Some kernel threads are always in D state, when we enable hung_task,
it will misjudge, we should skip these to narrow the scope.
exp mtk mobilephone:
root 435 435 2 0 0 mtk_lpm_monitor_thread 0 D LPM-0
root 436 436 2 0 0 mtk_lpm_monitor_thread 0 D LPM-1
root 437 437 2 0 0 mtk_lpm_monitor_thread 0 D LPM-2
root 438 438 2 0 0 mtk_lpm_monitor_thread 0 D LPM-3
root 439 439 2 0 0 mtk_lpm_monitor_thread 0 D LPM-4
root 440 440 2 0 0 mtk_lpm_monitor_thread 0 D LPM-5
root 441 441 2 0 0 mtk_lpm_monitor_thread 0 D LPM-6
root 442 442 2 0 0 mtk_lpm_monitor_thread 0 D LPM-7
Signed-off-by: chenguanyou <[email protected]>
---
Documentation/admin-guide/sysctl/kernel.rst | 16 ++++++++++++
include/linux/sched/sysctl.h | 4 +++
kernel/hung_task.c | 17 +++++++++++++
kernel/sysctl.c | 16 ++++++++++++
lib/Kconfig.debug | 27 +++++++++++++++++++++
5 files changed, 80 insertions(+)
diff --git a/Documentation/admin-guide/sysctl/kernel.rst b/Documentation/admin-guide/sysctl/kernel.rst
index 1d56a6b73a4e..081ca22db4d5 100644
--- a/Documentation/admin-guide/sysctl/kernel.rst
+++ b/Documentation/admin-guide/sysctl/kernel.rst
@@ -405,6 +405,22 @@ This file shows up if ``CONFIG_DETECT_HUNG_TASK`` is enabled.
-1: report an infinite number of warnings.
+hung_task_filter_kthread
+========================
+
+We should skip kthread when a hung task is detected.
+This file shows up if ``CONFIG_DEFAULT_HUNG_TASK_FILTER_KTHREAD`` is enabled.
+
+= =========================================================
+0 Not skip detect kthread.
+1 Skip detect kthread.
+= =========================================================
+
+hung_task_check_comm
+====================
+
+We should skip non ``hung_task_check_comm`` when a hung task is detected.
+This file shows up if ``CONFIG_DEFAULT_HUNG_TASK_CHECK_COMM`` is enabled.
hyperv_record_panic_msg
=======================
diff --git a/include/linux/sched/sysctl.h b/include/linux/sched/sysctl.h
index 3c31ba88aca5..e8a9a28215bf 100644
--- a/include/linux/sched/sysctl.h
+++ b/include/linux/sched/sysctl.h
@@ -14,11 +14,15 @@ extern unsigned int sysctl_hung_task_all_cpu_backtrace;
#define sysctl_hung_task_all_cpu_backtrace 0
#endif /* CONFIG_SMP */
+#define TASK_COMM_LEN 16
+
extern int sysctl_hung_task_check_count;
extern unsigned int sysctl_hung_task_panic;
extern unsigned long sysctl_hung_task_timeout_secs;
extern unsigned long sysctl_hung_task_check_interval_secs;
extern int sysctl_hung_task_warnings;
+extern unsigned int sysctl_hung_task_filter_kthread;
+extern char sysctl_hung_task_check_comm[TASK_COMM_LEN];
int proc_dohung_task_timeout_secs(struct ctl_table *table, int write,
void *buffer, size_t *lenp, loff_t *ppos);
#else
diff --git a/kernel/hung_task.c b/kernel/hung_task.c
index 396ebaebea3f..baee8466b902 100644
--- a/kernel/hung_task.c
+++ b/kernel/hung_task.c
@@ -23,6 +23,7 @@
#include <linux/sched/sysctl.h>
#include <trace/events/sched.h>
+#include <linux/string.h>
/*
* The number of tasks checked:
@@ -48,6 +49,16 @@ unsigned long __read_mostly sysctl_hung_task_timeout_secs = CONFIG_DEFAULT_HUNG_
*/
unsigned long __read_mostly sysctl_hung_task_check_interval_secs;
+/*
+ * Non-zero means no checking kthread
+ */
+unsigned int __read_mostly sysctl_hung_task_filter_kthread = CONFIG_DEFAULT_HUNG_TASK_FILTER_KTHREAD;
+
+/*
+ * Only one
+ */
+char __read_mostly sysctl_hung_task_check_comm[TASK_COMM_LEN] = CONFIG_DEFAULT_HUNG_TASK_CHECK_COMM;
+
int __read_mostly sysctl_hung_task_warnings = 10;
static int __read_mostly did_panic;
@@ -88,6 +99,12 @@ static void check_hung_task(struct task_struct *t, unsigned long timeout)
{
unsigned long switch_count = t->nvcsw + t->nivcsw;
+ if (unlikely(strlen(sysctl_hung_task_check_comm) && !strstr(t->comm, sysctl_hung_task_check_comm)))
+ return;
+
+ if (unlikely(sysctl_hung_task_filter_kthread && t->flags & PF_KTHREAD))
+ return;
+
/*
* Ensure the task is not frozen.
* Also, skip vfork and any other user process that freezer should skip.
