On Thu 22-12-16 21:57:30, Tetsuo Handa wrote:
> Since commit 862e3073b3eed13f
> ("mm, oom: get rid of signal_struct::oom_victims")
> changed to wait until MMF_OOM_SKIP is set rather than wait while
> TIF_MEMDIE is set, rationale comment for commit e2fe14564d3316d1
> ("oom_reaper: close race with exiting task") needs to be updated.
>
> Signed-off-by: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
> ---
> mm/oom_kill.c | 15 +++------------
> 1 file changed, 3 insertions(+), 12 deletions(-)
>
> diff --git a/mm/oom_kill.c b/mm/oom_kill.c
> index ec9f11d..6fd076b 100644
> --- a/mm/oom_kill.c
> +++ b/mm/oom_kill.c
> @@ -470,18 +470,9 @@ static bool __oom_reap_task_mm(struct task_struct *tsk, struct mm_struct *mm)
> bool ret = true;
>
> /*
> - * We have to make sure to not race with the victim exit path
> - * and cause premature new oom victim selection:
> - * __oom_reap_task_mm exit_mm
> - * mmget_not_zero
> - * mmput
> - * atomic_dec_and_test
> - * exit_oom_victim
> - * [...]
> - * out_of_memory
> - * select_bad_process
> - * # no TIF_MEMDIE task selects new victim
> - * unmap_page_range # frees some memory
> + * Make sure that other threads waiting for oom_lock at
> + * __alloc_pages_may_oom() are given a chance to call
> + * get_page_from_freelist() after MMF_OOM_SKIP is set.
> */
> mutex_lock(&oom_lock);
I am not sure the comment clarifies things. I would either remove the
comment completely or write something like the below
/*
* Exclude any oom actions while we are reaping the oom
* victim. This will save us from pointless searching of the
* new oom victim.
*/
--
Michal Hocko
SUSE Labs
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