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From: Mel Gorman <mgorman@techsingularity.net>
To: Vlastimil Babka <vbabka@suse.cz>
Cc: Ganapatrao Kulkarni <gpkulkarni@gmail.com>,
	Michal Hocko <mhocko@kernel.org>,
	linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [RFC 2/4] mm, page_alloc: fix fast-path race with cpuset update or removal
Date: Wed, 18 Jan 2017 09:46:15 +0000	[thread overview]
Message-ID: <20170118094615.eif2xez65hpmvdnr@techsingularity.net> (raw)
In-Reply-To: <20170117221610.22505-3-vbabka@suse.cz>

On Tue, Jan 17, 2017 at 11:16:08PM +0100, Vlastimil Babka wrote:
> Ganapatrao Kulkarni reported that the LTP test cpuset01 in stress mode triggers
> OOM killer in few seconds, despite lots of free memory. The test attemps to
> repeatedly fault in memory in one process in a cpuset, while changing allowed
> nodes of the cpuset between 0 and 1 in another process.
> 
> One possible cause is that in the fast path we find the preferred zoneref
> according to current mems_allowed, so that it points to the middle of the
> zonelist, skipping e.g. zones of node 1 completely. If the mems_allowed is
> updated to contain only node 1, we never reach it in the zonelist, and trigger
> OOM before checking the cpuset_mems_cookie.
> 
> This patch fixes the particular case by redoing the preferred zoneref search
> if we switch back to the original nodemask. The condition is also slightly
> changed so that when the last non-root cpuset is removed, we don't miss it.
> 
> Note that this is not a full fix, and more patches will follow.
> 
> Reported-by: Ganapatrao Kulkarni <gpkulkarni@gmail.com>
> Fixes: 682a3385e773 ("mm, page_alloc: inline the fast path of the zonelist iterator")
> Signed-off-by: Vlastimil Babka <vbabka@suse.cz>

Acked-by: Mel Gorman <mgorman@techsingularity.net>

-- 
Mel Gorman
SUSE Labs

WARNING: multiple messages have this Message-ID (diff)
From: Mel Gorman <mgorman@techsingularity.net>
To: Vlastimil Babka <vbabka@suse.cz>
Cc: Ganapatrao Kulkarni <gpkulkarni@gmail.com>,
	Michal Hocko <mhocko@kernel.org>,
	linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [RFC 2/4] mm, page_alloc: fix fast-path race with cpuset update or removal
Date: Wed, 18 Jan 2017 09:46:15 +0000	[thread overview]
Message-ID: <20170118094615.eif2xez65hpmvdnr@techsingularity.net> (raw)
In-Reply-To: <20170117221610.22505-3-vbabka@suse.cz>

On Tue, Jan 17, 2017 at 11:16:08PM +0100, Vlastimil Babka wrote:
> Ganapatrao Kulkarni reported that the LTP test cpuset01 in stress mode triggers
> OOM killer in few seconds, despite lots of free memory. The test attemps to
> repeatedly fault in memory in one process in a cpuset, while changing allowed
> nodes of the cpuset between 0 and 1 in another process.
> 
> One possible cause is that in the fast path we find the preferred zoneref
> according to current mems_allowed, so that it points to the middle of the
> zonelist, skipping e.g. zones of node 1 completely. If the mems_allowed is
> updated to contain only node 1, we never reach it in the zonelist, and trigger
> OOM before checking the cpuset_mems_cookie.
> 
> This patch fixes the particular case by redoing the preferred zoneref search
> if we switch back to the original nodemask. The condition is also slightly
> changed so that when the last non-root cpuset is removed, we don't miss it.
> 
> Note that this is not a full fix, and more patches will follow.
> 
> Reported-by: Ganapatrao Kulkarni <gpkulkarni@gmail.com>
> Fixes: 682a3385e773 ("mm, page_alloc: inline the fast path of the zonelist iterator")
> Signed-off-by: Vlastimil Babka <vbabka@suse.cz>

Acked-by: Mel Gorman <mgorman@techsingularity.net>

-- 
Mel Gorman
SUSE Labs

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  parent reply	other threads:[~2017-01-18  9:46 UTC|newest]

Thread overview: 46+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-01-17 22:16 [RFC 0/4] fix premature OOM due to cpuset races Vlastimil Babka
2017-01-17 22:16 ` Vlastimil Babka
2017-01-17 22:16 ` [RFC 1/4] mm, page_alloc: fix check for NULL preferred_zone Vlastimil Babka
2017-01-17 22:16   ` Vlastimil Babka
2017-01-18  9:31   ` Michal Hocko
2017-01-18  9:31     ` Michal Hocko
2017-01-18  9:45     ` Vlastimil Babka
2017-01-18  9:45       ` Vlastimil Babka
2017-01-18  9:53       ` Michal Hocko
2017-01-18  9:53         ` Michal Hocko
2017-01-18  9:45   ` Mel Gorman
2017-01-18  9:45     ` Mel Gorman
2017-01-17 22:16 ` [RFC 2/4] mm, page_alloc: fix fast-path race with cpuset update or removal Vlastimil Babka
2017-01-17 22:16   ` Vlastimil Babka
2017-01-18  9:34   ` Michal Hocko
2017-01-18  9:34     ` Michal Hocko
2017-01-18  9:46   ` Mel Gorman [this message]
2017-01-18  9:46     ` Mel Gorman
2017-01-17 22:16 ` [RFC 3/4] mm, page_alloc: move cpuset seqcount checking to slowpath Vlastimil Babka
2017-01-17 22:16   ` Vlastimil Babka
2017-01-18  7:22   ` Hillf Danton
2017-01-18  7:22     ` Hillf Danton
2017-01-18  9:26     ` Vlastimil Babka
2017-01-18  9:26       ` Vlastimil Babka
2017-01-18  9:40   ` Michal Hocko
2017-01-18  9:40     ` Michal Hocko
2017-01-18  9:48     ` Vlastimil Babka
2017-01-18  9:48       ` Vlastimil Babka
2017-01-18  9:55       ` Michal Hocko
2017-01-18  9:55         ` Michal Hocko
2017-01-18 10:03   ` Mel Gorman
2017-01-18 10:03     ` Mel Gorman
2017-01-17 22:16 ` [RFC 4/4] mm, page_alloc: fix premature OOM when racing with cpuset mems update Vlastimil Babka
2017-01-17 22:16   ` Vlastimil Babka
2017-01-18  7:12   ` Hillf Danton
2017-01-18  7:12     ` Hillf Danton
2017-01-18  9:32     ` Vlastimil Babka
2017-01-18  9:32       ` Vlastimil Babka
2017-01-18 10:08   ` Mel Gorman
2017-01-18 10:08     ` Mel Gorman
2017-01-18  9:19 ` [RFC 0/4] fix premature OOM due to cpuset races Michal Hocko
2017-01-18  9:19   ` Michal Hocko
2017-01-18 16:20 ` [RFC 5/4] mm, page_alloc: fix premature OOM due to vma mempolicy update Vlastimil Babka
2017-01-18 16:20   ` Vlastimil Babka
2017-01-18 16:23   ` Vlastimil Babka
2017-01-18 16:23     ` Vlastimil Babka

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