tree 7a5db8c33f69e58aa68445bd4d4d5d289ee719d1
parent 6d04399040ca9058c12c766bbbefbf6acdb2eabe
author Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> 1361579751 -0800
committer Linus Torvalds <torvalds@linux-foundation.org> 1361670622 -0800

HWPOISON: fix misjudgement of page_action() for errors on mlocked pages

memory_failure() can't handle memory errors on mlocked pages correctly,
because page_action() judges such errors as ones on "unknown pages"
instead of ones on "unevictable LRU page" or "mlocked LRU page".  In
order to determine page_state page_action() checks page flags at the
timing of the judgement, but such page flags are not the same with those
just after memory_failure() is called, because memory_failure() does
unmapping of the error pages before doing page_action().  This unmapping
changes the page state, especially page_remove_rmap() (called from
try_to_unmap_one()) clears PG_mlocked, so page_action() can't catch
mlocked pages after that.

With this patch, we store the page flag of the error page before doing
unmap, and (only) if the first check with page flags at the time decided
the error page is unknown, we do the second check with the stored page
flag.  This implementation doesn't change error handling for the page
types for which the first check can determine the page state correctly.

[akpm@linux-foundation.org: tweak comments]
Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Chen Gong <gong.chen@linux.intel.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>