From: Andrea Arcangeli <aarcange@redhat.com>
Date: Fri, 28 Sep 2012 12:35:31 +0000 (+0200)
Subject: thp: avoid VM_BUG_ON page_count(page) false positives in __collapse_huge_page_copy
X-Git-Tag: v3.6~9
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=99a1300e1d84709f419182bb5189760e78234882;p=pandora-kernel.git

thp: avoid VM_BUG_ON page_count(page) false positives in __collapse_huge_page_copy

Speculative cache pagecache lookups can elevate the refcount from
under us, so avoid the false positive. If the refcount is < 2 we'll be
notified by a VM_BUG_ON in put_page_testzero as there are two
put_page(src_page) in a row before returning from this function.

Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Reviewed-by: Rik van Riel <riel@redhat.com>
Reviewed-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Petr Holasek <pholasek@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

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