fork_cleanup_io:
> 2517 if (p->io_context)
> 2518 exit_io_context(p);
> 2519 bad_fork_cleanup_namespaces:
> 2520 exit_task_namespaces(p);
> 2521 bad_fork_cleanup_mm:
> 2522 if (p->mm) {
> 2523 mm_clear_owner(p->mm, p);
> 2524 mmput(p->mm);
> 2525 }
> 2526 bad_fork_cleanup_signal:
> 2527 if (!(clone_flags & CLONE_THREAD))
> 2528 free_signal_struct(p->signal);
> 2529 bad_fork_cleanup_sighand:
> 2530 __cleanup_sighand(p->sighand);
> 2531 bad_fork_cleanup_fs:
> 2532 exit_fs(p); /* blocking */
> 2533 bad_fork_cleanup_files:
> 2534 exit_files(p); /* blocking */
> 2535 bad_fork_cleanup_semundo:
> 2536 exit_sem(p);
> 2537 bad_fork_cleanup_security:
> 2538 security_task_free(p);
> 2539 bad_fork_cleanup_audit:
> 2540 audit_free(p);
> 2541 bad_fork_cleanup_perf:
> 2542 perf_event_free_task(p);
> 2543 bad_fork_cleanup_policy:
> 2544 lockdep_free_task(p);
> 2545 #ifdef CONFIG_NUMA
> 2546 mpol_put(p->mempolicy);
> 2547 #endif
> 2548 bad_fork_cleanup_delayacct:
> 2549 delayacct_tsk_free(p);
> 2550 bad_fork_cleanup_count:
> 2551 dec_rlimit_ucounts(task_ucounts(p), UCOUNT_RLIMIT_NPROC, 1);
> 2552 exit_creds(p);
> 2553 bad_fork_free:
> 2554 WRITE_ONCE(p->__state, TASK_DEAD);
> 2555 exit_task_stack_account(p);
> 2556 put_task_stack(p);
> 2557 delayed_free_task(p);
> 2558 fork_out:
> 2559 spin_lock_irq(&current->sighand->siglock);
> 2560 hlist_del_init(&delayed.node);
> 2561 spin_unlock_irq(&current->sighand->siglock);
> 2562 return ERR_PTR(retval);
> 2563 }
> 2564
>

--
Best regards, Tikhomirov Pavel
Software Developer, Virtuozzo.

2022-09-08 22:54:14

by Pavel Tikhomirov

Subject: [PATCH v4 1/2] Add CABA tree to task_struct

In linux after parent (father) process dies, children processes are
moved (reparented) to a reaper process. Roughly speaking:

1) If father has other yet alive thread, this thread would be a reaper.

2) Else if there is father's ancestor (with no pidns level change in the
middle), which has PR_SET_CHILD_SUBREAPER set, this ancestor would be a
reaper.

3) Else father's pidns init would be a reaper for fathers children.

The problem with this for CRIU is that when CRIU comes to dump processes
it does not know the order in which processes and their resources were
created. And processes can have resources which a) can only be inherited
when we clone processes, b) can only be created by specific processes
and c) are shared between several processes (the example of such a
resource is process session). For such resources CRIU restore would need
to re-invent such order of process creation which at the same time
creates the desired process tree topology and allows to inherit all
resources right.

When process reparenting involves child-sub-reapers one can drastically
mix processes in process tree so that it is not obvious how to restore
everything right.

So this is what we came up with to help CRIU to overcome this problem:

CABA = Closest Alive Born Ancestor
CABD = Closest Alive Born Descendant

We want to put processes in one more tree - CABA tree. This tree is not
affecting reparenting or process creation in any way except for
providing a new information to CRIU so that we can understand from where
the reparented child had reparented, though original father is already
dead and probably a fathers father too, we can still have information
about the process which is still alive and was originally a parent of
process sequence (of already dead processes) which lead to us - CABA.

CC: Eric Biederman <[email protected]>
CC: Kees Cook <[email protected]>
CC: Alexander Viro <[email protected]>
CC: Ingo Molnar <[email protected]>
CC: Peter Zijlstra <[email protected]>
CC: Juri Lelli <[email protected]>
CC: Vincent Guittot <[email protected]>
CC: Dietmar Eggemann <[email protected]>
CC: Steven Rostedt <[email protected]>
CC: Ben Segall <[email protected]>
CC: Mel Gorman <[email protected]>
CC: Daniel Bristot de Oliveira <[email protected]>
CC: Valentin Schneider <[email protected]>
CC: Andrew Morton <[email protected]>
CC: [email protected]
CC: [email protected]
CC: [email protected]
CC: [email protected]
CC: [email protected]
CC: Alexander Mikhalitsyn <[email protected]>

Signed-off-by: Pavel Tikhomirov <[email protected]>

--
v2: fix unused variables reported-by: kernel test robot <[email protected]>
v3: - on fork set caba to current, so that caba is always a process
which had initiated our creation, even for CLONE_PARENT case
- move caba update to a later stage (to __unhash_process), so that
zombies can be somebodies caba until fully released
v4: fix accidentally setting caba to thread leader when creating threads
---
arch/ia64/kernel/mca.c | 3 +++
fs/exec.c | 1 +
fs/proc/array.c | 20 ++++++++++++++++++++
include/linux/sched.h | 7 +++++++
init/init_task.c | 3 +++
kernel/exit.c | 21 +++++++++++++++++++++
kernel/fork.c | 11 +++++++++--
7 files changed, 64 insertions(+), 2 deletions(-)

diff --git a/arch/ia64/kernel/mca.c b/arch/ia64/kernel/mca.c
index c62a66710ad6..5e561994cff7 100644
--- a/arch/ia64/kernel/mca.c
+++ b/arch/ia64/kernel/mca.c
@@ -1793,6 +1793,9 @@ format_mca_init_stack(void *mca_data, unsigned long offset,
p->parent = p->real_parent = p->group_leader = p;
INIT_LIST_HEAD(&p->children);
INIT_LIST_HEAD(&p->sibling);
+ p->caba = p;
+ INIT_LIST_HEAD(&p->cabds);
+ INIT_LIST_HEAD(&p->cabd);
strncpy(p->comm, type, sizeof(p->comm)-1);
}

diff --git a/fs/exec.c b/fs/exec.c
index 9a5ca7b82bfc..8caaa03739ab 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -1139,6 +1139,7 @@ static int de_thread(struct task_struct *tsk)

list_replace_rcu(&leader->tasks, &tsk->tasks);
list_replace_init(&leader->sibling, &tsk->sibling);
+ list_replace_init(&leader->cabd, &tsk->cabd);

tsk->group_leader = tsk;
leader->group_leader = tsk;
diff --git a/fs/proc/array.c b/fs/proc/array.c
index 99fcbfda8e25..5fd70aebd52d 100644
--- a/fs/proc/array.c
+++ b/fs/proc/array.c
@@ -154,11 +154,28 @@ static inline void task_state(struct seq_file *m, struct pid_namespace *ns,
const struct cred *cred;
pid_t ppid, tpid = 0, tgid, ngid;
unsigned int max_fds = 0;
+#ifdef CONFIG_PID_NS
+ struct task_struct *caba;
+ struct pid *caba_pid;
+ int caba_level = 0;
+ pid_t caba_pids[MAX_PID_NS_LEVEL] = {};
+#endif

rcu_read_lock();
ppid = pid_alive(p) ?
task_tgid_nr_ns(rcu_dereference(p->real_parent), ns) : 0;

