On Tue 20-03-18 20:57:56, Tetsuo Handa wrote:
> 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
> __oom_reap_task_mm() returned true (by e.g. finding MMF_OOM_SKIP already
> set) when oom_reap_task() was trying MAX_OOM_REAP_RETRIES'th attempt.
>
> [ 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)
I do not see "oom_reaper: reaped process..." so has the task been
reaped?
> [ 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>
> Cc: Michal Hocko <mhocko@xxxxxxxx>
> Cc: David Rientjes <rientjes@xxxxxxxxxx>
> ---
> mm/oom_kill.c | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/mm/oom_kill.c b/mm/oom_kill.c
> index 900300c..1cb2b98 100644
> --- a/mm/oom_kill.c
> +++ b/mm/oom_kill.c
> @@ -588,11 +588,11 @@ static void oom_reap_task(struct task_struct *tsk)
> struct mm_struct *mm = tsk->signal->oom_mm;
>
> /* Retry the down_read_trylock(mmap_sem) a few times */
> - while (attempts++ < MAX_OOM_REAP_RETRIES && !__oom_reap_task_mm(tsk, mm))
> + while (attempts++ < MAX_OOM_REAP_RETRIES) {
> + if (__oom_reap_task_mm(tsk, mm))
> + goto done;
> schedule_timeout_idle(HZ/10);
> -
> - if (attempts <= MAX_OOM_REAP_RETRIES)
> - goto done;
> + }
I do not see how this improves anything. Even if __oom_reap_task_mm
suceeded during the last attempt then attempts == MAX_OOM_REAP_RETRIES
and the if below would bail out. Or what do I miss?
> pr_info("oom_reaper: unable to reap pid:%d (%s)\n",
--
Michal Hocko
SUSE Labs
