Re: [patch 1/2] mm: page_alloc: reset aging cycle with GFP_THISNODE

[Rik van Riel]

On 02/26/2014 03:13 PM, Johannes Weiner wrote:

> Would this be an acceptable replacement for 1/2?

Looks reasonable to me. This should avoid the issues that
were observed with NUMA migrations.

> ---
>
> From: Johannes Weiner <hannes@xxxxxxxxxxx>
> Subject: [patch 1/2] mm: page_alloc: exempt GFP_THISNODE allocations from zone
>   fairness
>
> Jan Stancek reports manual page migration encountering allocation
> failures after some pages when there is still plenty of memory free,
> and bisected the problem down to 81c0a2bb515f ("mm: page_alloc: fair
> zone allocator policy").
>
> The problem is that GFP_THISNODE obeys the zone fairness allocation
> batches on one hand, but doesn't reset them and wake kswapd on the
> other hand.  After a few of those allocations, the batches are
> exhausted and the allocations fail.
>
> Fixing this means either having GFP_THISNODE wake up kswapd, or
> GFP_THISNODE not participating in zone fairness at all.  The latter
> seems safer as an acute bugfix, we can clean up later.
>
> Reported-by: Jan Stancek <jstancek@xxxxxxxxxx>
> Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx>
> Cc: <stable@xxxxxxxxxx> # 3.12+

Acked-by: Rik van Riel <riel@xxxxxxxxxx>

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