+#ifdef CONFIG_PID_NS
+ caba = rcu_dereference(p->caba);
+ caba_pid = get_task_pid(caba, PIDTYPE_PID);
+ if (caba_pid) {
+ caba_level = caba_pid->level;
+ for (g = ns->level; g <= caba_level; g++)
+ caba_pids[g] = task_pid_nr_ns(caba, caba_pid->numbers[g].ns);
+ put_pid(caba_pid);
+ }
+#endif
+
tracer = ptrace_parent(p);
if (tracer)
tpid = task_pid_nr_ns(tracer, ns);
@@ -217,6 +234,9 @@ static inline void task_state(struct seq_file *m, struct pid_namespace *ns,
seq_puts(m, "\nNSsid:");
for (g = ns->level; g <= pid->level; g++)
seq_put_decimal_ull(m, "\t", task_session_nr_ns(p, pid->numbers[g].ns));
+ seq_puts(m, "\nNScaba:");
+ for (g = ns->level; g <= caba_level; g++)
+ seq_put_decimal_ull(m, "\t", caba_pids[g]);
#endif
seq_putc(m, '\n');
}
diff --git a/include/linux/sched.h b/include/linux/sched.h
index e7b2f8a5c711..b30a2ccf1180 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -975,6 +975,13 @@ struct task_struct {
struct list_head sibling;
struct task_struct *group_leader;

+ /* Closest Alive Born Ancestor process: */
+ struct task_struct __rcu *caba;
+
+ /* Closest Alive Born Descendants list: */
+ struct list_head cabds;
+ struct list_head cabd;
+
/*
* 'ptraced' is the list of tasks this task is using ptrace() on.
*
diff --git a/init/init_task.c b/init/init_task.c
index ff6c4b9bfe6b..439da3b04dde 100644
--- a/init/init_task.c
+++ b/init/init_task.c
@@ -109,6 +109,9 @@ struct task_struct init_task
.children = LIST_HEAD_INIT(init_task.children),
.sibling = LIST_HEAD_INIT(init_task.sibling),
.group_leader = &init_task,
+ .caba = &init_task,
+ .cabds = LIST_HEAD_INIT(init_task.cabds),
+ .cabd = LIST_HEAD_INIT(init_task.cabd),
RCU_POINTER_INITIALIZER(real_cred, &init_cred),
RCU_POINTER_INITIALIZER(cred, &init_cred),
.comm = INIT_TASK_COMM,
diff --git a/kernel/exit.c b/kernel/exit.c
index 84021b24f79e..32e4a380861d 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -71,9 +71,29 @@
#include <asm/unistd.h>
#include <asm/mmu_context.h>

+static void forget_caba(struct task_struct *caba)
+{
+ struct task_struct *p, *t, *new_caba;
+
+ if (list_empty(&caba->cabds))
+ return;
+
+ if (!thread_group_leader(caba))
+ new_caba = caba->group_leader;
+ else
+ new_caba = caba->caba;
+
+ list_for_each_entry(p, &caba->cabds, cabd) {
+ for_each_thread(p, t)
+ RCU_INIT_POINTER(t->caba, new_caba);
+ }
+ list_splice_tail_init(&caba->cabds, &new_caba->cabds);
+}
+
static void __unhash_process(struct task_struct *p, bool group_dead)
{
nr_threads--;
+ forget_caba(p);
detach_pid(p, PIDTYPE_PID);
if (group_dead) {
detach_pid(p, PIDTYPE_TGID);
@@ -82,6 +102,7 @@ static void __unhash_process(struct task_struct *p, bool group_dead)

list_del_rcu(&p->tasks);
list_del_init(&p->sibling);
+ list_del_init(&p->cabd);
__this_cpu_dec(process_counts);
}
list_del_rcu(&p->thread_group);
diff --git a/kernel/fork.c b/kernel/fork.c
index 90c85b17bf69..1bd3d815d77f 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -2139,6 +2139,8 @@ static __latent_entropy struct task_struct *copy_process(
p->flags |= PF_FORKNOEXEC;
INIT_LIST_HEAD(&p->children);
INIT_LIST_HEAD(&p->sibling);
+ INIT_LIST_HEAD(&p->cabds);
+ INIT_LIST_HEAD(&p->cabd);
rcu_copy_process(p);
p->vfork_done = NULL;
spin_lock_init(&p->alloc_lock);
@@ -2393,14 +2395,18 @@ static __latent_entropy struct task_struct *copy_process(
if (clone_flags & (CLONE_PARENT|CLONE_THREAD)) {
p->real_parent = current->real_parent;
p->parent_exec_id = current->parent_exec_id;
- if (clone_flags & CLONE_THREAD)
+ if (clone_flags & CLONE_THREAD) {
p->exit_signal = -1;
- else
+ p->caba = p->real_parent;
+ } else {
p->exit_signal = current->group_leader->exit_signal;
+ p->caba = current;
+ }
} else {
p->real_parent = current;
p->parent_exec_id = current->self_exec_id;
p->exit_signal = args->exit_signal;
+ p->caba = p->real_parent;
}

klp_copy_process(p);
@@ -2455,6 +2461,7 @@ static __latent_entropy struct task_struct *copy_process(
p->signal->has_child_subreaper = p->real_parent->signal->has_child_subreaper ||
p->real_parent->signal->is_child_subreaper;
list_add_tail(&p->sibling, &p->real_parent->children);
+ list_add_tail(&p->cabd, &p->caba->cabds);
list_add_tail_rcu(&p->tasks, &init_task.tasks);
attach_pid(p, PIDTYPE_TGID);
attach_pid(p, PIDTYPE_PGID);
--
2.37.1

