Re: [PATCH] memcg: fix memory.high target

From: Johannes Weiner
Date: Mon Nov 23 2015 - 11:18:21 EST

On Mon, Nov 23, 2015 at 03:22:31PM +0300, Vladimir Davydov wrote:
> When the memory.high threshold is exceeded, try_charge() schedules a
> task_work to reclaim the excess. The reclaim target is set to the number
> of pages requested by try_charge(). This is wrong, because try_charge()
> usually charges more pages than requested (batch > nr_pages) in order to
> refill per cpu stocks. As a result, a process in a cgroup can easily
> exceed memory.high significantly when doing a lot of charges w/o
> returning to userspace (e.g. reading a file in big chunks).
> Fix this issue by assuring that when exceeding memory.high a process
> reclaims as many pages as were actually charged (i.e. batch).
> Signed-off-by: Vladimir Davydov <vdavydov@xxxxxxxxxxxxx>

Acked-by: Johannes Weiner <hannes@xxxxxxxxxxx>
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