From: Vlastimil Babka <vbabka@suse.cz>
To: Michal Hocko <mhocko@kernel.org>
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 10:48:55 +0100 [thread overview]
Message-ID: <7b984dde-78c5-2efc-daef-bcdcc51fc9cb@suse.cz> (raw)
In-Reply-To: <20170118094054.GJ7015@dhcp22.suse.cz>
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") ...
WARNING: multiple messages have this Message-ID (diff)
From: Vlastimil Babka <vbabka@suse.cz>
To: Michal Hocko <mhocko@kernel.org>
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 10:48:55 +0100 [thread overview]
Message-ID: <7b984dde-78c5-2efc-daef-bcdcc51fc9cb@suse.cz> (raw)
In-Reply-To: <20170118094054.GJ7015@dhcp22.suse.cz>
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") ...
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next prev parent reply other threads:[~2017-01-18 10:04 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 [this message]
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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