Re: [PATCH] mm,page_alloc: PF_WQ_WORKER threads must sleep at should_reclaim_retry().

From: Tetsuo Handa
Date: Tue Aug 21 2018 - 17:07:55 EST


On 2018/08/03 15:16, Michal Hocko wrote:
> On Fri 03-08-18 07:05:54, Tetsuo Handa wrote:
>> On 2018/07/31 14:09, Michal Hocko wrote:
>>> On Tue 31-07-18 06:01:48, Tetsuo Handa wrote:
>>>> On 2018/07/31 4:10, Michal Hocko wrote:
>>>>> Since should_reclaim_retry() should be a natural reschedule point,
>>>>> let's do the short sleep for PF_WQ_WORKER threads unconditionally in
>>>>> order to guarantee that other pending work items are started. This will
>>>>> workaround this problem and it is less fragile than hunting down when
>>>>> the sleep is missed. E.g. we used to have a sleeping point in the oom
>>>>> path but this has been removed recently because it caused other issues.
>>>>> Having a single sleeping point is more robust.
>>>>
>>>> linux.git has not removed the sleeping point in the OOM path yet. Since removing the
>>>> sleeping point in the OOM path can mitigate CVE-2016-10723, please do so immediately.
>>>
>>> is this an {Acked,Reviewed,Tested}-by?
>>>
>>> I will send the patch to Andrew if the patch is ok.
>>>
>>>> (And that change will conflict with Roman's cgroup aware OOM killer patchset. But it
>>>> should be easy to rebase.)
>>>
>>> That is still a WIP so I would lose sleep over it.
>>>
>>
>> Now that Roman's cgroup aware OOM killer patchset will be dropped from linux-next.git ,
>> linux-next.git will get the sleeping point removed. Please send this patch to linux-next.git .
>
> I still haven't heard any explicit confirmation that the patch works for
> your workload. Should I beg for it? Or you simply do not want to have
> your stamp on the patch? If yes, I can live with that but this playing
> hide and catch is not really a lot of fun.
>

I noticed that the patch has not been sent to linux-next.git yet.
Please send to linux-next.git without my stamp on the patch.

