run_helper and run_helper_thread had arguments which were the same in
all callers. run_helper's stack_out was always NULL and
run_helper_thread's stack_order was always 0. These are now gone, and
the constants folded into the code.
Also fixed leaks of the helper stack in the AIO and SIGIO code.
Signed-off-by: Jeff Dike <[email protected]>
--
arch/um/drivers/chan_user.c | 2 +-
arch/um/drivers/harddog_user.c | 2 +-
arch/um/drivers/net_user.c | 2 +-
arch/um/drivers/port_user.c | 2 +-
arch/um/drivers/slip_user.c | 2 +-
arch/um/drivers/slirp_user.c | 2 +-
arch/um/drivers/xterm.c | 2 +-
arch/um/include/os.h | 6 ++----
arch/um/os-Linux/aio.c | 11 ++++++-----
arch/um/os-Linux/drivers/ethertap_user.c | 2 +-
arch/um/os-Linux/drivers/tuntap_user.c | 2 +-
arch/um/os-Linux/helper.c | 19 +++++++------------
arch/um/os-Linux/sigio.c | 19 ++++++++++++-------
13 files changed, 36 insertions(+), 37 deletions(-)
Index: linux-2.6.21-mm/arch/um/drivers/harddog_user.c
===================================================================
--- linux-2.6.21-mm.orig/arch/um/drivers/harddog_user.c 2007-06-13 17:13:42.000000000 -0400
+++ linux-2.6.21-mm/arch/um/drivers/harddog_user.c 2007-06-13 18:44:41.000000000 -0400
@@ -68,7 +68,7 @@ int start_watchdog(int *in_fd_ret, int *
args = pid_args;
}
- pid = run_helper(pre_exec, &data, args, NULL);
+ pid = run_helper(pre_exec, &data, args);
os_close_file(out_fds[0]);
os_close_file(in_fds[1]);
Index: linux-2.6.21-mm/arch/um/drivers/net_user.c
===================================================================
--- linux-2.6.21-mm.orig/arch/um/drivers/net_user.c 2007-06-13 17:13:42.000000000 -0400
+++ linux-2.6.21-mm/arch/um/drivers/net_user.c 2007-06-14 11:20:36.000000000 -0400
@@ -187,7 +187,7 @@ static int change_tramp(char **argv, cha
}
pe_data.close_me = fds[0];
pe_data.stdout = fds[1];
- pid = run_helper(change_pre_exec, &pe_data, argv, NULL);
+ pid = run_helper(change_pre_exec, &pe_data, argv);
if (pid > 0) /* Avoid hang as we won't get data in failure case. */
read_output(fds[0], output, output_len);
Index: linux-2.6.21-mm/arch/um/drivers/port_user.c
===================================================================
--- linux-2.6.21-mm.orig/arch/um/drivers/port_user.c 2007-06-13 17:13:42.000000000 -0400
+++ linux-2.6.21-mm/arch/um/drivers/port_user.c 2007-06-14 11:20:36.000000000 -0400
@@ -188,7 +188,7 @@ int port_connection(int fd, int *socket,
{ .sock_fd = new,
.pipe_fd = socket[1] });
- err = run_helper(port_pre_exec, &data, argv, NULL);
+ err = run_helper(port_pre_exec, &data, argv);
if(err < 0)
goto out_shutdown;
Index: linux-2.6.21-mm/arch/um/drivers/slip_user.c
===================================================================
--- linux-2.6.21-mm.orig/arch/um/drivers/slip_user.c 2007-06-13 17:13:42.000000000 -0400
+++ linux-2.6.21-mm/arch/um/drivers/slip_user.c 2007-06-14 11:20:36.000000000 -0400
@@ -85,7 +85,7 @@ static int slip_tramp(char **argv, int f
pe_data.stdin = fd;
pe_data.stdout = fds[1];
pe_data.close_me = fds[0];
- err = run_helper(slip_pre_exec, &pe_data, argv, NULL);
+ err = run_helper(slip_pre_exec, &pe_data, argv);
if(err < 0)
goto out_close;
pid = err;
Index: linux-2.6.21-mm/arch/um/drivers/slirp_user.c
===================================================================
--- linux-2.6.21-mm.orig/arch/um/drivers/slirp_user.c 2007-06-13 17:13:42.000000000 -0400