2022-09-09 00:01:37

by kernel test robot

Subject: Re: [PATCH v3 1/2] Add CABA tree to task_struct

Hi Pavel,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on shuah-kselftest/next]
[also build test WARNING on kees/for-next/execve tip/sched/core linus/master v6.0-rc4 next-20220908]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url: https://github.com/intel-lab-lkp/linux/commits/Pavel-Tikhomirov/Introduce-CABA-helper-process-tree/20220908-220639
base: https://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest.git next
config: loongarch-randconfig-s031-20220907 (https://download.01.org/0day-ci/archive/20220909/[email protected]/config)
compiler: loongarch64-linux-gcc (GCC) 12.1.0
reproduce:
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# apt-get install sparse
# sparse version: v0.6.4-39-gce1a6720-dirty
# https://github.com/intel-lab-lkp/linux/commit/17a897a33137d4f49f99c8be8d619f6f711fccdb
git remote add linux-review https://github.com/intel-lab-lkp/linux
git fetch --no-tags linux-review Pavel-Tikhomirov/Introduce-CABA-helper-process-tree/20220908-220639
git checkout 17a897a33137d4f49f99c8be8d619f6f711fccdb
# save the config file
mkdir build_dir && cp config build_dir/.config
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__' O=build_dir ARCH=loongarch SHELL=/bin/bash

If you fix the issue, kindly add following tag where applicable
Reported-by: kernel test robot <[email protected]>

sparse warnings: (new ones prefixed by >>)
kernel/fork.c:1098:19: sparse: sparse: incorrect type in assignment (different address spaces) @@ expected struct task_struct [noderef] __rcu *owner @@ got struct task_struct *p @@
kernel/fork.c:1098:19: sparse: expected struct task_struct [noderef] __rcu *owner
kernel/fork.c:1098:19: sparse: got struct task_struct *p
kernel/fork.c:1307:22: sparse: sparse: incorrect type in assignment (different address spaces) @@ expected struct file *[assigned] old_exe_file @@ got struct file [noderef] __rcu *[assigned] __res @@
kernel/fork.c:1307:22: sparse: expected struct file *[assigned] old_exe_file
kernel/fork.c:1307:22: sparse: got struct file [noderef] __rcu *[assigned] __res
kernel/fork.c:1638:38: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected struct refcount_struct [usertype] *r @@ got struct refcount_struct [noderef] __rcu * @@
kernel/fork.c:1638:38: sparse: expected struct refcount_struct [usertype] *r
kernel/fork.c:1638:38: sparse: got struct refcount_struct [noderef] __rcu *
kernel/fork.c:1647:31: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected struct spinlock [usertype] *lock @@ got struct spinlock [noderef] __rcu * @@
kernel/fork.c:1647:31: sparse: expected struct spinlock [usertype] *lock
kernel/fork.c:1647:31: sparse: got struct spinlock [noderef] __rcu *
kernel/fork.c:1648:36: sparse: sparse: incorrect type in argument 2 (different address spaces) @@ expected void const * @@ got struct k_sigaction [noderef] __rcu * @@
kernel/fork.c:1648:36: sparse: expected void const *
kernel/fork.c:1648:36: sparse: got struct k_sigaction [noderef] __rcu *
kernel/fork.c:1649:33: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected struct spinlock [usertype] *lock @@ got struct spinlock [noderef] __rcu * @@
kernel/fork.c:1649:33: sparse: expected struct spinlock [usertype] *lock
kernel/fork.c:1649:33: sparse: got struct spinlock [noderef] __rcu *
kernel/fork.c:2077:31: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected struct spinlock [usertype] *lock @@ got struct spinlock [noderef] __rcu * @@
kernel/fork.c:2077:31: sparse: expected struct spinlock [usertype] *lock
kernel/fork.c:2077:31: sparse: got struct spinlock [noderef] __rcu *
kernel/fork.c:2081:33: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected struct spinlock [usertype] *lock @@ got struct spinlock [noderef] __rcu * @@
kernel/fork.c:2081:33: sparse: expected struct spinlock [usertype] *lock
kernel/fork.c:2081:33: sparse: got struct spinlock [noderef] __rcu *
kernel/fork.c:2403:32: sparse: sparse: incorrect type in assignment (different address spaces) @@ expected struct task_struct [noderef] __rcu *real_parent @@ got struct task_struct *task @@
kernel/fork.c:2403:32: sparse: expected struct task_struct [noderef] __rcu *real_parent
kernel/fork.c:2403:32: sparse: got struct task_struct *task
>> kernel/fork.c:2407:17: sparse: sparse: incorrect type in assignment (different address spaces) @@ expected struct task_struct [noderef] __rcu *caba @@ got struct task_struct *task @@
kernel/fork.c:2407:17: sparse: expected struct task_struct [noderef] __rcu *caba
kernel/fork.c:2407:17: sparse: got struct task_struct *task
kernel/fork.c:2413:27: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected struct spinlock [usertype] *lock @@ got struct spinlock [noderef] __rcu * @@
kernel/fork.c:2413:27: sparse: expected struct spinlock [usertype] *lock
kernel/fork.c:2413:27: sparse: got struct spinlock [noderef] __rcu *
kernel/fork.c:2460:54: sparse: sparse: incorrect type in argument 2 (different address spaces) @@ expected struct list_head *head @@ got struct list_head [noderef] __rcu * @@
kernel/fork.c:2460:54: sparse: expected struct list_head *head
kernel/fork.c:2460:54: sparse: got struct list_head [noderef] __rcu *
kernel/fork.c:2461:51: sparse: sparse: incorrect type in argument 2 (different address spaces) @@ expected struct list_head *head @@ got struct list_head [noderef] __rcu * @@
kernel/fork.c:2461:51: sparse: expected struct list_head *head
kernel/fork.c:2461:51: sparse: got struct list_head [noderef] __rcu *
kernel/fork.c:2482:29: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected struct spinlock [usertype] *lock @@ got struct spinlock [noderef] __rcu * @@
kernel/fork.c:2482:29: sparse: expected struct spinlock [usertype] *lock
kernel/fork.c:2482:29: sparse: got struct spinlock [noderef] __rcu *
kernel/fork.c:2503:29: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected struct spinlock [usertype] *lock @@ got struct spinlock [noderef] __rcu * @@
kernel/fork.c:2503:29: sparse: expected struct spinlock [usertype] *lock
kernel/fork.c:2503:29: sparse: got struct spinlock [noderef] __rcu *
kernel/fork.c:2530:28: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected struct sighand_struct *sighand @@ got struct sighand_struct [noderef] __rcu *sighand @@
kernel/fork.c:2530:28: sparse: expected struct sighand_struct *sighand
kernel/fork.c:2530:28: sparse: got struct sighand_struct [noderef] __rcu *sighand
kernel/fork.c:2559:31: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected struct spinlock [usertype] *lock @@ got struct spinlock [noderef] __rcu * @@
kernel/fork.c:2559:31: sparse: expected struct spinlock [usertype] *lock
kernel/fork.c:2559:31: sparse: got struct spinlock [noderef] __rcu *
kernel/fork.c:2561:33: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected struct spinlock [usertype] *lock @@ got struct spinlock [noderef] __rcu * @@
kernel/fork.c:2561:33: sparse: expected struct spinlock [usertype] *lock
kernel/fork.c:2561:33: sparse: got struct spinlock [noderef] __rcu *
kernel/fork.c:2997:24: sparse: sparse: incorrect type in assignment (different address spaces) @@ expected struct task_struct *[assigned] parent @@ got struct task_struct [noderef] __rcu *real_parent @@
kernel/fork.c:2997:24: sparse: expected struct task_struct *[assigned] parent
kernel/fork.c:2997:24: sparse: got struct task_struct [noderef] __rcu *real_parent
kernel/fork.c:3078:43: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected struct refcount_struct const [usertype] *r @@ got struct refcount_struct [noderef] __rcu * @@
kernel/fork.c:3078:43: sparse: expected struct refcount_struct const [usertype] *r
kernel/fork.c:3078:43: sparse: got struct refcount_struct [noderef] __rcu *
kernel/fork.c:2122:22: sparse: sparse: dereference of noderef expression
kernel/fork.c: note: in included file (through include/uapi/asm-generic/bpf_perf_event.h, arch/loongarch/include/generated/uapi/asm/bpf_perf_event.h, ...):
include/linux/ptrace.h:210:45: sparse: sparse: incorrect type in argument 2 (different address spaces) @@ expected struct task_struct *new_parent @@ got struct task_struct [noderef] __rcu *parent @@
include/linux/ptrace.h:210:45: sparse: expected struct task_struct *new_parent
include/linux/ptrace.h:210:45: sparse: got struct task_struct [noderef] __rcu *parent
include/linux/ptrace.h:210:62: sparse: sparse: incorrect type in argument 3 (different address spaces) @@ expected struct cred const *ptracer_cred @@ got struct cred const [noderef] __rcu *ptracer_cred @@
include/linux/ptrace.h:210:62: sparse: expected struct cred const *ptracer_cred
include/linux/ptrace.h:210:62: sparse: got struct cred const [noderef] __rcu *ptracer_cred
kernel/fork.c:2458:59: sparse: sparse: dereference of noderef expression
kernel/fork.c:2459:59: sparse: sparse: dereference of noderef expression
kernel/fork.c:1090:23: sparse: sparse: incompatible types in comparison expression (different address spaces):
kernel/fork.c:1090:23: sparse: struct task_struct [noderef] __rcu *
kernel/fork.c:1090:23: sparse: struct task_struct *

