From: David Rientjes <rientjes@google.com>
To: Vlastimil Babka <vbabka@suse.cz>
Cc: Michal Hocko <mhocko@suse.cz>, Holger Kiehl <Holger.Kiehl@dwd.de>,
linux-kernel <linux-kernel@vger.kernel.org>,
Mel Gorman <mgorman@suse.de>,
linux-mm@kvack.org
Subject: Re: Need help in bug in isolate_migratepages_range
Date: Mon, 3 Feb 2014 16:06:51 -0800 (PST) [thread overview]
Message-ID: <alpine.DEB.2.02.1402031602060.10778@chino.kir.corp.google.com> (raw)
In-Reply-To: <52EFC93D.3030106@suse.cz>
On Mon, 3 Feb 2014, Vlastimil Babka wrote:
> It seems to come from balloon_page_movable() and its test page_count(page) ==
> 1.
>
Hmm, I think it might be because compound_head() == NULL here. Holger,
this looks like a race condition when allocating a compound page, did you
only see it once or is it actually reproducible?
I think this happens when a new compound page is allocated and PageBuddy
is cleared before prep_compound_page() and then we see PageTail(p) set but
p->first_page is not yet initialized. Is there any way to avoid memory
barriers in compound_page()?
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next prev parent reply other threads:[~2014-02-04 0:06 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <alpine.LRH.2.02.1401312037340.6630@diagnostix.dwd.de>
2014-02-03 12:20 ` Michal Hocko
2014-02-03 14:29 ` Holger Kiehl
2014-02-03 16:20 ` Michal Hocko
2014-02-03 16:52 ` Vlastimil Babka
2014-02-04 0:06 ` David Rientjes [this message]
2014-02-04 7:17 ` Holger Kiehl
2014-02-05 0:02 ` [patch] mm, page_alloc: make first_page visible before PageTail David Rientjes
2014-02-05 0:06 ` Andrew Morton
2014-02-05 0:14 ` David Rientjes
2014-02-05 0:22 ` [patch v2] " David Rientjes
2014-02-05 8:42 ` Michal Hocko
2014-02-12 9:00 ` [patch -mm] mm: close PageTail race David Rientjes
2014-02-03 19:50 ` Need help in bug in isolate_migratepages_range Holger Kiehl
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