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| author | Hugh Dickins <hughd@google.com> | 2018-06-01 16:50:45 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2018-06-02 09:33:47 -0700 |
| commit | 2d077d4b59924acd1f5180c6fb73b57f4771fde6 (patch) | |
| tree | 8d34f637439da9d593ad11e476e7e9d0bc20d893 /mm/huge_memory.c | |
| parent | dd52cb879063ca5470d5a093c32180ba74fa528e (diff) | |
| download | op-kernel-dev-2d077d4b59924acd1f5180c6fb73b57f4771fde6.zip op-kernel-dev-2d077d4b59924acd1f5180c6fb73b57f4771fde6.tar.gz | |
mm/huge_memory.c: __split_huge_page() use atomic ClearPageDirty()
Swapping load on huge=always tmpfs (with khugepaged tuned up to be very
eager, but I'm not sure that is relevant) soon hung uninterruptibly,
waiting for page lock in shmem_getpage_gfp()'s find_lock_entry(), most
often when "cp -a" was trying to write to a smallish file. Debug showed
that the page in question was not locked, and page->mapping NULL by now,
but page->index consistent with having been in a huge page before.
Reproduced in minutes on a 4.15 kernel, even with 4.17's 605ca5ede764
("mm/huge_memory.c: reorder operations in __split_huge_page_tail()") added
in; but took hours to reproduce on a 4.17 kernel (no idea why).
The culprit proved to be the __ClearPageDirty() on tails beyond i_size in
__split_huge_page(): the non-atomic __bitoperation may have been safe when
4.8's baa355fd3314 ("thp: file pages support for split_huge_page()")
introduced it, but liable to erase PageWaiters after 4.10's 62906027091f
("mm: add PageWaiters indicating tasks are waiting for a page bit").
Link: http://lkml.kernel.org/r/alpine.LSU.2.11.1805291841070.3197@eggly.anvils
Fixes: 62906027091f ("mm: add PageWaiters indicating tasks are waiting for a page bit")
Signed-off-by: Hugh Dickins <hughd@google.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Cc: Nicholas Piggin <npiggin@gmail.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/huge_memory.c')
| -rw-r--r-- | mm/huge_memory.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/mm/huge_memory.c b/mm/huge_memory.c index a3a1815..b9f3dbd 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -2431,7 +2431,7 @@ static void __split_huge_page(struct page *page, struct list_head *list, __split_huge_page_tail(head, i, lruvec, list); /* Some pages can be beyond i_size: drop them from page cache */ if (head[i].index >= end) { - __ClearPageDirty(head + i); + ClearPageDirty(head + i); __delete_from_page_cache(head + i, NULL); if (IS_ENABLED(CONFIG_SHMEM) && PageSwapBacked(head)) shmem_uncharge(head->mapping->host, 1); |