+++ linux-2.6.21-mm/arch/um/drivers/slirp_user.c 2007-06-13 18:44:41.000000000 -0400
@@ -42,7 +42,7 @@ static int slirp_tramp(char **argv, int
pe_data.stdin = fd;
pe_data.stdout = fd;
- pid = run_helper(slirp_pre_exec, &pe_data, argv, NULL);
+ pid = run_helper(slirp_pre_exec, &pe_data, argv);
return(pid);
}
Index: linux-2.6.21-mm/arch/um/drivers/xterm.c
===================================================================
--- linux-2.6.21-mm.orig/arch/um/drivers/xterm.c 2007-06-13 17:13:42.000000000 -0400
+++ linux-2.6.21-mm/arch/um/drivers/xterm.c 2007-06-13 18:44:41.000000000 -0400
@@ -132,7 +132,7 @@ static int xterm_open(int input, int out
}
sprintf(title, data->title, data->device);
- pid = run_helper(NULL, NULL, argv, NULL);
+ pid = run_helper(NULL, NULL, argv);
if (pid < 0) {
err = pid;
printk(UM_KERN_ERR "xterm_open : run_helper failed, "
Index: linux-2.6.21-mm/arch/um/include/os.h
===================================================================
--- linux-2.6.21-mm.orig/arch/um/include/os.h 2007-06-13 17:13:42.000000000 -0400
+++ linux-2.6.21-mm/arch/um/include/os.h 2007-06-13 18:44:41.000000000 -0400
@@ -239,11 +239,9 @@ extern unsigned long __do_user_copy(void
/* execvp.c */
extern int execvp_noalloc(char *buf, const char *file, char *const argv[]);
/* helper.c */
-extern int run_helper(void (*pre_exec)(void *), void *pre_data, char **argv,
- unsigned long *stack_out);
+extern int run_helper(void (*pre_exec)(void *), void *pre_data, char **argv);
extern int run_helper_thread(int (*proc)(void *), void *arg,
- unsigned int flags, unsigned long *stack_out,
- int stack_order);
+ unsigned int flags, unsigned long *stack_out);
extern int helper_wait(int pid);
Index: linux-2.6.21-mm/arch/um/os-Linux/aio.c
===================================================================
--- linux-2.6.21-mm.orig/arch/um/os-Linux/aio.c 2007-06-13 17:13:42.000000000 -0400
+++ linux-2.6.21-mm/arch/um/os-Linux/aio.c 2007-06-13 18:44:41.000000000 -0400
@@ -177,6 +177,7 @@ static int do_not_aio(struct aio_thread_
static int aio_req_fd_r = -1;
static int aio_req_fd_w = -1;
static int aio_pid = -1;
+static unsigned long aio_stack;
static int not_aio_thread(void *arg)
{
@@ -212,7 +213,6 @@ static int not_aio_thread(void *arg)
static int init_aio_24(void)
{
- unsigned long stack;
int fds[2], err;
err = os_pipe(fds, 1, 1);
@@ -227,7 +227,7 @@ static int init_aio_24(void)
goto out_close_pipe;
err = run_helper_thread(not_aio_thread, NULL,
- CLONE_FILES | CLONE_VM | SIGCHLD, &stack, 0);
+ CLONE_FILES | CLONE_VM | SIGCHLD, &aio_stack);
if(err < 0)
goto out_close_pipe;
@@ -252,7 +252,6 @@ out:
#define DEFAULT_24_AIO 0
static int init_aio_26(void)
{
- unsigned long stack;
int err;
if(io_setup(256, &ctx)){
@@ -263,7 +262,7 @@ static int init_aio_26(void)
}
err = run_helper_thread(aio_thread, NULL,
- CLONE_FILES | CLONE_VM | SIGCHLD, &stack, 0);
+ CLONE_FILES | CLONE_VM | SIGCHLD, &aio_stack);
if(err < 0)
return err;
@@ -365,8 +364,10 @@ __initcall(init_aio);
static void exit_aio(void)
{
- if(aio_pid != -1)
+ if (aio_pid != -1) {
os_kill_process(aio_pid, 1);
+ free_stack(aio_stack, 0);
+ }
}
__uml_exitcall(exit_aio);
Index: linux-2.6.21-mm/arch/um/os-Linux/drivers/ethertap_user.c
===================================================================
