From: Hugh Dickins <hughd@google.com>
Date: Sat, 23 Feb 2013 00:36:09 +0000 (-0800)
Subject: mm,ksm: swapoff might need to copy
X-Git-Tag: v3.9-rc1~99^2~2
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=9e16b7fb1d066d38d01fd57c449f2640c5d208cb;p=pandora-kernel.git

mm,ksm: swapoff might need to copy

Before establishing that KSM page migration was the cause of my
WARN_ON_ONCE(page_mapped(page))s, I suspected that they came from the
lack of a ksm_might_need_to_copy() in swapoff's unuse_pte() - which in
many respects is equivalent to faulting in a page.

In fact I've never caught that as the cause: but in theory it does at
least need the KSM_RUN_UNMERGE check in ksm_might_need_to_copy(), to
avoid bringing a KSM page back in when it's not supposed to be.

I intended to copy how it's done in do_swap_page(), but have a strong
aversion to how "swapcache" ends up being used there: rework it with
"page != swapcache".

Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Petr Holasek <pholasek@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Izik Eidus <izik.eidus@ravellosystems.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

Reading git-diff-tree failed