The patch titled
Subject: mm: check_new_page_bad() directly returns in __PG_HWPOISON case
has been added to the -mm tree. Its filename is
mm-check_new_page_bad-directly-returns-in-__pg_hwpoison-case.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-check_new_page_bad-directly-returns-in-__pg_hwpoison-case.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-check_new_page_bad-directly-returns-in-__pg_hwpoison-case.patch
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------------------------------------------------------
From: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
Subject: mm: check_new_page_bad() directly returns in __PG_HWPOISON case
Currently we check page->flags twice for "HWPoisoned" case of
check_new_page_bad(), which can cause a race with unpoisoning.
This race unnecessarily taints kernel with "BUG: Bad page state".
check_new_page_bad() is the only caller of bad_page() which is interested
in __PG_HWPOISON, so let's move the hwpoison related code in bad_page()
to it.
Link: http://lkml.kernel.org/r/20160518100949.GA17299@xxxxxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
Acked-by: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/page_alloc.c | 9 +++------
1 file changed, 3 insertions(+), 6 deletions(-)
diff -puN mm/page_alloc.c~mm-check_new_page_bad-directly-returns-in-__pg_hwpoison-case mm/page_alloc.c
--- a/mm/page_alloc.c~mm-check_new_page_bad-directly-returns-in-__pg_hwpoison-case
+++ a/mm/page_alloc.c
@@ -522,12 +522,6 @@ static void bad_page(struct page *page,
static unsigned long nr_shown;
static unsigned long nr_unshown;
- /* Don't complain about poisoned pages */
- if (PageHWPoison(page)) {
- page_mapcount_reset(page); /* remove PageBuddy */
- return;
- }
-
/*
* Allow a burst of 60 reports, then keep quiet for that minute;
* or allow a steady drip of one report per second.
@@ -1654,6 +1648,9 @@ static void check_new_page_bad(struct pa
if (unlikely(page->flags & __PG_HWPOISON)) {
bad_reason = "HWPoisoned (hardware-corrupted)";
bad_flags = __PG_HWPOISON;
+ /* Don't complain about hwpoisoned pages */
+ page_mapcount_reset(page); /* remove PageBuddy */
+ return;
}
if (unlikely(page->flags & PAGE_FLAGS_CHECK_AT_PREP)) {
bad_reason = "PAGE_FLAGS_CHECK_AT_PREP flag set";
_
Patches currently in -mm which might be from n-horiguchi@xxxxxxxxxxxxx are
mm-check_new_page_bad-directly-returns-in-__pg_hwpoison-case.patch
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