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| author | Michal Hocko <mhocko@suse.com> | 2017-04-19 09:52:46 +0200 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2017-04-19 15:53:48 -0700 |
| commit | 80d136e138f59de35aafb0440e8ab2f51c40ccd5 (patch) | |
| tree | 1428d44edff582ddc68e9a8676f3fcf064ed60a1 /mm/vmstat.c | |
| parent | c4bac97b0d3405f760c30636ff0b2e32810507d3 (diff) | |
| download | lwn-80d136e138f59de35aafb0440e8ab2f51c40ccd5.tar.gz lwn-80d136e138f59de35aafb0440e8ab2f51c40ccd5.zip | |
mm: make mm_percpu_wq non freezable
Geert has reported a freeze during PM resume and some additional
debugging has shown that the device_resume worker cannot make a forward
progress because it waits for an event which is stuck waiting in
drain_all_pages:
INFO: task kworker/u4:0:5 blocked for more than 120 seconds.
Not tainted 4.11.0-rc7-koelsch-00029-g005882e53d62f25d-dirty #3476
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
kworker/u4:0 D 0 5 2 0x00000000
Workqueue: events_unbound async_run_entry_fn
__schedule
schedule
schedule_timeout
wait_for_common
dpm_wait_for_superior
device_resume
async_resume
async_run_entry_fn
process_one_work
worker_thread
kthread
[...]
bash D 0 1703 1694 0x00000000
__schedule
schedule
schedule_timeout
wait_for_common
flush_work
drain_all_pages
start_isolate_page_range
alloc_contig_range
cma_alloc
__alloc_from_contiguous
cma_allocator_alloc
__dma_alloc
arm_dma_alloc
sh_eth_ring_init
sh_eth_open
sh_eth_resume
dpm_run_callback
device_resume
dpm_resume
dpm_resume_end
suspend_devices_and_enter
pm_suspend
state_store
kernfs_fop_write
__vfs_write
vfs_write
SyS_write
[...]
Showing busy workqueues and worker pools:
[...]
workqueue mm_percpu_wq: flags=0xc
pwq 2: cpus=1 node=0 flags=0x0 nice=0 active=0/0
delayed: drain_local_pages_wq, vmstat_update
pwq 0: cpus=0 node=0 flags=0x0 nice=0 active=0/0
delayed: drain_local_pages_wq BAR(1703), vmstat_update
Tetsuo has properly noted that mm_percpu_wq is created as WQ_FREEZABLE
so it is frozen this early during resume so we are effectively
deadlocked. Fix this by dropping WQ_FREEZABLE when creating
mm_percpu_wq. We really want to have it operational all the time.
Fixes: ce612879ddc7 ("mm: move pcp and lru-pcp draining into single wq")
Reported-and-tested-by: Geert Uytterhoeven <geert@linux-m68k.org>
Debugged-by: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Signed-off-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/vmstat.c')
| -rw-r--r-- | mm/vmstat.c | 3 |
1 files changed, 1 insertions, 2 deletions
diff --git a/mm/vmstat.c b/mm/vmstat.c index 809025ed97ea..5a4f5c5a31e8 100644 --- a/mm/vmstat.c +++ b/mm/vmstat.c @@ -1768,8 +1768,7 @@ void __init init_mm_internals(void) { int ret __maybe_unused; - mm_percpu_wq = alloc_workqueue("mm_percpu_wq", - WQ_FREEZABLE|WQ_MEM_RECLAIM, 0); + mm_percpu_wq = alloc_workqueue("mm_percpu_wq", WQ_MEM_RECLAIM, 0); #ifdef CONFIG_SMP ret = cpuhp_setup_state_nocalls(CPUHP_MM_VMSTAT_DEAD, "mm/vmstat:dead", |