diff options
| author | Hugh Dickins <hughd@google.com> | 2018-11-30 14:10:47 -0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-12-05 19:42:38 +0100 |
| commit | dc62803e271decb287929d44789fe9170eec5ba7 (patch) | |
| tree | 4dff193c0dc6aadafa13d07f081c337fc9df92da /mm/cma_debug.c | |
| parent | 8dcbb5f21567c3a85a7e4ec781d0e49ea174397d (diff) | |
mm/khugepaged: collapse_shmem() do not crash on Compound
commit 06a5e1268a5fb9c2b346a3da6b97e85f2eba0f07 upstream.
collapse_shmem()'s VM_BUG_ON_PAGE(PageTransCompound) was unsafe: before
it holds page lock of the first page, racing truncation then extension
might conceivably have inserted a hugepage there already. Fail with the
SCAN_PAGE_COMPOUND result, instead of crashing (CONFIG_DEBUG_VM=y) or
otherwise mishandling the unexpected hugepage - though later we might
code up a more constructive way of handling it, with SCAN_SUCCESS.
Link: http://lkml.kernel.org/r/alpine.LSU.2.11.1811261529310.2275@eggly.anvils
Fixes: f3f0e1d2150b2 ("khugepaged: add support of collapse for tmpfs/shmem pages")
Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: <stable@vger.kernel.org> [4.8+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'mm/cma_debug.c')
0 files changed, 0 insertions, 0 deletions