vim +2407 kernel/fork.c

2355
2356 /*
2357 * Ensure that the cgroup subsystem policies allow the new process to be
2358 * forked. It should be noted that the new process's css_set can be changed
2359 * between here and cgroup_post_fork() if an organisation operation is in
2360 * progress.
2361 */
2362 retval = cgroup_can_fork(p, args);
2363 if (retval)
2364 goto bad_fork_put_pidfd;
2365
2366 /*
2367 * Now that the cgroups are pinned, re-clone the parent cgroup and put
2368 * the new task on the correct runqueue. All this *before* the task
2369 * becomes visible.
2370 *
2371 * This isn't part of ->can_fork() because while the re-cloning is
2372 * cgroup specific, it unconditionally needs to place the task on a
2373 * runqueue.
2374 */
2375 sched_cgroup_fork(p, args);
2376
2377 /*
2378 * From this point on we must avoid any synchronous user-space
2379 * communication until we take the tasklist-lock. In particular, we do
2380 * not want user-space to be able to predict the process start-time by
2381 * stalling fork(2) after we recorded the start_time but before it is
2382 * visible to the system.
2383 */
2384
2385 p->start_time = ktime_get_ns();
2386 p->start_boottime = ktime_get_boottime_ns();
2387
2388 /*
2389 * Make it visible to the rest of the system, but dont wake it up yet.
2390 * Need tasklist lock for parent etc handling!
2391 */
2392 write_lock_irq(&tasklist_lock);
2393
2394 /* CLONE_PARENT re-uses the old parent */
2395 if (clone_flags & (CLONE_PARENT|CLONE_THREAD)) {
2396 p->real_parent = current->real_parent;
2397 p->parent_exec_id = current->parent_exec_id;
2398 if (clone_flags & CLONE_THREAD)
2399 p->exit_signal = -1;
2400 else
2401 p->exit_signal = current->group_leader->exit_signal;
2402 } else {
2403 p->real_parent = current;
2404 p->parent_exec_id = current->self_exec_id;
2405 p->exit_signal = args->exit_signal;
2406 }
> 2407 p->caba = current;
2408
2409 klp_copy_process(p);
2410
2411 sched_core_fork(p);
2412
2413 spin_lock(&current->sighand->siglock);
2414
2415 /*
2416 * Copy seccomp details explicitly here, in case they were changed
2417 * before holding sighand lock.
2418 */
2419 copy_seccomp(p);
2420
2421 rv_task_fork(p);
2422
2423 rseq_fork(p, clone_flags);
2424
2425 /* Don't start children in a dying pid namespace */
2426 if (unlikely(!(ns_of_pid(pid)->pid_allocated & PIDNS_ADDING))) {
2427 retval = -ENOMEM;
2428 goto bad_fork_cancel_cgroup;
2429 }
2430
2431 /* Let kill terminate clone/fork in the middle */
2432 if (fatal_signal_pending(current)) {
2433 retval = -EINTR;
2434 goto bad_fork_cancel_cgroup;
2435 }
2436
2437 init_task_pid_links(p);
2438 if (likely(p->pid)) {
2439 ptrace_init_task(p, (clone_flags & CLONE_PTRACE) || trace);
2440
2441 init_task_pid(p, PIDTYPE_PID, pid);
2442 if (thread_group_leader(p)) {
2443 init_task_pid(p, PIDTYPE_TGID, pid);
2444 init_task_pid(p, PIDTYPE_PGID, task_pgrp(current));
2445 init_task_pid(p, PIDTYPE_SID, task_session(current));
2446
2447 if (is_child_reaper(pid)) {
2448 ns_of_pid(pid)->child_reaper = p;
2449 p->signal->flags |= SIGNAL_UNKILLABLE;
2450 }
2451 p->signal->shared_pending.signal = delayed.signal;
2452 p->signal->tty = tty_kref_get(current->signal->tty);
2453 /*
2454 * Inherit has_child_subreaper flag under the same
2455 * tasklist_lock with adding child to the process tree
2456 * for propagate_has_child_subreaper optimization.
2457 */
2458 p->signal->has_child_subreaper = p->real_parent->signal->has_child_subreaper ||
2459 p->real_parent->signal->is_child_subreaper;
2460 list_add_tail(&p->sibling, &p->real_parent->children);
2461 list_add_tail(&p->cabd, &p->caba->cabds);
2462 list_add_tail_rcu(&p->tasks, &init_task.tasks);
2463 attach_pid(p, PIDTYPE_TGID);
2464 attach_pid(p, PIDTYPE_PGID);
2465 attach_pid(p, PIDTYPE_SID);
2466 __this_cpu_inc(process_counts);
2467 } else {
2468 current->signal->nr_threads++;
2469 atomic_inc(&current->signal->live);
2470 refcount_inc(&current->signal->sigcnt);
