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| author | Hugh Dickins <hughd@google.com> | 2018-12-01 01:10:25 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-12-05 21:31:57 +0300 |
| commit | 8797f2f4fe0d555d0869b7c2704da146363bd350 (patch) | |
| tree | d8ee78987b645062ac966777d010e4655cf3be29 /mm/khugepaged.c | |
| parent | d31ff4722f45560a6daf3df9d15a6b88da0e5080 (diff) | |
| download | linux-8797f2f4fe0d555d0869b7c2704da146363bd350.tar.xz | |
mm/khugepaged: collapse_shmem() stop if punched or truncated
commit 701270fa193aadf00bdcf607738f64997275d4c7 upstream.
Huge tmpfs testing showed that although collapse_shmem() recognizes a
concurrently truncated or hole-punched page correctly, its handling of
holes was liable to refill an emptied extent. Add check to stop that.
Link: http://lkml.kernel.org/r/alpine.LSU.2.11.1811261522040.2275@eggly.anvils
Fixes: f3f0e1d2150b2 ("khugepaged: add support of collapse for tmpfs/shmem pages")
Signed-off-by: Hugh Dickins <hughd@google.com>
Reviewed-by: Matthew Wilcox <willy@infradead.org>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
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/khugepaged.c')
| -rw-r--r-- | mm/khugepaged.c | 15 |
1 files changed, 15 insertions, 0 deletions
diff --git a/mm/khugepaged.c b/mm/khugepaged.c index a31d740e6cd1..0378f758b065 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -1350,6 +1350,16 @@ static void collapse_shmem(struct mm_struct *mm, int n = min(iter.index, end) - index; /* + * Stop if extent has been hole-punched, and is now completely + * empty (the more obvious i_size_read() check would take an + * irq-unsafe seqlock on 32-bit). + */ + if (n >= HPAGE_PMD_NR) { + result = SCAN_TRUNCATED; + goto tree_locked; + } + + /* * Handle holes in the radix tree: charge it from shmem and * insert relevant subpage of new_page into the radix-tree. */ @@ -1459,6 +1469,11 @@ out_unlock: if (result == SCAN_SUCCEED && index < end) { int n = end - index; + /* Stop if extent has been truncated, and is now empty */ + if (n >= HPAGE_PMD_NR) { + result = SCAN_TRUNCATED; + goto tree_locked; + } if (!shmem_charge(mapping->host, n)) { result = SCAN_FAIL; goto tree_locked; |