--- linux-2.6.21-mm.orig/arch/um/os-Linux/drivers/ethertap_user.c 2007-06-13 17:13:42.000000000 -0400
+++ linux-2.6.21-mm/arch/um/os-Linux/drivers/ethertap_user.c 2007-06-14 11:20:36.000000000 -0400
@@ -117,7 +117,7 @@ static int etap_tramp(char *dev, char *g
pe_data.control_remote = control_remote;
pe_data.control_me = control_me;
pe_data.data_me = data_me;
- pid = run_helper(etap_pre_exec, &pe_data, args, NULL);
+ pid = run_helper(etap_pre_exec, &pe_data, args);
if(pid < 0)
err = pid;
Index: linux-2.6.21-mm/arch/um/os-Linux/drivers/tuntap_user.c
===================================================================
--- linux-2.6.21-mm.orig/arch/um/os-Linux/drivers/tuntap_user.c 2007-06-13 17:13:42.000000000 -0400
+++ linux-2.6.21-mm/arch/um/os-Linux/drivers/tuntap_user.c 2007-06-13 18:44:41.000000000 -0400
@@ -83,7 +83,7 @@ static int tuntap_open_tramp(char *gate,
data.stdout = remote;
data.close_me = me;
- pid = run_helper(tuntap_pre_exec, &data, argv, NULL);
+ pid = run_helper(tuntap_pre_exec, &data, argv);
if(pid < 0)
return -pid;
Index: linux-2.6.21-mm/arch/um/os-Linux/helper.c
===================================================================
--- linux-2.6.21-mm.orig/arch/um/os-Linux/helper.c 2007-06-13 17:13:42.000000000 -0400
+++ linux-2.6.21-mm/arch/um/os-Linux/helper.c 2007-06-14 11:20:36.000000000 -0400
@@ -44,17 +44,13 @@ static int helper_child(void *arg)
/* Returns either the pid of the child process we run or -E* on failure.
* XXX The alloc_stack here breaks if this is called in the tracing thread, so
* we need to receive a preallocated stack (a local buffer is ok). */
-int run_helper(void (*pre_exec)(void *), void *pre_data, char **argv,
- unsigned long *stack_out)
+int run_helper(void (*pre_exec)(void *), void *pre_data, char **argv)
{
struct helper_data data;
unsigned long stack, sp;
int pid, fds[2], ret, n;
- if ((stack_out != NULL) && (*stack_out != 0))
- stack = *stack_out;
- else
- stack = alloc_stack(0, __cant_sleep());
+ stack = alloc_stack(0, __cant_sleep());
if (stack == 0)
return -ENOMEM;
@@ -113,22 +109,21 @@ out_close:
close(fds[1]);
close(fds[0]);
out_free:
- if ((stack_out == NULL) || (*stack_out == 0))
- free_stack(stack, 0);
+ free_stack(stack, 0);
return ret;
}
int run_helper_thread(int (*proc)(void *), void *arg, unsigned int flags,
- unsigned long *stack_out, int stack_order)
+ unsigned long *stack_out)
{
unsigned long stack, sp;
int pid, status, err;
- stack = alloc_stack(stack_order, __cant_sleep());
+ stack = alloc_stack(0, __cant_sleep());
if (stack == 0)
return -ENOMEM;
- sp = stack + (UM_KERN_PAGE_SIZE << stack_order) - sizeof(void *);
+ sp = stack + UM_KERN_PAGE_SIZE - sizeof(void *);
pid = clone(proc, (void *) sp, flags | SIGCHLD, arg);
if (pid < 0) {
err = -errno;
@@ -147,7 +142,7 @@ int run_helper_thread(int (*proc)(void *
if (!WIFEXITED(status) || (WEXITSTATUS(status) != 0))
printk("run_helper_thread - thread returned status "
"0x%x\n", status);
- free_stack(stack, stack_order);
+ free_stack(stack, 0);
} else
*stack_out = stack;
return pid;
Index: linux-2.6.21-mm/arch/um/os-Linux/sigio.c
===================================================================
--- linux-2.6.21-mm.orig/arch/um/os-Linux/sigio.c 2007-06-13 17:13:42.000000000 -0400
+++ linux-2.6.21-mm/arch/um/os-Linux/sigio.c 2007-06-14 11:20:36.000000000 -0400
@@ -26,6 +26,7 @@
* exitcall.