2471 task_join_group_stop(p);
2472 list_add_tail_rcu(&p->thread_group,
2473 &p->group_leader->thread_group);
2474 list_add_tail_rcu(&p->thread_node,
2475 &p->signal->thread_head);
2476 }
2477 attach_pid(p, PIDTYPE_PID);
2478 nr_threads++;
2479 }
2480 total_forks++;
2481 hlist_del_init(&delayed.node);
2482 spin_unlock(&current->sighand->siglock);
2483 syscall_tracepoint_update(p);
2484 write_unlock_irq(&tasklist_lock);
2485
2486 if (pidfile)
2487 fd_install(pidfd, pidfile);
2488
2489 proc_fork_connector(p);
2490 sched_post_fork(p);
2491 cgroup_post_fork(p, args);
2492 perf_event_fork(p);
2493
2494 trace_task_newtask(p, clone_flags);
2495 uprobe_copy_process(p, clone_flags);
2496
2497 copy_oom_score_adj(clone_flags, p);
2498
2499 return p;
2500
2501 bad_fork_cancel_cgroup:
2502 sched_core_free(p);
2503 spin_unlock(&current->sighand->siglock);
2504 write_unlock_irq(&tasklist_lock);
2505 cgroup_cancel_fork(p, args);
2506 bad_fork_put_pidfd:
2507 if (clone_flags & CLONE_PIDFD) {
2508 fput(pidfile);
2509 put_unused_fd(pidfd);
2510 }
2511 bad_fork_free_pid:
2512 if (pid != &init_struct_pid)
2513 free_pid(pid);
2514 bad_fork_cleanup_thread:
2515 exit_thread(p);
2516 bad_fork_cleanup_io:
2517 if (p->io_context)
2518 exit_io_context(p);
2519 bad_fork_cleanup_namespaces:
2520 exit_task_namespaces(p);
2521 bad_fork_cleanup_mm:
2522 if (p->mm) {
2523 mm_clear_owner(p->mm, p);
2524 mmput(p->mm);
2525 }
2526 bad_fork_cleanup_signal:
2527 if (!(clone_flags & CLONE_THREAD))
2528 free_signal_struct(p->signal);
2529 bad_fork_cleanup_sighand:
2530 __cleanup_sighand(p->sighand);
2531 bad_fork_cleanup_fs:
2532 exit_fs(p); /* blocking */
2533 bad_fork_cleanup_files:
2534 exit_files(p); /* blocking */
2535 bad_fork_cleanup_semundo:
2536 exit_sem(p);
2537 bad_fork_cleanup_security:
2538 security_task_free(p);
2539 bad_fork_cleanup_audit:
2540 audit_free(p);
2541 bad_fork_cleanup_perf:
2542 perf_event_free_task(p);
2543 bad_fork_cleanup_policy:
2544 lockdep_free_task(p);
2545 #ifdef CONFIG_NUMA
2546 mpol_put(p->mempolicy);
2547 #endif
2548 bad_fork_cleanup_delayacct:
2549 delayacct_tsk_free(p);
2550 bad_fork_cleanup_count:
2551 dec_rlimit_ucounts(task_ucounts(p), UCOUNT_RLIMIT_NPROC, 1);
2552 exit_creds(p);
2553 bad_fork_free:
2554 WRITE_ONCE(p->__state, TASK_DEAD);
2555 exit_task_stack_account(p);
2556 put_task_stack(p);
2557 delayed_free_task(p);
2558 fork_out:
2559 spin_lock_irq(&current->sighand->siglock);
2560 hlist_del_init(&delayed.node);
2561 spin_unlock_irq(&current->sighand->siglock);
2562 return ERR_PTR(retval);
2563 }
2564

--
0-DAY CI Kernel Test Service
https://01.org/lkp

2022-09-09 01:06:06

by kernel test robot

Subject: Re: [PATCH v3 1/2] Add CABA tree to task_struct

Hi Pavel,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on shuah-kselftest/next]
[also build test WARNING on kees/for-next/execve tip/sched/core linus/master v6.0-rc4 next-20220908]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url: https://github.com/intel-lab-lkp/linux/commits/Pavel-Tikhomirov/Introduce-CABA-helper-process-tree/20220908-220639
base: https://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest.git next
config: microblaze-randconfig-s053-20220907 (https://download.01.org/0day-ci/archive/20220909/[email protected]/config)
compiler: microblaze-linux-gcc (GCC) 12.1.0
reproduce:
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# apt-get install sparse
# sparse version: v0.6.4-39-gce1a6720-dirty
# https://github.com/intel-lab-lkp/linux/commit/17a897a33137d4f49f99c8be8d619f6f711fccdb
git remote add linux-review https://github.com/intel-lab-lkp/linux
git fetch --no-tags linux-review Pavel-Tikhomirov/Introduce-CABA-helper-process-tree/20220908-220639
git checkout 17a897a33137d4f49f99c8be8d619f6f711fccdb
# save the config file
mkdir build_dir && cp config build_dir/.config
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__' O=build_dir ARCH=microblaze SHELL=/bin/bash

