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authorMichal Hocko <mhocko@suse.com>2017-04-19 09:52:46 +0200
committerLinus Torvalds <torvalds@linux-foundation.org>2017-04-19 15:53:48 -0700
commit80d136e138f59de35aafb0440e8ab2f51c40ccd5 (patch)
parentc4bac97b0d3405f760c30636ff0b2e32810507d3 (diff)
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>
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",
+ mm_percpu_wq = alloc_workqueue("mm_percpu_wq", WQ_MEM_RECLAIM, 0);
ret = cpuhp_setup_state_nocalls(CPUHP_MM_VMSTAT_DEAD, "mm/vmstat:dead",