*/
static int write_sigio_pid = -1;
+static unsigned long write_sigio_stack;
/* These arrays are initialized before the sigio thread is started, and
* the descriptors closed after it is killed. So, it can't see them change.
@@ -144,8 +145,10 @@ static void update_thread(void)
return;
fail:
/* Critical section start */
- if(write_sigio_pid != -1)
+ if (write_sigio_pid != -1) {
os_kill_process(write_sigio_pid, 1);
+ free_stack(write_sigio_stack, 0);
+ }
write_sigio_pid = -1;
close(sigio_private[0]);
close(sigio_private[1]);
@@ -243,7 +246,6 @@ static struct pollfd *setup_initial_poll
static void write_sigio_workaround(void)
{
- unsigned long stack;
struct pollfd *p;
int err;
int l_write_sigio_fds[2];
@@ -293,7 +295,8 @@ static void write_sigio_workaround(void)
memcpy(sigio_private, l_sigio_private, sizeof(l_sigio_private));
write_sigio_pid = run_helper_thread(write_sigio_thread, NULL,
- CLONE_FILES | CLONE_VM, &stack, 0);
+ CLONE_FILES | CLONE_VM,
+ &write_sigio_stack);
if (write_sigio_pid < 0)
goto out_clear;
@@ -356,10 +359,12 @@ out:
static void sigio_cleanup(void)
{
- if(write_sigio_pid != -1){
- os_kill_process(write_sigio_pid, 1);
- write_sigio_pid = -1;
- }
+ if (write_sigio_pid == -1)
+ return;
+
+ os_kill_process(write_sigio_pid, 1);
+ free_stack(write_sigio_stack, 0);
+ write_sigio_pid = -1;
}
__uml_exitcall(sigio_cleanup);
Index: linux-2.6.21-mm/arch/um/drivers/chan_user.c
===================================================================
--- linux-2.6.21-mm.orig/arch/um/drivers/chan_user.c 2007-06-13 18:44:36.000000000 -0400
+++ linux-2.6.21-mm/arch/um/drivers/chan_user.c 2007-06-13 18:44:41.000000000 -0400
@@ -161,7 +161,7 @@ static int winch_tramp(int fd, struct tt
* problem with /dev/net/tun, which if held open by this
* thread, prevents the TUN/TAP device from being reused.
*/
- err = run_helper_thread(winch_thread, &data, CLONE_FILES, stack_out, 0);
+ err = run_helper_thread(winch_thread, &data, CLONE_FILES, stack_out);
if(err < 0){
printk("fork of winch_thread failed - errno = %d\n", -err);
goto out_close;
On Thu, 14 Jun 2007 16:26:55 -0400
Jeff Dike <[email protected]> wrote:
> --- linux-2.6.21-mm.orig/arch/um/drivers/xterm.c 2007-06-13 17:13:42.000000000 -0400
> +++ linux-2.6.21-mm/arch/um/drivers/xterm.c 2007-06-13 18:44:41.000000000 -0400
> @@ -132,7 +132,7 @@ static int xterm_open(int input, int out
> }
>
> sprintf(title, data->title, data->device);
> - pid = run_helper(NULL, NULL, argv, NULL);
> + pid = run_helper(NULL, NULL, argv);
> if (pid < 0) {
> err = pid;
> printk(UM_KERN_ERR "xterm_open : run_helper failed, "
Something's gone wrong here. My copy of this file has
pid = run_helper(NULL, NULL, argv, &stack);
On Tue, Jun 26, 2007 at 01:35:50PM -0700, Andrew Morton wrote:
> > sprintf(title, data->title, data->device);
> > - pid = run_helper(NULL, NULL, argv, NULL);
> > + pid = run_helper(NULL, NULL, argv);
> > if (pid < 0) {
> > err = pid;
> > printk(UM_KERN_ERR "xterm_open : run_helper failed, "
>
> Something's gone wrong here. My copy of this file has
>
> pid = run_helper(NULL, NULL, argv, &stack);
Looks like you're applying patches out of order. This is from the
14th, while a patch from the 13th ("UML - xterm driver tidying") has
- pid = run_helper(NULL, NULL, argv, &stack);
...