If you fix the issue, kindly add following tag where applicable
Reported-by: kernel test robot <[email protected]>

sparse warnings: (new ones prefixed by >>)
kernel/fork.c:1307:22: sparse: sparse: incorrect type in assignment (different address spaces) @@ expected struct file *[assigned] old_exe_file @@ got struct file [noderef] __rcu * @@
kernel/fork.c:1307:22: sparse: expected struct file *[assigned] old_exe_file
kernel/fork.c:1307:22: sparse: got struct file [noderef] __rcu *
kernel/fork.c:1638:38: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected struct refcount_struct [usertype] *r @@ got struct refcount_struct [noderef] __rcu * @@
kernel/fork.c:1638:38: sparse: expected struct refcount_struct [usertype] *r
kernel/fork.c:1638:38: sparse: got struct refcount_struct [noderef] __rcu *
kernel/fork.c:1647:31: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected struct spinlock [usertype] *lock @@ got struct spinlock [noderef] __rcu * @@
kernel/fork.c:1647:31: sparse: expected struct spinlock [usertype] *lock
kernel/fork.c:1647:31: sparse: got struct spinlock [noderef] __rcu *
kernel/fork.c:1648:36: sparse: sparse: incorrect type in argument 2 (different address spaces) @@ expected void const * @@ got struct k_sigaction [noderef] __rcu * @@
kernel/fork.c:1648:36: sparse: expected void const *
kernel/fork.c:1648:36: sparse: got struct k_sigaction [noderef] __rcu *
kernel/fork.c:1649:33: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected struct spinlock [usertype] *lock @@ got struct spinlock [noderef] __rcu * @@
kernel/fork.c:1649:33: sparse: expected struct spinlock [usertype] *lock
kernel/fork.c:1649:33: sparse: got struct spinlock [noderef] __rcu *
kernel/fork.c:2077:31: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected struct spinlock [usertype] *lock @@ got struct spinlock [noderef] __rcu * @@
kernel/fork.c:2077:31: sparse: expected struct spinlock [usertype] *lock
kernel/fork.c:2077:31: sparse: got struct spinlock [noderef] __rcu *
kernel/fork.c:2081:33: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected struct spinlock [usertype] *lock @@ got struct spinlock [noderef] __rcu * @@
kernel/fork.c:2081:33: sparse: expected struct spinlock [usertype] *lock
kernel/fork.c:2081:33: sparse: got struct spinlock [noderef] __rcu *
kernel/fork.c:2403:32: sparse: sparse: incorrect type in assignment (different address spaces) @@ expected struct task_struct [noderef] __rcu *real_parent @@ got struct task_struct *register [addressable] [toplevel] current @@
kernel/fork.c:2403:32: sparse: expected struct task_struct [noderef] __rcu *real_parent
kernel/fork.c:2403:32: sparse: got struct task_struct *register [addressable] [toplevel] current
>> kernel/fork.c:2407:17: sparse: sparse: incorrect type in assignment (different address spaces) @@ expected struct task_struct [noderef] __rcu *caba @@ got struct task_struct *register [addressable] [toplevel] current @@
kernel/fork.c:2407:17: sparse: expected struct task_struct [noderef] __rcu *caba
kernel/fork.c:2407:17: sparse: got struct task_struct *register [addressable] [toplevel] current
kernel/fork.c:2413:27: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected struct spinlock [usertype] *lock @@ got struct spinlock [noderef] __rcu * @@
kernel/fork.c:2413:27: sparse: expected struct spinlock [usertype] *lock
kernel/fork.c:2413:27: sparse: got struct spinlock [noderef] __rcu *
kernel/fork.c:2460:54: sparse: sparse: incorrect type in argument 2 (different address spaces) @@ expected struct list_head *head @@ got struct list_head [noderef] __rcu * @@
kernel/fork.c:2460:54: sparse: expected struct list_head *head
kernel/fork.c:2460:54: sparse: got struct list_head [noderef] __rcu *
kernel/fork.c:2461:51: sparse: sparse: incorrect type in argument 2 (different address spaces) @@ expected struct list_head *head @@ got struct list_head [noderef] __rcu * @@
kernel/fork.c:2461:51: sparse: expected struct list_head *head
kernel/fork.c:2461:51: sparse: got struct list_head [noderef] __rcu *
kernel/fork.c:2482:29: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected struct spinlock [usertype] *lock @@ got struct spinlock [noderef] __rcu * @@
kernel/fork.c:2482:29: sparse: expected struct spinlock [usertype] *lock
kernel/fork.c:2482:29: sparse: got struct spinlock [noderef] __rcu *
kernel/fork.c:2503:29: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected struct spinlock [usertype] *lock @@ got struct spinlock [noderef] __rcu * @@
kernel/fork.c:2503:29: sparse: expected struct spinlock [usertype] *lock
kernel/fork.c:2503:29: sparse: got struct spinlock [noderef] __rcu *
kernel/fork.c:2530:28: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected struct sighand_struct *sighand @@ got struct sighand_struct [noderef] __rcu *sighand @@
kernel/fork.c:2530:28: sparse: expected struct sighand_struct *sighand
kernel/fork.c:2530:28: sparse: got struct sighand_struct [noderef] __rcu *sighand
kernel/fork.c:2559:31: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected struct spinlock [usertype] *lock @@ got struct spinlock [noderef] __rcu * @@
kernel/fork.c:2559:31: sparse: expected struct spinlock [usertype] *lock
kernel/fork.c:2559:31: sparse: got struct spinlock [noderef] __rcu *
kernel/fork.c:2561:33: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected struct spinlock [usertype] *lock @@ got struct spinlock [noderef] __rcu * @@
kernel/fork.c:2561:33: sparse: expected struct spinlock [usertype] *lock
kernel/fork.c:2561:33: sparse: got struct spinlock [noderef] __rcu *
kernel/fork.c:2997:24: sparse: sparse: incorrect type in assignment (different address spaces) @@ expected struct task_struct *[assigned] parent @@ got struct task_struct [noderef] __rcu *real_parent @@
kernel/fork.c:2997:24: sparse: expected struct task_struct *[assigned] parent
kernel/fork.c:2997:24: sparse: got struct task_struct [noderef] __rcu *real_parent
kernel/fork.c:3078:43: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected struct refcount_struct const [usertype] *r @@ got struct refcount_struct [noderef] __rcu * @@
kernel/fork.c:3078:43: sparse: expected struct refcount_struct const [usertype] *r
kernel/fork.c:3078:43: sparse: got struct refcount_struct [noderef] __rcu *
kernel/fork.c:1742:9: sparse: sparse: dereference of noderef expression
kernel/fork.c:2122:22: sparse: sparse: dereference of noderef expression
kernel/fork.c: note: in included file (through include/uapi/asm-generic/bpf_perf_event.h, arch/microblaze/include/generated/uapi/asm/bpf_perf_event.h, ...):
include/linux/ptrace.h:210:45: sparse: sparse: incorrect type in argument 2 (different address spaces) @@ expected struct task_struct *new_parent @@ got struct task_struct [noderef] __rcu *parent @@
include/linux/ptrace.h:210:45: sparse: expected struct task_struct *new_parent
include/linux/ptrace.h:210:45: sparse: got struct task_struct [noderef] __rcu *parent
include/linux/ptrace.h:210:62: sparse: sparse: incorrect type in argument 3 (different address spaces) @@ expected struct cred const *ptracer_cred @@ got struct cred const [noderef] __rcu *ptracer_cred @@
include/linux/ptrace.h:210:62: sparse: expected struct cred const *ptracer_cred
include/linux/ptrace.h:210:62: sparse: got struct cred const [noderef] __rcu *ptracer_cred
kernel/fork.c:2458:59: sparse: sparse: dereference of noderef expression
kernel/fork.c:2459:59: sparse: sparse: dereference of noderef expression

