On Thu 22-03-18 19:46:36, Tetsuo Handa wrote: > >From b141cdbe0db852549c94d5b1e6a9967ca69d59fd Mon Sep 17 00:00:00 2001 > From: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx> > Date: Thu, 22 Mar 2018 19:44:12 +0900 > Subject: [PATCH] mm,oom_reaper: Check for MMF_OOM_SKIP before complain. > > I got "oom_reaper: unable to reap pid:" messages when the victim thread > was blocked inside free_pgtables() (which occurred after returning from > unmap_vmas() and setting MMF_OOM_SKIP). We don't need to complain when > exit_mmap() already set MMF_OOM_SKIP. ... because we do not report a failure when MMF_OOM_SKIP is set already (see __oom_reap_task_mm). > [ 663.593821] Killed process 7558 (a.out) total-vm:4176kB, anon-rss:84kB, file-rss:0kB, shmem-rss:0kB > [ 664.684801] oom_reaper: unable to reap pid:7558 (a.out) > [ 664.892292] a.out D13272 7558 6931 0x00100084 > [ 664.895765] Call Trace: > [ 664.897574] ? __schedule+0x25f/0x780 > [ 664.900099] schedule+0x2d/0x80 > [ 664.902260] rwsem_down_write_failed+0x2bb/0x440 > [ 664.905249] ? rwsem_down_write_failed+0x55/0x440 > [ 664.908335] ? free_pgd_range+0x569/0x5e0 > [ 664.911145] call_rwsem_down_write_failed+0x13/0x20 > [ 664.914121] down_write+0x49/0x60 > [ 664.916519] ? unlink_file_vma+0x28/0x50 > [ 664.919255] unlink_file_vma+0x28/0x50 > [ 664.922234] free_pgtables+0x36/0x100 > [ 664.924797] exit_mmap+0xbb/0x180 > [ 664.927220] mmput+0x50/0x110 > [ 664.929504] copy_process.part.41+0xb61/0x1fe0 > [ 664.932448] ? _do_fork+0xe6/0x560 > [ 664.934902] ? _do_fork+0xe6/0x560 > [ 664.937361] _do_fork+0xe6/0x560 > [ 664.939742] ? syscall_trace_enter+0x1a9/0x240 > [ 664.942693] ? retint_user+0x18/0x18 > [ 664.945309] ? page_fault+0x2f/0x50 > [ 664.947896] ? trace_hardirqs_on_caller+0x11f/0x1b0 > [ 664.951075] do_syscall_64+0x74/0x230 > [ 664.953747] entry_SYSCALL_64_after_hwframe+0x42/0xb7 > > Signed-off-by: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx> > Acked-by: David Rientjes <rientjes@xxxxxxxxxx> > Cc: Michal Hocko <mhocko@xxxxxxxx> OK, fair enough. I think it is on borderline of usefulness but it doesn't seem harmful. I can already see somebody asking why the MMF_OOM_SKIP really requires mmap_sem in __oom_reap_task_mm while it doesn't in oom_reap_task but what ever. Acked-by: Michal Hocko <mhocko@xxxxxxxx> > --- > mm/oom_kill.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/mm/oom_kill.c b/mm/oom_kill.c > index 5336985..dfd3705 100644 > --- a/mm/oom_kill.c > +++ b/mm/oom_kill.c > @@ -590,7 +590,8 @@ static void oom_reap_task(struct task_struct *tsk) > while (attempts++ < MAX_OOM_REAP_RETRIES && !__oom_reap_task_mm(tsk, mm)) > schedule_timeout_idle(HZ/10); > > - if (attempts <= MAX_OOM_REAP_RETRIES) > + if (attempts <= MAX_OOM_REAP_RETRIES || > + test_bit(MMF_OOM_SKIP, &mm->flags)) > goto done; > > > -- > 1.8.3.1 -- Michal Hocko SUSE Labs
