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authorHugh Dickins <hughd@google.com>2012-11-16 14:15:03 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2012-11-16 14:33:04 -0800
commit215c02bc33bbd5ff4d7379a909462d11f0103218 (patch)
treefa07d774e4b60404727ca0a8d54044d439eef905 /mm/bootmem.c
parent498c2280212327858e521e9d21345d4cc2637f54 (diff)
downloadlinux-215c02bc33bbd5ff4d7379a909462d11f0103218.tar.gz
tmpfs: fix shmem_getpage_gfp() VM_BUG_ON
Fuzzing with trinity hit the "impossible" VM_BUG_ON(error) (which Fedora has converted to WARNING) in shmem_getpage_gfp(): WARNING: at mm/shmem.c:1151 shmem_getpage_gfp+0xa5c/0xa70() Pid: 29795, comm: trinity-child4 Not tainted 3.7.0-rc2+ #49 Call Trace: warn_slowpath_common+0x7f/0xc0 warn_slowpath_null+0x1a/0x20 shmem_getpage_gfp+0xa5c/0xa70 shmem_fault+0x4f/0xa0 __do_fault+0x71/0x5c0 handle_pte_fault+0x97/0xae0 handle_mm_fault+0x289/0x350 __do_page_fault+0x18e/0x530 do_page_fault+0x2b/0x50 page_fault+0x28/0x30 tracesys+0xe1/0xe6 Thanks to Johannes for pointing to truncation: free_swap_and_cache() only does a trylock on the page, so the page lock we've held since before confirming swap is not enough to protect against truncation. What cleanup is needed in this case? Just delete_from_swap_cache(), which takes care of the memcg uncharge. Signed-off-by: Hugh Dickins <hughd@google.com> Reported-by: Dave Jones <davej@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/bootmem.c')
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