On Fri 20-05-16 23:08:47, Tetsuo Handa wrote:
> mem_cgroup_out_of_memory() is returning "true" if it finds a TIF_MEMDIE
> task after an eligible task was found, "false" if it found a TIF_MEMDIE
> task before an eligible task is found.
>
> This difference confuses memory_max_write() which checks the return value
> of mem_cgroup_out_of_memory(). Since memory_max_write() wants to continue
> looping, mem_cgroup_out_of_memory() should return "true" in this case.
>
> This patch sets a dummy pointer in order to return "true".
>
> Signed-off-by: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
Fixes: b6e6edcfa405 ("mm: memcontrol: reclaim and OOM kill when
shrinking memory.max below usage")
But I do not think this is really worth backporting to stable tree (once
it is established).
> Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
> Cc: Michal Hocko <mhocko@xxxxxxxxxx>
> Cc: Vladimir Davydov <vdavydov@xxxxxxxxxxxxx>
Acked-by: Michal Hocko <mhocko@xxxxxxxx>
> ---
> mm/memcontrol.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index b3f16ab..ab574d8 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -1302,6 +1302,8 @@ static bool mem_cgroup_out_of_memory(struct mem_cgroup *memcg, gfp_t gfp_mask,
> mem_cgroup_iter_break(memcg, iter);
> if (chosen)
> put_task_struct(chosen);
> + /* Set a dummy value to return "true". */
> + chosen = (void *) 1;
> goto unlock;
> case OOM_SCAN_OK:
> break;
> --
> 1.8.3.1
--
Michal Hocko
SUSE Labs
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