Re: [patch 3/3] memcg: never OOM when charging huge pages

[Daisuke Nishimura]

On Thu, 27 Jan 2011 14:47:03 +0100
Johannes Weiner <hannes@xxxxxxxxxxx> wrote:

> Huge page coverage should obviously have less priority than the
> continued execution of a process.
> 
> Never kill a process when charging it a huge page fails.  Instead,
> give up after the first failed reclaim attempt and fall back to
> regular pages.
> 
> Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx>
> ---
>  mm/memcontrol.c |    7 +++++++
>  1 files changed, 7 insertions(+), 0 deletions(-)
> 
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index 17c4e36..2945649 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -1890,6 +1890,13 @@ static int __mem_cgroup_try_charge(struct mm_struct *mm,
>  	int csize = max(CHARGE_SIZE, (unsigned long) page_size);
>  
>  	/*
> +	 * Do not OOM on huge pages.  Fall back to regular pages after
> +	 * the first failed reclaim attempt.
> +	 */
> +	if (page_size > PAGE_SIZE)
> +		oom = false;
> +
> +	/*
>  	 * Unlike gloval-vm's OOM-kill, we're not in memory shortage
>  	 * in system level. So, allow to go ahead dying process in addition to
>  	 * MEMDIE process.
> -- 
> 1.7.3.5
> 
__mem_cgroup_try_charge() has "oom" switch already, so I prefer making callers
use the switch properly by themselves.

Thanks,
Daisuke Nishimura.
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