diff options
| author | Tejun Heo <tj@kernel.org> | 2015-12-08 11:28:04 -0500 |
|---|---|---|
| committer | Tejun Heo <tj@kernel.org> | 2015-12-08 11:29:47 -0500 |
| commit | 82607adcf9cdf40fb7b5331269780c8f70ec6e35 (patch) | |
| tree | 22c7849ef8e873007dd56a63b109937046d897db /lib | |
| parent | 03e0d4610bf4d4a93bfa16b2474ed4fd5243aa71 (diff) | |
workqueue: implement lockup detector
Workqueue stalls can happen from a variety of usage bugs such as
missing WQ_MEM_RECLAIM flag or concurrency managed work item
indefinitely staying RUNNING. These stalls can be extremely difficult
to hunt down because the usual warning mechanisms can't detect
workqueue stalls and the internal state is pretty opaque.
To alleviate the situation, this patch implements workqueue lockup
detector. It periodically monitors all worker_pools periodically and,
if any pool failed to make forward progress longer than the threshold
duration, triggers warning and dumps workqueue state as follows.
BUG: workqueue lockup - pool cpus=0 node=0 flags=0x0 nice=0 stuck for 31s!
Showing busy workqueues and worker pools:
workqueue events: flags=0x0
pwq 0: cpus=0 node=0 flags=0x0 nice=0 active=17/256
pending: monkey_wrench_fn, e1000_watchdog, cache_reap, vmstat_shepherd, release_one_tty, release_one_tty, release_one_tty, release_one_tty, release_one_tty, release_one_tty, release_one_tty, release_one_tty, release_one_tty, release_one_tty, release_one_tty, release_one_tty, cgroup_release_agent
workqueue events_power_efficient: flags=0x80
pwq 0: cpus=0 node=0 flags=0x0 nice=0 active=2/256
pending: check_lifetime, neigh_periodic_work
workqueue cgroup_pidlist_destroy: flags=0x0
pwq 0: cpus=0 node=0 flags=0x0 nice=0 active=1/1
pending: cgroup_pidlist_destroy_work_fn
...
The detection mechanism is controller through kernel parameter
workqueue.watchdog_thresh and can be updated at runtime through the
sysfs module parameter file.
v2: Decoupled from softlockup control knobs.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Don Zickus <dzickus@redhat.com>
Cc: Ulrich Obergfell <uobergfe@redhat.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Chris Mason <clm@fb.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/Kconfig.debug | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index 8c15b29d5adc..3048bf5b729a 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -812,6 +812,17 @@ config BOOTPARAM_HUNG_TASK_PANIC_VALUE default 0 if !BOOTPARAM_HUNG_TASK_PANIC default 1 if BOOTPARAM_HUNG_TASK_PANIC +config WQ_WATCHDOG + bool "Detect Workqueue Stalls" + depends on DEBUG_KERNEL + help + Say Y here to enable stall detection on workqueues. If a + worker pool doesn't make forward progress on a pending work + item for over a given amount of time, 30s by default, a + warning message is printed along with dump of workqueue + state. This can be configured through kernel parameter + "workqueue.watchdog_thresh" and its sysfs counterpart. + endmenu # "Debug lockups and hangs" config PANIC_ON_OOPS |