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 62fbd09b5dc1..1daede87c88d 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -2519,6 +2519,22 @@ static struct ctl_table kern_table[] = {
.proc_handler = proc_dointvec_minmax,
.extra1 = &neg_one,
},
+ {
+ .procname = "hung_task_filter_kthread",
+ .data = &sysctl_hung_task_filter_kthread,
+ .maxlen = sizeof(int),
+ .mode = 0644,
+ .proc_handler = proc_dointvec_minmax,
+ .extra1 = SYSCTL_ZERO,
+ .extra2 = SYSCTL_ONE,
+ },
+ {
+ .procname = "hung_task_check_comm",
+ .data = &sysctl_hung_task_check_comm,
+ .maxlen = TASK_COMM_LEN,
+ .mode = 0644,
+ .proc_handler = proc_dostring,
+ },
#endif
#ifdef CONFIG_RT_MUTEXES
{
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 2c7f46b366f1..63570b1fec35 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -1101,6 +1101,33 @@ config DEFAULT_HUNG_TASK_TIMEOUT
A timeout of 0 disables the check. The default is two minutes.
Keeping the default should be fine in most cases.
+config DEFAULT_HUNG_TASK_FILTER_KTHREAD
+ int "Default filter kthread for hung task"
+ depends on DETECT_HUNG_TASK
+ range 0 1
+ default 0
+ help
+ This option controls filter kthread uses to determine when
+ a kernel task has become "state=TASK_UNINTERRUPTIBLE" and should be skipped.
+
+ It can be adjusted at runtime via the kernel.hung_task_filter_kthread
+ sysctl or by writing a value to
+ /proc/sys/kernel/hung_task_filter_kthread.
+
+ A filter of 1 disables the check.
+
+config DEFAULT_HUNG_TASK_CHECK_COMM
+ string "Default check only one comm"
+ depends on DETECT_HUNG_TASK
+ default ""
+ help
+ This option controls only detect "task.comm = kernel.hung_task_check_comm" when
+ it become "state=TASK_UNINTERRUPTIBLE", skip other threads.
+
+ It can be adjusted at runtime via the kernel.hung_task_check_comm
+ sysctl or by writing a value to
+ /proc/sys/kernel/hung_task_check_comm.
+
config BOOTPARAM_HUNG_TASK_PANIC
bool "Panic (Reboot) On Hung Tasks"
depends on DETECT_HUNG_TASK
--
2.17.1
On Fri 21-05-21 14:38:06, 陈冠有 wrote:
> when we no skip kthread, exp log:
> 3,25164,832483138,-; (1)[67:khungtaskd]INFO: task amms_task:51 blocked for
> more than 120 seconds.
> 3,25165,832483169,-; (1)[67:khungtaskd] Tainted: P S W O
> 4.14.186-g9d5f2ff-dirty #4
> 3,25166,832483186,-; (1)[67:khungtaskd]"echo 0 >
> /proc/sys/kernel/hung_task_timeout_secs" disables this message.
> 6,25167,832483205,-; (1)[67:khungtaskd]amms_task D 0 51 2
> 0x00000000
> 4,25168,832483232,-; (1)[67:khungtaskd]Call trace:
> 4,25169,832483268,-; (1)[67:khungtaskd] __switch_to+0x134/0x150
> 4,25170,832483297,-; (1)[67:khungtaskd] __schedule+0xd5c/0x1100
> 4,25171,832483318,-; (1)[67:khungtaskd] schedule+0x70/0x90
> 4,25172,832483343,-; (1)[67:khungtaskd] kthread+0xfc/0x18c
> 4,25173,832483365,-; (1)[67:khungtaskd] ret_from_fork+0x10/0x18
> 3,25174,832483482,-; (1)[67:khungtaskd]INFO: task mdrt_thread:123 blocked
> for more than 120 seconds.
> 3,25175,832483501,-; (1)[67:khungtaskd] Tainted: P S W O
> 4.14.186-g9d5f2ff-dirty #4
> 3,25176,832483516,-; (1)[67:khungtaskd]"echo 0 >
> /proc/sys/kernel/hung_task_timeout_secs" disables this message.
> 6,25177,832483533,-; (1)[67:khungtaskd]mdrt_thread D 0 123 2
> 0x00000000
> 4,25178,832483555,-; (1)[67:khungtaskd]Call trace:
> 4,25179,832483574,-; (1)[67:khungtaskd] __switch_to+0x134/0x150
> 4,25180,832483595,-; (1)[67:khungtaskd] __schedule+0xd5c/0x1100
> 4,25181,832483615,-; (1)[67:khungtaskd] schedule+0x70/0x90
> 4,25182,832483635,-; (1)[67:khungtaskd] kthread+0xfc/0x18c
> 4,25183,832483655,-; (1)[67:khungtaskd] ret_from_fork+0x10/0x18
> 3,25184,832483737,-; (1)[67:khungtaskd]INFO: task scp_power_reset:227
> blocked for more than 120 seconds.
What are all these kernel threads doing and why it is ok to inhibit them
in the report.
--
Michal Hocko
SUSE Labs
On Fri, 21 May 2021 21:25:44 +0800 chenguanyou <[email protected]> wrote:
> Some kernel threads are always in D state, when we enable hung_task,
> it will misjudge, we should skip these to narrow the scope.
>
> exp mtk mobilephone:
> root 435 435 2 0 0 mtk_lpm_monitor_thread 0 D LPM-0
> root 436 436 2 0 0 mtk_lpm_monitor_thread 0 D LPM-1
> root 437 437 2 0 0 mtk_lpm_monitor_thread 0 D LPM-2
> root 438 438 2 0 0 mtk_lpm_monitor_thread 0 D LPM-3
> root 439 439 2 0 0 mtk_lpm_monitor_thread 0 D LPM-4
> root 440 440 2 0 0 mtk_lpm_monitor_thread 0 D LPM-5
> root 441 441 2 0 0 mtk_lpm_monitor_thread 0 D LPM-6
> root 442 442 2 0 0 mtk_lpm_monitor_thread 0 D LPM-7
Maybe convert these threads to use TASK_IDLE?