diff options
| author | Hugh Dickins <hughd@google.com> | 2018-11-30 14:10:25 -0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-12-05 19:42:36 +0100 |
| commit | 10e458e6eb59e533e499269258b6069392bec627 (patch) | |
| tree | 46f631347aa89aca1112963eb04571d92adff421 /mm/khugepaged.c | |
| parent | b59b24fed59d322718a3f0fcaacf492335e9c9ca (diff) | |
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 1df37ee996d5..62de24194f24 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -1352,6 +1352,16 @@ 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. */ @@ -1462,6 +1472,11 @@ 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; |