From: Mel Gorman <mgorman@techsingularity.net>
To: Minchan Kim <minchan@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Vlastimil Babka <vbabka@suse.cz>,
Joonsoo Kim <iamjoonsoo.kim@lge.com>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
Sangseok Lee <sangseok.lee@lge.com>
Subject: Re: [PATCH 2/4] mm: prevent double decrease of nr_reserved_highatomic
Date: Wed, 12 Oct 2016 06:36:11 +0100 [thread overview]
Message-ID: <20161012053611.GB22174@techsingularity.net> (raw)
In-Reply-To: <1475819136-24358-3-git-send-email-minchan@kernel.org>
On Fri, Oct 07, 2016 at 02:45:34PM +0900, Minchan Kim wrote:
> There is race between page freeing and unreserved highatomic.
>
> CPU 0 CPU 1
>
> free_hot_cold_page
> mt = get_pfnblock_migratetype
> set_pcppage_migratetype(page, mt)
> unreserve_highatomic_pageblock
> spin_lock_irqsave(&zone->lock)
> move_freepages_block
> set_pageblock_migratetype(page)
> spin_unlock_irqrestore(&zone->lock)
> free_pcppages_bulk
> __free_one_page(mt) <- mt is stale
>
> By above race, a page on CPU 0 could go non-highorderatomic free list
> since the pageblock's type is changed. By that, unreserve logic of
> highorderatomic can decrease reserved count on a same pageblock
> several times and then it will make mismatch between
> nr_reserved_highatomic and the number of reserved pageblock.
>
> So, this patch verifies whether the pageblock is highatomic or not
> and decrease the count only if the pageblock is highatomic.
>
> Signed-off-by: Minchan Kim <minchan@kernel.org>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
--
Mel Gorman
SUSE Labs
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
next prev parent reply other threads:[~2016-10-12 5:36 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-10-07 5:45 [PATCH 0/4] use up highorder free pages before OOM Minchan Kim
2016-10-07 5:45 ` [PATCH 1/4] mm: adjust reserved highatomic count Minchan Kim
2016-10-07 12:30 ` Vlastimil Babka
2016-10-07 14:29 ` Minchan Kim
2016-10-10 6:57 ` Vlastimil Babka
2016-10-11 4:19 ` Minchan Kim
2016-10-11 9:40 ` Vlastimil Babka
2016-10-12 5:36 ` Mel Gorman
2016-10-07 5:45 ` [PATCH 2/4] mm: prevent double decrease of nr_reserved_highatomic Minchan Kim
2016-10-07 12:44 ` Vlastimil Babka
2016-10-07 14:30 ` Minchan Kim
2016-10-12 5:36 ` Mel Gorman [this message]
2016-10-07 5:45 ` [PATCH 3/4] mm: unreserve highatomic free pages fully before OOM Minchan Kim
2016-10-07 9:09 ` Michal Hocko
2016-10-07 14:43 ` Minchan Kim
2016-10-10 7:41 ` Michal Hocko
2016-10-11 5:01 ` Minchan Kim
2016-10-11 6:50 ` Michal Hocko
2016-10-11 7:09 ` Minchan Kim
2016-10-11 7:26 ` Michal Hocko
2016-10-11 7:37 ` Minchan Kim
2016-10-11 8:01 ` Michal Hocko
2016-10-07 5:45 ` [PATCH 4/4] mm: skip to reserve pageblock crossed zone boundary for HIGHATOMIC Minchan Kim
2016-10-07 9:16 ` [PATCH 0/4] use up highorder free pages before OOM Michal Hocko
2016-10-07 15:04 ` Minchan Kim
2016-10-10 7:47 ` Michal Hocko
2016-10-11 5:06 ` Minchan Kim
2016-10-11 6:53 ` Michal Hocko
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20161012053611.GB22174@techsingularity.net \
--to=mgorman@techsingularity.net \
--cc=akpm@linux-foundation.org \
--cc=iamjoonsoo.kim@lge.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=minchan@kernel.org \
--cc=sangseok.lee@lge.com \
--cc=vbabka@suse.cz \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).