From: Michal Hocko <mhocko@kernel.org>
To: Vlastimil Babka <vbabka@suse.cz>
Cc: Mel Gorman <mgorman@techsingularity.net>,
Ganapatrao Kulkarni <gpkulkarni@gmail.com>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [RFC 3/4] mm, page_alloc: move cpuset seqcount checking to slowpath
Date: Wed, 18 Jan 2017 10:55:50 +0100 [thread overview]
Message-ID: <20170118095549.GM7015@dhcp22.suse.cz> (raw)
In-Reply-To: <7b984dde-78c5-2efc-daef-bcdcc51fc9cb@suse.cz>
On Wed 18-01-17 10:48:55, Vlastimil Babka wrote:
> On 01/18/2017 10:40 AM, Michal Hocko wrote:
> > On Tue 17-01-17 23:16:09, Vlastimil Babka wrote:
> > > This is a preparation for the following patch to make review simpler. While
> > > the primary motivation is a bug fix, this could also save some cycles in the
> > > fast path.
> >
> > I cannot say I would be happy about this patch :/ The code is still very
> > confusing and subtle. I really think we should get rid of
> > synchronization with the concurrent cpuset/mempolicy updates instead.
> > Have you considered that instead?
>
> Not so thoroughly yet, but I already suspect it would be intrusive for
> stable. We could make copies of nodemask and mems_allowed and protect just
> the copying with seqcount, but that would mean overhead and stack space.
> Also we might try revert 682a3385e773 ("mm, page_alloc: inline the fast path
> of the zonelist iterator") ...
If reverting that patch makes the problem go away and it is applicable
for the stable I would rather go that way for stable and take a deep
breath and rethink the whole cpuset and nodemask manipulation in the
allocation path for a better long term solution.
--
Michal Hocko
SUSE Labs
WARNING: multiple messages have this Message-ID (diff)
From: Michal Hocko <mhocko@kernel.org>
To: Vlastimil Babka <vbabka@suse.cz>
Cc: Mel Gorman <mgorman@techsingularity.net>,
Ganapatrao Kulkarni <gpkulkarni@gmail.com>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [RFC 3/4] mm, page_alloc: move cpuset seqcount checking to slowpath
Date: Wed, 18 Jan 2017 10:55:50 +0100 [thread overview]
Message-ID: <20170118095549.GM7015@dhcp22.suse.cz> (raw)
In-Reply-To: <7b984dde-78c5-2efc-daef-bcdcc51fc9cb@suse.cz>
On Wed 18-01-17 10:48:55, Vlastimil Babka wrote:
> On 01/18/2017 10:40 AM, Michal Hocko wrote:
> > On Tue 17-01-17 23:16:09, Vlastimil Babka wrote:
> > > This is a preparation for the following patch to make review simpler. While
> > > the primary motivation is a bug fix, this could also save some cycles in the
> > > fast path.
> >
> > I cannot say I would be happy about this patch :/ The code is still very
> > confusing and subtle. I really think we should get rid of
> > synchronization with the concurrent cpuset/mempolicy updates instead.
> > Have you considered that instead?
>
> Not so thoroughly yet, but I already suspect it would be intrusive for
> stable. We could make copies of nodemask and mems_allowed and protect just
> the copying with seqcount, but that would mean overhead and stack space.
> Also we might try revert 682a3385e773 ("mm, page_alloc: inline the fast path
> of the zonelist iterator") ...
If reverting that patch makes the problem go away and it is applicable
for the stable I would rather go that way for stable and take a deep
breath and rethink the whole cpuset and nodemask manipulation in the
allocation path for a better long term solution.
--
Michal Hocko
SUSE Labs
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next prev parent reply other threads:[~2017-01-18 10:15 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
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 [this message]
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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