mm/hwpoison: fix PageHWPoison test/set race
There is a race between madvise_hwpoison path and memory_failure:
CPU0 CPU1
madvise_hwpoison
get_user_pages_fast
PageHWPoison check (false)
memory_failure
TestSetPageHWPoison
soft_offline_page
PageHWPoison check (true)
return -EBUSY (without put_page)
Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com>
Suggested-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index 8ad923a..863544d 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -1719,6 +1719,8 @@
if (PageHWPoison(page)) {
pr_info("soft offline: %#lx page already poisoned\n", pfn);
+ if (flags & MF_COUNT_INCREASED)
+ put_page(page);
return -EBUSY;
}
if (!PageHuge(page) && PageTransHuge(hpage)) {