[PATCH 3.14 09/51] mm: soft-offline: fix num_poisoned_pages counting on concurrent events

Greg Kroah-Hartman
2015-05-15T23:36:38Z

From: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>

commit 602498f9aa43d4951eece3fd6ad95a6d0a78d537 upstream.

If multiple soft offline events hit one free page/hugepage concurrently,
soft_offline_page() can handle the free page/hugepage multiple times,
which makes num_poisoned_pages counter increased more than once. This
patch fixes this wrong counting by checking TestSetPageHWPoison for normal
papes and by checking the return value of dequeue_hwpoisoned_huge_page()
for hugepages.

Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Acked-by: Dean Nelson <dnelson@redhat.com>
Cc: Andi Kleen <andi@firstfloor.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
mm/memory-failure.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -1723,12 +1723,12 @@ int soft_offline_page(struct page *page,
} else if (ret == 0) { /* for free pages */
if (PageHuge(page)) {
set_page_hwpoison_huge_page(hpage);
- dequeue_hwpoisoned_huge_page(hpage);
- atomic_long_add(1 << compound_order(hpage),
+ if (!dequeue_hwpoisoned_huge_page(hpage))
+ atomic_long_add(1 << compound_order(hpage),
&num_poisoned_pages);
} else {
- SetPageHWPoison(page);
- atomic_long_inc(&num_poisoned_pages);
+ if (!TestSetPageHWPoison(page))
+ atomic_long_inc(&num_poisoned_pages);
}
}
unset_migratetype_isolate(page, MIGRATE_MOVABLE);