linux-kernel - Re: [PATCH for 3.2.34] memcg: do not trigger OOM from add_to_page_cache

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Date:	Thu, 06 Dec 2012 01:29:24 +0100
From:	"azurIt" <azurit@...ox.sk>
To:	Michal Hocko <mhocko@...e.cz>
Cc:	<linux-kernel@...r.kernel.org>, <linux-mm@...ck.org>,
	cgroups mailinglist <cgroups@...r.kernel.org>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
	Johannes Weiner <hannes@...xchg.org>
Subject: Re: [PATCH for 3.2.34] memcg: do not trigger OOM from add_to_page_cache_locked

>OK, so the ENOMEM seems to be leaking from mem_cgroup_newpage_charge.
>This can only happen if this was an atomic allocation request
>(!__GFP_WAIT) or if oom is not allowed which is the case only for
>transparent huge page allocation.
>The first case can be excluded (in the clean 3.2 stable kernel) because
>all callers of mem_cgroup_newpage_charge use GFP_KERNEL. The later one
>should be OK because the page fault should fallback to a regular page if
>THP allocation/charge fails.
>[/me goes to double check]
>Hmm do_huge_pmd_wp_page seems to charge a huge page and fails with
>VM_FAULT_OOM without any fallback. We should do_huge_pmd_wp_page_fallback
>instead. This has been fixed in 3.5-rc1 by 1f1d06c3 (thp, memcg: split
>hugepage for memcg oom on cow) but it hasn't been backported to 3.2. The
>patch applies to 3.2 without any further modifications. I didn't have
>time to test it but if it helps you we should push this to the stable
>tree.


This, unfortunately, didn't fix the problem :(
http://www.watchdog.sk/lkml/oom_mysqld3
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