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SubjectRe: 4.8.8 kernel trigger OOM killer repeatedly when I have lots of RAM that should be free
Marc, could you try this patch please? I think it should be pretty clear
it should help you but running it through your use case would be more
than welcome before I ask Greg to take this to the 4.8 stable tree.

Thanks!

On Wed 23-11-16 07:34:10, Michal Hocko wrote:
[...]
> commit b2ccdcb731b666aa28f86483656c39c5e53828c7
> Author: Michal Hocko <mhocko@suse.com>
> Date: Wed Nov 23 07:26:30 2016 +0100
>
> mm, oom: stop pre-mature high-order OOM killer invocations
>
> 31e49bfda184 ("mm, oom: protect !costly allocations some more for
> !CONFIG_COMPACTION") was an attempt to reduce chances of pre-mature OOM
> killer invocation for high order requests. It seemed to work for most
> users just fine but it is far from bullet proof and obviously not
> sufficient for Marc who has reported pre-mature OOM killer invocations
> with 4.8 based kernels. 4.9 will all the compaction improvements seems
> to be behaving much better but that would be too intrusive to backport
> to 4.8 stable kernels. Instead this patch simply never declares OOM for
> !costly high order requests. We rely on order-0 requests to do that in
> case we are really out of memory. Order-0 requests are much more common
> and so a risk of a livelock without any way forward is highly unlikely.
>
> Reported-by: Marc MERLIN <marc@merlins.org>
> Signed-off-by: Michal Hocko <mhocko@suse.com>
>
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index a2214c64ed3c..7401e996009a 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -3161,6 +3161,16 @@ should_compact_retry(struct alloc_context *ac, unsigned int order, int alloc_fla
> if (!order || order > PAGE_ALLOC_COSTLY_ORDER)
> return false;
>
> +#ifdef CONFIG_COMPACTION
> + /*
> + * This is a gross workaround to compensate a lack of reliable compaction
> + * operation. We cannot simply go OOM with the current state of the compaction
> + * code because this can lead to pre mature OOM declaration.
> + */
> + if (order <= PAGE_ALLOC_COSTLY_ORDER)
> + return true;
> +#endif
> +
> /*
> * There are setups with compaction disabled which would prefer to loop
> * inside the allocator rather than hit the oom killer prematurely.
> --
> Michal Hocko
> SUSE Labs

--
Michal Hocko
SUSE Labs

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