linux-kernel - Re: [PATCH 2/5] oom reaper: handle mlocked pages

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Message-ID: <alpine.DEB.2.10.1602031557320.10331@chino.kir.corp.google.com>
Date:	Wed, 3 Feb 2016 15:57:51 -0800 (PST)
From:	David Rientjes <rientjes@...gle.com>
To:	Michal Hocko <mhocko@...nel.org>
cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Mel Gorman <mgorman@...e.de>,
	Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>,
	Oleg Nesterov <oleg@...hat.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Hugh Dickins <hughd@...gle.com>,
	Andrea Argangeli <andrea@...nel.org>,
	Rik van Riel <riel@...hat.com>, linux-mm@...ck.org,
	LKML <linux-kernel@...r.kernel.org>,
	Michal Hocko <mhocko@...e.com>
Subject: Re: [PATCH 2/5] oom reaper: handle mlocked pages

On Wed, 3 Feb 2016, Michal Hocko wrote:

> From: Michal Hocko <mhocko@...e.com>
> 
> __oom_reap_vmas current skips over all mlocked vmas because they need a
> special treatment before they are unmapped. This is primarily done for
> simplicity. There is no reason to skip over them and reduce the amount
> of reclaimed memory. This is safe from the semantic point of view
> because try_to_unmap_one during rmap walk would keep tell the reclaim
> to cull the page back and mlock it again.
> 
> munlock_vma_pages_all is also safe to be called from the oom reaper
> context because it doesn't sit on any locks but mmap_sem (for read).
> 
> Signed-off-by: Michal Hocko <mhocko@...e.com>

Acked-by: David Rientjes <rientjes@...gle.com>