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05 April 2024, 19:05:47 UTC
Revision 47aee4d8e314384807e98b67ade07f6da476aa75 authored by Minchan Kim on 22 October 2015, 20:32:19 UTC, committed by Linus Torvalds on 23 October 2015, 08:55:10 UTC 
thp: use is_zero_pfn() only after pte_present() check
 
Use is_zero_pfn() on pteval only after pte_present() check on pteval
(It might be better idea to introduce is_zero_pte() which checks
pte_present() first).

Otherwise when working on a swap or migration entry and if pte_pfn's
result is equal to zero_pfn by chance, we lose user's data in
__collapse_huge_page_copy().  So if you're unlucky, the application
segfaults and finally you could see below message on exit:

BUG: Bad rss-counter state mm:ffff88007f099300 idx:2 val:3

Fixes: ca0984caa823 ("mm: incorporate zero pages into transparent huge pages")
Signed-off-by: Minchan Kim <minchan@kernel.org>
Reviewed-by: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Mel Gorman <mgorman@suse.de>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Hugh Dickins <hughd@google.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: <stable@vger.kernel.org>	[4.1+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1 parent b8fa0ef
History
Tip revision: 47aee4d8e314384807e98b67ade07f6da476aa75 authored by Minchan Kim on 22 October 2015, 20:32:19 UTC
thp: use is_zero_pfn() only after pte_present() check
Tip revision: 47aee4d
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