+ pid = run_helper(NULL, NULL, argv, NULL);
If you don't want to fiddle with this, just drop it and I'll rediff
against the next -mm and resend.
Jeff
--
Work email - jdike at linux dot intel dot com
On Tue, 26 Jun 2007 17:53:28 -0400
Jeff Dike <[email protected]> wrote:
> On Tue, Jun 26, 2007 at 01:35:50PM -0700, Andrew Morton wrote:
> > > sprintf(title, data->title, data->device);
> > > - pid = run_helper(NULL, NULL, argv, NULL);
> > > + pid = run_helper(NULL, NULL, argv);
> > > if (pid < 0) {
> > > err = pid;
> > > printk(UM_KERN_ERR "xterm_open : run_helper failed, "
> >
> > Something's gone wrong here. My copy of this file has
> >
> > pid = run_helper(NULL, NULL, argv, &stack);
>
> Looks like you're applying patches out of order.
Yes, I am. After a few days off and a few more days being lazy I have
600-odd patches (and followups thereto) to process.
- If I do them in-order, I merge stuff which is out of date or wrong
- If I do them in reverse-order, I can miss dependencies.
On balance, reverse-order seems to be better.
> This is from the
> 14th, while a patch from the 13th ("UML - xterm driver tidying") has
> - pid = run_helper(NULL, NULL, argv, &stack);
> ...
> + pid = run_helper(NULL, NULL, argv, NULL);
>
> If you don't want to fiddle with this, just drop it and I'll rediff
> against the next -mm and resend.
I sorted it out, thanks.
So I'm running the generic version of this on i386 with 8k stacks (below),
with a quick LTP run.
Holy cow, either we use a _lot_ of stack or these numbers are off:
vmm:/home/akpm> dmesg -s 1000000|grep 'bytes left'
khelper used greatest stack depth: 7176 bytes left
khelper used greatest stack depth: 7064 bytes left
khelper used greatest stack depth: 6840 bytes left
khelper used greatest stack depth: 6812 bytes left
hostname used greatest stack depth: 6636 bytes left
uname used greatest stack depth: 6592 bytes left
uname used greatest stack depth: 6284 bytes left
hotplug used greatest stack depth: 5568 bytes left
rpc.nfsd used greatest stack depth: 5136 bytes left
chown02 used greatest stack depth: 4956 bytes left
fchown01 used greatest stack depth: 4892 bytes left
That's the sum of process stack and interrupt stack, but I doubt if this
little box is using much interrupt stack space.
No wonder people are still getting stack overflows with 4k stacks...
From: Jeff Dike <[email protected]>
Add generic exit-time stack-depth checking to CONFIG_DEBUG_STACK_USAGE.
This also adds UML support.
Tested on UML and i386.
[[email protected]: cleanups, speedups, tweaks]
Signed-off-by: Jeff Dike <[email protected]>
Cc: Oleg Nesterov <[email protected]>
Cc: Ingo Molnar <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
---
arch/um/Kconfig.debug | 9 +++++++++
arch/um/defconfig | 1 +
include/asm-um/thread_info.h | 9 +++++++++
kernel/exit.c | 29 +++++++++++++++++++++++++++++
4 files changed, 48 insertions(+)
diff -puN arch/um/Kconfig.debug~add-generic-exit-time-stack-depth-checking-to-config_debug_stack_usage arch/um/Kconfig.debug
--- a/arch/um/Kconfig.debug~add-generic-exit-time-stack-depth-checking-to-config_debug_stack_usage
+++ a/arch/um/Kconfig.debug
@@ -47,4 +47,13 @@ config GCOV
If you're involved in UML kernel development and want to use gcov,
say Y. If you're unsure, say N.