vim +2407 kernel/fork.c

2355
2356 /*
2357 * Ensure that the cgroup subsystem policies allow the new process to be
2358 * forked. It should be noted that the new process's css_set can be changed
2359 * between here and cgroup_post_fork() if an organisation operation is in
2360 * progress.
2361 */
2362 retval = cgroup_can_fork(p, args);
2363 if (retval)
2364 goto bad_fork_put_pidfd;
2365
2366 /*
2367 * Now that the cgroups are pinned, re-clone the parent cgroup and put
2368 * the new task on the correct runqueue. All this *before* the task
2369 * becomes visible.
2370 *
2371 * This isn't part of ->can_fork() because while the re-cloning is
2372 * cgroup specific, it unconditionally needs to place the task on a
2373 * runqueue.
2374 */
2375 sched_cgroup_fork(p, args);
2376
2377 /*
2378 * From this point on we must avoid any synchronous user-space
2379 * communication until we take the tasklist-lock. In particular, we do
2380 * not want user-space to be able to predict the process start-time by
2381 * stalling fork(2) after we recorded the start_time but before it is
2382 * visible to the system.
2383 */
2384
2385 p->start_time = ktime_get_ns();
2386 p->start_boottime = ktime_get_boottime_ns();
2387
2388 /*
2389 * Make it visible to the rest of the system, but dont wake it up yet.
2390 * Need tasklist lock for parent etc handling!
2391 */
2392 write_lock_irq(&tasklist_lock);
2393
2394 /* CLONE_PARENT re-uses the old parent */
2395 if (clone_flags & (CLONE_PARENT|CLONE_THREAD)) {
2396 p->real_parent = current->real_parent;
2397 p->parent_exec_id = current->parent_exec_id;
2398 if (clone_flags & CLONE_THREAD)
2399 p->exit_signal = -1;
2400 else
2401 p->exit_signal = current->group_leader->exit_signal;
2402 } else {
2403 p->real_parent = current;
2404 p->parent_exec_id = current->self_exec_id;
2405 p->exit_signal = args->exit_signal;
2406 }
> 2407 p->caba = current;
2408
2409 klp_copy_process(p);
2410
2411 sched_core_fork(p);
2412
2413 spin_lock(&current->sighand->siglock);
2414
2415 /*
2416 * Copy seccomp details explicitly here, in case they were changed
2417 * before holding sighand lock.
2418 */
2419 copy_seccomp(p);
2420
2421 rv_task_fork(p);
2422
2423 rseq_fork(p, clone_flags);
2424
2425 /* Don't start children in a dying pid namespace */
2426 if (unlikely(!(ns_of_pid(pid)->pid_allocated & PIDNS_ADDING))) {
2427 retval = -ENOMEM;
2428 goto bad_fork_cancel_cgroup;
2429 }
2430
2431 /* Let kill terminate clone/fork in the middle */
2432 if (fatal_signal_pending(current)) {
2433 retval = -EINTR;
2434 goto bad_fork_cancel_cgroup;
2435 }
2436
2437 init_task_pid_links(p);
2438 if (likely(p->pid)) {
2439 ptrace_init_task(p, (clone_flags & CLONE_PTRACE) || trace);
2440
2441 init_task_pid(p, PIDTYPE_PID, pid);
2442 if (thread_group_leader(p)) {
2443 init_task_pid(p, PIDTYPE_TGID, pid);
2444 init_task_pid(p, PIDTYPE_PGID, task_pgrp(current));
2445 init_task_pid(p, PIDTYPE_SID, task_session(current));
2446
2447 if (is_child_reaper(pid)) {
2448 ns_of_pid(pid)->child_reaper = p;
2449 p->signal->flags |= SIGNAL_UNKILLABLE;
2450 }
2451 p->signal->shared_pending.signal = delayed.signal;
2452 p->signal->tty = tty_kref_get(current->signal->tty);
2453 /*
2454 * Inherit has_child_subreaper flag under the same
2455 * tasklist_lock with adding child to the process tree
2456 * for propagate_has_child_subreaper optimization.
2457 */
2458 p->signal->has_child_subreaper = p->real_parent->signal->has_child_subreaper ||
2459 p->real_parent->signal->is_child_subreaper;
2460 list_add_tail(&p->sibling, &p->real_parent->children);
2461 list_add_tail(&p->cabd, &p->caba->cabds);
2462 list_add_tail_rcu(&p->tasks, &init_task.tasks);
2463 attach_pid(p, PIDTYPE_TGID);
2464 attach_pid(p, PIDTYPE_PGID);
2465 attach_pid(p, PIDTYPE_SID);
2466 __this_cpu_inc(process_counts);
2467 } else {
2468 current->signal->nr_threads++;
2469 atomic_inc(&current->signal->live);
2470 refcount_inc(&current->signal->sigcnt);
2471 task_join_group_stop(p);
2472 list_add_tail_rcu(&p->thread_group,
2473 &p->group_leader->thread_group);
2474 list_add_tail_rcu(&p->thread_node,
2475 &p->signal->thread_head);
2476 }
2477 attach_pid(p, PIDTYPE_PID);
2478 nr_threads++;
2479 }
2480 total_forks++;
2481 hlist_del_init(&delayed.node);
2482 spin_unlock(&current->sighand->siglock);
2483 syscall_tracepoint_update(p);
2484 write_unlock_irq(&tasklist_lock);
2485
2486 if (pidfile)
2487 fd_install(pidfd, pidfile);
2488
2489 proc_fork_connector(p);
2490 sched_post_fork(p);
2491 cgroup_post_fork(p, args);
2492 perf_event_fork(p);
2493
2494 trace_task_newtask(p, clone_flags);
2495 uprobe_copy_process(p, clone_flags);
2496
2497 copy_oom_score_adj(clone_flags, p);
2498
2499 return p;
2500
2501 bad_fork_cancel_cgroup:
2502 sched_core_free(p);
2503 spin_unlock(&current->sighand->siglock);
2504 write_unlock_irq(&tasklist_lock);
2505 cgroup_cancel_fork(p, args);
2506 bad_fork_put_pidfd:
2507 if (clone_flags & CLONE_PIDFD) {
2508 fput(pidfile);
2509 put_unused_fd(pidfd);
2510 }
2511 bad_fork_free_pid:
2512 if (pid != &init_struct_pid)
2513 free_pid(pid);
2514 bad_fork_cleanup_thread:
2515 exit_thread(p);
2516 bad_fork_cleanup_io:
2517 if (p->io_context)
2518 exit_io_context(p);
2519 bad_fork_cleanup_namespaces:
2520 exit_task_namespaces(p);
2521 bad_fork_cleanup_mm:
2522 if (p->mm) {
2523 mm_clear_owner(p->mm, p);
2524 mmput(p->mm);
2525 }
2526 bad_fork_cleanup_signal:
2527 if (!(clone_flags & CLONE_THREAD))
2528 free_signal_struct(p->signal);
2529 bad_fork_cleanup_sighand:
2530 __cleanup_sighand(p->sighand);
2531 bad_fork_cleanup_fs:
2532 exit_fs(p); /* blocking */
2533 bad_fork_cleanup_files:
2534 exit_files(p); /* blocking */
2535 bad_fork_cleanup_semundo:
2536 exit_sem(p);
2537 bad_fork_cleanup_security:
2538 security_task_free(p);
2539 bad_fork_cleanup_audit:
2540 audit_free(p);
2541 bad_fork_cleanup_perf:
2542 perf_event_free_task(p);
2543 bad_fork_cleanup_policy:
2544 lockdep_free_task(p);
2545 #ifdef CONFIG_NUMA
2546 mpol_put(p->mempolicy);
2547 #endif
2548 bad_fork_cleanup_delayacct:
2549 delayacct_tsk_free(p);
2550 bad_fork_cleanup_count:
2551 dec_rlimit_ucounts(task_ucounts(p), UCOUNT_RLIMIT_NPROC, 1);
2552 exit_creds(p);
2553 bad_fork_free:
2554 WRITE_ONCE(p->__state, TASK_DEAD);
2555 exit_task_stack_account(p);
2556 put_task_stack(p);
2557 delayed_free_task(p);
2558 fork_out:
2559 spin_lock_irq(&current->sighand->siglock);
2560 hlist_del_init(&delayed.node);
2561 spin_unlock_irq(&current->sighand->siglock);
2562 return ERR_PTR(retval);
2563 }
2564

