Re: [patch] mm: disable user interface to manually rescueunevictable pages

[KAMEZAWA Hiroyuki]

On Tue, 27 Sep 2011 09:27:14 +0200
Johannes Weiner <jweiner@xxxxxxxxxx> wrote:

> At one point, anonymous pages were supposed to go on the unevictable
> list when no swap space was configured, and the idea was to manually
> rescue those pages after adding swap and making them evictable again.
> But nowadays, swap-backed pages on the anon LRU list are not scanned
> without available swap space anyway, so there is no point in moving
> them to a separate list anymore.
> 
> The manual rescue could also be used in case pages were stranded on
> the unevictable list due to race conditions.  But the code has been
> around for a while now and newly discovered bugs should be properly
> reported and dealt with instead of relying on such a manual fixup.
> 
> In addition to the lack of a usecase, the sysfs interface to rescue
> pages from a specific NUMA node has been broken since its
> introduction, so it's unlikely that anybody ever relied on that.
> 
> This patch removes the functionality behind the sysctl and the
> node-interface and emits a one-time warning when somebody tries to
> access either of them.
> 
> Signed-off-by: Johannes Weiner <jweiner@xxxxxxxxxx>
> Reported-by: Kautuk Consul <consul.kautuk@xxxxxxxxx>

Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>

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