+config DEBUG_STACK_USAGE
+ bool "Stack utilization instrumentation"
+ default N
+ help
+ Track the maximum kernel stack usage - this will look at each
+ kernel stack at process exit and log it if it's the deepest
+ stack seen so far.
+
+ This option will slow down process creation and destruction somewhat.
endmenu
diff -puN arch/um/defconfig~add-generic-exit-time-stack-depth-checking-to-config_debug_stack_usage arch/um/defconfig
--- a/arch/um/defconfig~add-generic-exit-time-stack-depth-checking-to-config_debug_stack_usage
+++ a/arch/um/defconfig
@@ -527,3 +527,4 @@ CONFIG_FORCED_INLINING=y
# CONFIG_RCU_TORTURE_TEST is not set
# CONFIG_GPROF is not set
# CONFIG_GCOV is not set
+# CONFIG_DEBUG_STACK_USAGE is not set
diff -puN include/asm-um/thread_info.h~add-generic-exit-time-stack-depth-checking-to-config_debug_stack_usage include/asm-um/thread_info.h
--- a/include/asm-um/thread_info.h~add-generic-exit-time-stack-depth-checking-to-config_debug_stack_usage
+++ a/include/asm-um/thread_info.h
@@ -52,10 +52,19 @@ static inline struct thread_info *curren
return ti;
}
+#ifdef CONFIG_DEBUG_STACK_USAGE
+
+#define alloc_thread_info(tsk) \
+ ((struct thread_info *) __get_free_pages(GFP_KERNEL | __GFP_ZERO, \
+ CONFIG_KERNEL_STACK_ORDER))
+#else
+
/* thread information allocation */
#define alloc_thread_info(tsk) \
((struct thread_info *) __get_free_pages(GFP_KERNEL, \
CONFIG_KERNEL_STACK_ORDER))
+#endif
+
#define free_thread_info(ti) \
free_pages((unsigned long)(ti),CONFIG_KERNEL_STACK_ORDER)
diff -puN kernel/exit.c~add-generic-exit-time-stack-depth-checking-to-config_debug_stack_usage kernel/exit.c
--- a/kernel/exit.c~add-generic-exit-time-stack-depth-checking-to-config_debug_stack_usage
+++ a/kernel/exit.c
@@ -868,6 +868,34 @@ static void exit_notify(struct task_stru
release_task(tsk);
}
+#ifdef CONFIG_DEBUG_STACK_USAGE
+static void check_stack_usage(void)
+{
+ static DEFINE_SPINLOCK(low_water_lock);
+ static int lowest_to_date = THREAD_SIZE;
+ unsigned long *n = end_of_stack(current);
+ unsigned long free;
+
+ while (*n == 0)
+ n++;
+ free = (unsigned long)n - (unsigned long)end_of_stack(current);
+
+ if (free >= lowest_to_date)
+ return;
+
+ spin_lock(&low_water_lock);
+ if (free < lowest_to_date) {
+ printk(KERN_WARNING "%s used greatest stack depth: %lu bytes "
+ "left\n",
+ current->comm, free);
+ lowest_to_date = free;
+ }
+ spin_unlock(&low_water_lock);
+}
+#else
+static inline void check_stack_usage(void) {}
+#endif
+
fastcall NORET_TYPE void do_exit(long code)
{
struct task_struct *tsk = current;
@@ -959,6 +987,7 @@ fastcall NORET_TYPE void do_exit(long co
exit_sem(tsk);
__exit_files(tsk);
__exit_fs(tsk);
+ check_stack_usage();
exit_thread();
cpuset_exit(tsk);
exit_keys(tsk);
_
Il Wed, Jun 27, 2007 at 11:37:01PM -0700, Andrew Morton ha scritto:
>
> So I'm running the generic version of this on i386 with 8k stacks (below),
> with a quick LTP run.
