Re: [patch 09/11] mm, page_alloc: allow system oom handlers to use memory reserves

Tejun Heo
2014-03-06T21:13:37Z

On Tue, Mar 04, 2014 at 07:59:35PM -0800, David Rientjes wrote:
> The root memcg allows unlimited memory charging, so no memory may be
> reserved for userspace oom handlers that are responsible for dealing
> with system oom conditions.
>
> Instead, this memory must come from per-zone memory reserves. This
> allows the memory allocation to succeed, and the memcg charge will
> naturally succeed afterwards.
>
> This patch introduces per-zone oom watermarks that aren't really
> watermarks in the traditional sense. The oom watermark is the root
> memcg's oom reserve proportional to the size of the zone. When a page
> allocation is done, the effective watermark is
>
> [min/low/high watermark] - [oom watermark]
>
> For the [min watermark] case, this is effectively the oom reserve.
> However, it also adjusts the low and high watermark accordingly so
> memory is actually only allocated from min reserves when appropriate.
>
> Signed-off-by: David Rientjes <rientjes@google.com>

Until consensus on the whole approach can be reached,

Nacked-by: Tejun Heo <tj@kernel.org>

Thanks.

--
tejun