Respectfully revert commit e6ca7b89dc76 "memcg: fix mapcount check
in move charge code for anonymous page" for the 3.3 release, so that
it behaves exactly like releases 2.6.35 through 3.2 in this respect.
Horiguchi-san's commit is correct in itself, 1 makes much more sense
than 2 in that check; but it does not go far enough - swapcount
should be considered too - if we really want such a check at all.
We appear to have reached agreement now, and expect that 3.4 will
remove the mapcount check, but had better not make 3.3 different.
Signed-off-by: Hugh Dickins <hughd@xxxxxxxxxx>
---
mm/memcontrol.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- 3.3-rc6+/mm/memcontrol.c 2012-03-05 22:03:45.940000832 -0800
+++ linux/mm/memcontrol.c 2012-03-09 13:06:41.716250093 -0800
@@ -5075,7 +5075,7 @@ static struct page *mc_handle_present_pt
return NULL;
if (PageAnon(page)) {
/* we don't move shared anon */
- if (!move_anon() || page_mapcount(page) > 1)
+ if (!move_anon() || page_mapcount(page) > 2)
return NULL;
} else if (!move_file())
/* we ignore mapcount for file pages */
--
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