>
> Holy cow, either we use a _lot_ of stack or these numbers are off:
>
> vmm:/home/akpm> dmesg -s 1000000|grep 'bytes left'
> khelper used greatest stack depth: 7176 bytes left
> khelper used greatest stack depth: 7064 bytes left
> khelper used greatest stack depth: 6840 bytes left
> khelper used greatest stack depth: 6812 bytes left
> hostname used greatest stack depth: 6636 bytes left
> uname used greatest stack depth: 6592 bytes left
> uname used greatest stack depth: 6284 bytes left
> hotplug used greatest stack depth: 5568 bytes left
> rpc.nfsd used greatest stack depth: 5136 bytes left
> chown02 used greatest stack depth: 4956 bytes left
> fchown01 used greatest stack depth: 4892 bytes left
>
> That's the sum of process stack and interrupt stack, but I doubt if this
> little box is using much interrupt stack space.
>
> No wonder people are still getting stack overflows with 4k stacks...
Hi Andrew,
I was a bit worried about stack usage on my setup and google found your
mail :P
FYI:
khelper used greatest stack depth: 3228 bytes left
khelper used greatest stack depth: 3124 bytes left
busybox used greatest stack depth: 2808 bytes left
modprobe used greatest stack depth: 2744 bytes left
busybox used greatest stack depth: 2644 bytes left
modprobe used greatest stack depth: 1836 bytes left
modprobe used greatest stack depth: 1176 bytes left
java used greatest stack depth: 932 bytes left
java used greatest stack depth: 540 bytes left
I'm running git-current, with 4KiB stacks; filesystems are ext3 and XFS
on LVM (on libata devices).
Does it make sense to raise STACK_WARN to get a stack trace in do_IRQ?
Or is 540 bytes still "safe" taking into account the separate IRQ stack?
Luca
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On Sun, 5 Aug 2007 22:41:14 +0200 Luca Tettamanti <[email protected]> wrote:
> Il Wed, Jun 27, 2007 at 11:37:01PM -0700, Andrew Morton ha scritto:
> >
> > So I'm running the generic version of this on i386 with 8k stacks (below),
> > with a quick LTP run.
> >
> > Holy cow, either we use a _lot_ of stack or these numbers are off:
> >
> > vmm:/home/akpm> dmesg -s 1000000|grep 'bytes left'
> > khelper used greatest stack depth: 7176 bytes left
> > khelper used greatest stack depth: 7064 bytes left
> > khelper used greatest stack depth: 6840 bytes left
> > khelper used greatest stack depth: 6812 bytes left
> > hostname used greatest stack depth: 6636 bytes left
> > uname used greatest stack depth: 6592 bytes left
> > uname used greatest stack depth: 6284 bytes left
> > hotplug used greatest stack depth: 5568 bytes left
> > rpc.nfsd used greatest stack depth: 5136 bytes left
> > chown02 used greatest stack depth: 4956 bytes left
> > fchown01 used greatest stack depth: 4892 bytes left
> >
> > That's the sum of process stack and interrupt stack, but I doubt if this
> > little box is using much interrupt stack space.
> >
> > No wonder people are still getting stack overflows with 4k stacks...
>
> Hi Andrew,
> I was a bit worried about stack usage on my setup and google found your
> mail :P
>
> FYI:
>
> khelper used greatest stack depth: 3228 bytes left
> khelper used greatest stack depth: 3124 bytes left
> busybox used greatest stack depth: 2808 bytes left
> modprobe used greatest stack depth: 2744 bytes left
> busybox used greatest stack depth: 2644 bytes left
> modprobe used greatest stack depth: 1836 bytes left
> modprobe used greatest stack depth: 1176 bytes left
> java used greatest stack depth: 932 bytes left
> java used greatest stack depth: 540 bytes left
>
> I'm running git-current, with 4KiB stacks; filesystems are ext3 and XFS
> on LVM (on libata devices).
> Does it make sense to raise STACK_WARN to get a stack trace in do_IRQ?
> Or is 540 bytes still "safe" taking into account the separate IRQ stack?
>
540 bytes free means that we've used 90% of the stack. I'd say it is
extremely unsafe.
Unbelieveably unsafe. I'm suspecting that the instrumentation is lying to
us for some reason.