mm/memory-failure.c: use compound_head() flags for huge pages

memory_failure() chooses a recovery action function based on the page
flags.  For huge pages it uses the tail page flags which don't have
anything interesting set, resulting in:

> Memory failure: 0x9be3b4: Unknown page state
> Memory failure: 0x9be3b4: recovery action for unknown page: Failed

Instead, save a copy of the head page's flags if this is a huge page,
this means if there are no relevant flags for this tail page, we use the
head pages flags instead.  This results in the me_huge_page() recovery
action being called:

> Memory failure: 0x9b7969: recovery action for huge page: Delayed

For hugepages that have not yet been allocated, this allows the hugepage
to be dequeued.

Fixes: 524fca1e7356 ("HWPOISON: fix misjudgement of page_action() for errors on mlocked pages")
Link: http://lkml.kernel.org/r/20170524130204.21845-1-james.morse@arm.com
Signed-off-by: James Morse <james.morse@arm.com>
Tested-by: Punit Agrawal <punit.agrawal@arm.com>
Acked-by: Punit Agrawal <punit.agrawal@arm.com>
Acked-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: <stable@vger.kernel.org>
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 342fac9ba89b0da3e207b1fdaef2be71c9837a24..ecc183fd94f36f35e91b69c6a06930bb456a7e86 100644 (file)
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -1184,7 +1184,10 @@ int memory_failure(unsigned long pfn, int trapno, int flags)
         * page_remove_rmap() in try_to_unmap_one(). So to determine page status
         * correctly, we save a copy of the page flags at this time.
         */
-       page_flags = p->flags;
+       if (PageHuge(p))
+               page_flags = hpage->flags;
+       else
+               page_flags = p->flags;
 
        /*
         * unpoison always clear PG_hwpoison inside page lock