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0-DAY CI Kernel Test Service
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2022-09-11 19:37:56

by kernel test robot

Subject: Re: [PATCH v3 1/2] Add CABA tree to task_struct

Hi Pavel,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on shuah-kselftest/next]
[also build test WARNING on kees/for-next/execve tip/sched/core linus/master v6.0-rc4 next-20220909]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url: https://github.com/intel-lab-lkp/linux/commits/Pavel-Tikhomirov/Introduce-CABA-helper-process-tree/20220908-220639
base: https://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest.git next
config: ia64-randconfig-s041-20220911 (https://download.01.org/0day-ci/archive/20220912/[email protected]/config)
compiler: ia64-linux-gcc (GCC) 12.1.0
reproduce:
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# apt-get install sparse
# sparse version: v0.6.4-39-gce1a6720-dirty
# https://github.com/intel-lab-lkp/linux/commit/17a897a33137d4f49f99c8be8d619f6f711fccdb
git remote add linux-review https://github.com/intel-lab-lkp/linux
git fetch --no-tags linux-review Pavel-Tikhomirov/Introduce-CABA-helper-process-tree/20220908-220639
git checkout 17a897a33137d4f49f99c8be8d619f6f711fccdb
# save the config file
mkdir build_dir && cp config build_dir/.config
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__' O=build_dir ARCH=ia64 SHELL=/bin/bash arch/ia64/kernel/

If you fix the issue, kindly add following tag where applicable
Reported-by: kernel test robot <[email protected]>

sparse warnings: (new ones prefixed by >>)
arch/ia64/kernel/mca.c:504:1: sparse: sparse: symbol 'search_mca_table' was not declared. Should it be static?
arch/ia64/kernel/mca.c:607:1: sparse: sparse: symbol 'ia64_mca_register_cpev' was not declared. Should it be static?
arch/ia64/kernel/mca.c:831:5: sparse: sparse: symbol 'ia64_mca_ucmc_extension' was not declared. Should it be static?
arch/ia64/kernel/mca.c:1793:36: sparse: sparse: incorrect type in assignment (different address spaces) @@ expected struct task_struct [noderef] __rcu *real_parent @@ got struct task_struct *group_leader @@
arch/ia64/kernel/mca.c:1793:36: sparse: expected struct task_struct [noderef] __rcu *real_parent
arch/ia64/kernel/mca.c:1793:36: sparse: got struct task_struct *group_leader
>> arch/ia64/kernel/mca.c:1796:17: sparse: sparse: incorrect type in assignment (different address spaces) @@ expected struct task_struct [noderef] __rcu *caba @@ got struct task_struct *p @@
arch/ia64/kernel/mca.c:1796:17: sparse: expected struct task_struct [noderef] __rcu *caba
arch/ia64/kernel/mca.c:1796:17: sparse: got struct task_struct *p
arch/ia64/kernel/mca.c:2106:43: sparse: sparse: Using plain integer as NULL pointer

vim +1796 arch/ia64/kernel/mca.c

1770
1771 /* Minimal format of the MCA/INIT stacks. The pseudo processes that run on
1772 * these stacks can never sleep, they cannot return from the kernel to user
1773 * space, they do not appear in a normal ps listing. So there is no need to
1774 * format most of the fields.
1775 */
1776
1777 static void
1778 format_mca_init_stack(void *mca_data, unsigned long offset,
1779 const char *type, int cpu)
1780 {
1781 struct task_struct *p = (struct task_struct *)((char *)mca_data + offset);
1782 struct thread_info *ti;
1783 memset(p, 0, KERNEL_STACK_SIZE);
1784 ti = task_thread_info(p);
1785 ti->flags = _TIF_MCA_INIT;
1786 ti->preempt_count = 1;
1787 ti->task = p;
1788 ti->cpu = cpu;
1789 p->stack = ti;
1790 p->__state = TASK_UNINTERRUPTIBLE;
1791 cpumask_set_cpu(cpu, &p->cpus_mask);
1792 INIT_LIST_HEAD(&p->tasks);
1793 p->parent = p->real_parent = p->group_leader = p;
1794 INIT_LIST_HEAD(&p->children);
1795 INIT_LIST_HEAD(&p->sibling);
> 1796 p->caba = p;
1797 INIT_LIST_HEAD(&p->cabds);
1798 INIT_LIST_HEAD(&p->cabd);
1799 strncpy(p->comm, type, sizeof(p->comm)-1);
1800 }
1801

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