[ 44.863590] Out of memory: Kill process 1071 (a.out) score 865 or sacrifice child
[ 44.867666] Killed process 1817 (a.out) total-vm:5244kB, anon-rss:1040kB, file-rss:0kB, shmem-rss:0kB
[ 44.872176] oom_reaper: reaped process 1817 (a.out), now anon-rss:0kB, file-rss:0kB, shmem-rss:0kB
[ 91.698761] BUG: workqueue lockup - pool cpus=0 node=0 flags=0x0 nice=0 stuck for 48s!
[ 91.702313] Showing busy workqueues and worker pools:
[ 91.705011] workqueue events: flags=0x0
[ 91.707482] pwq 0: cpus=0 node=0 flags=0x0 nice=0 active=8/256
[ 91.710524] pending: vmpressure_work_fn, vmw_fb_dirty_flush [vmwgfx], e1000_watchdog [e1000], vmstat_shepherd, free_work, mmdrop_async_fn, mmdrop_async_fn, check_corruption
[ 91.717439] workqueue events_freezable: flags=0x4
[ 91.720161] pwq 0: cpus=0 node=0 flags=0x0 nice=0 active=1/256
[ 91.723304] pending: vmballoon_work [vmw_balloon]
[ 91.726167] workqueue events_power_efficient: flags=0x80
[ 91.729139] pwq 0: cpus=0 node=0 flags=0x0 nice=0 active=4/256
[ 91.732253] pending: fb_flashcursor, gc_worker [nf_conntrack], neigh_periodic_work, neigh_periodic_work
[ 91.736471] workqueue events_freezable_power_: flags=0x84
[ 91.739546] pwq 0: cpus=0 node=0 flags=0x0 nice=0 active=1/256
[ 91.742696] in-flight: 2097:disk_events_workfn
[ 91.745517] workqueue mm_percpu_wq: flags=0x8
[ 91.748069] pwq 0: cpus=0 node=0 flags=0x0 nice=0 active=2/256
[ 91.751182] pending: drain_local_pages_wq BAR(1830), vmstat_update
[ 91.754661] workqueue mpt_poll_0: flags=0x8
[ 91.757161] pwq 0: cpus=0 node=0 flags=0x0 nice=0 active=1/256
[ 91.759958] pending: mpt_fault_reset_work [mptbase]
[ 91.762696] workqueue xfs-data/sda1: flags=0xc
[ 91.765353] pwq 0: cpus=0 node=0 flags=0x0 nice=0 active=3/256
[ 91.768248] pending: xfs_end_io [xfs], xfs_end_io [xfs], xfs_end_io [xfs]
[ 91.771589] workqueue xfs-cil/sda1: flags=0xc
[ 91.774009] pwq 0: cpus=0 node=0 flags=0x0 nice=0 active=1/256
[ 91.776800] pending: xlog_cil_push_work [xfs] BAR(703)
[ 91.779464] workqueue xfs-reclaim/sda1: flags=0xc
[ 91.782017] pwq 0: cpus=0 node=0 flags=0x0 nice=0 active=1/256
[ 91.784599] pending: xfs_reclaim_worker [xfs]
[ 91.786930] workqueue xfs-sync/sda1: flags=0x4
[ 91.789289] pwq 0: cpus=0 node=0 flags=0x0 nice=0 active=1/256
[ 91.792075] pending: xfs_log_worker [xfs]
[ 91.794213] pool 0: cpus=0 node=0 flags=0x0 nice=0 hung=48s workers=4 idle: 52 13 5
[ 121.906640] BUG: workqueue lockup - pool cpus=0 node=0 flags=0x0 nice=0 stuck for 78s!
[ 121.909572] Showing busy workqueues and worker pools:
[ 121.911703] workqueue events: flags=0x0
[ 121.913531] pwq 0: cpus=0 node=0 flags=0x0 nice=0 active=8/256
[ 121.915873] pending: vmpressure_work_fn, vmw_fb_dirty_flush [vmwgfx], e1000_watchdog [e1000], vmstat_shepherd, free_work, mmdrop_async_fn, mmdrop_async_fn, check_corruption
[ 121.921962] workqueue events_freezable: flags=0x4
[ 121.924336] pwq 0: cpus=0 node=0 flags=0x0 nice=0 active=1/256
[ 121.926941] pending: vmballoon_work [vmw_balloon]
[ 121.929226] workqueue events_power_efficient: flags=0x80
[ 121.931554] pwq 0: cpus=0 node=0 flags=0x0 nice=0 active=4/256
[ 121.933983] pending: fb_flashcursor, gc_worker [nf_conntrack], neigh_periodic_work, neigh_periodic_work
[ 121.937415] workqueue events_freezable_power_: flags=0x84
[ 121.939719] pwq 0: cpus=0 node=0 flags=0x0 nice=0 active=1/256
[ 121.942166] in-flight: 2097:disk_events_workfn
[ 121.944385] workqueue mm_percpu_wq: flags=0x8
[ 121.946468] pwq 0: cpus=0 node=0 flags=0x0 nice=0 active=2/256
[ 121.948975] pending: drain_local_pages_wq BAR(1830), vmstat_update
[ 121.951808] workqueue mpt_poll_0: flags=0x8
[ 121.953864] pwq 0: cpus=0 node=0 flags=0x0 nice=0 active=1/256
[ 121.956245] pending: mpt_fault_reset_work [mptbase]
[ 121.958505] workqueue xfs-data/sda1: flags=0xc
[ 121.960514] pwq 0: cpus=0 node=0 flags=0x0 nice=0 active=3/256
[ 121.962896] pending: xfs_end_io [xfs], xfs_end_io [xfs], xfs_end_io [xfs]
[ 121.965682] workqueue xfs-cil/sda1: flags=0xc
[ 121.967639] pwq 0: cpus=0 node=0 flags=0x0 nice=0 active=1/256
[ 121.970004] pending: xlog_cil_push_work [xfs] BAR(703)
[ 121.972285] workqueue xfs-reclaim/sda1: flags=0xc
[ 121.974339] pwq 0: cpus=0 node=0 flags=0x0 nice=0 active=1/256
[ 121.976779] pending: xfs_reclaim_worker [xfs]
[ 121.978926] workqueue xfs-sync/sda1: flags=0x4
[ 121.980997] pwq 0: cpus=0 node=0 flags=0x0 nice=0 active=1/256
[ 121.983364] pending: xfs_log_worker [xfs]
[ 121.985326] pool 0: cpus=0 node=0 flags=0x0 nice=0 hung=78s workers=4 idle: 52 13 5
[ 147.872620] sysrq: SysRq : Terminate All Tasks