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| author | Liu Yuntao <liuyuntao10@huawei.com> | 2021-09-25 01:43:32 +0300 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2021-09-25 02:13:34 +0300 |
| commit | de6ee659684b1a2b149e0780d3c5e8032f3647d6 (patch) | |
| tree | 0a7c7ffc5aecd0e884e79404de81b1fbc87cfd70 /mm | |
| parent | 867050247e295cf20fce046a92a7e6491fcfe066 (diff) | |
| download | linux-de6ee659684b1a2b149e0780d3c5e8032f3647d6.tar.xz | |
mm/shmem.c: fix judgment error in shmem_is_huge()
In the case of SHMEM_HUGE_WITHIN_SIZE, the page index is not rounded up
correctly. When the page index points to the first page in a huge page,
round_up() cannot bring it to the end of the huge page, but to the end
of the previous one.
An example:
HPAGE_PMD_NR on my machine is 512(2 MB huge page size). After
allcoating a 3000 KB buffer, I access it at location 2050 KB. In
shmem_is_huge(), the corresponding index happens to be 512. After
rounded up by HPAGE_PMD_NR, it will still be 512 which is smaller than
i_size, and shmem_is_huge() will return true. As a result, my buffer
takes an additional huge page, and that shouldn't happen when
shmem_enabled is set to within_size.
Link: https://lkml.kernel.org/r/20210909032007.18353-1-liuyuntao10@huawei.com
Fixes: f3f0e1d2150b2b ("khugepaged: add support of collapse for tmpfs/shmem pages")
Signed-off-by: Liu Yuntao <liuyuntao10@huawei.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Hugh Dickins <hughd@google.com>
Cc: wuxu.wu <wuxu.wu@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/shmem.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/mm/shmem.c b/mm/shmem.c index 88742953532c..b5860f4a2738 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -490,9 +490,9 @@ bool shmem_is_huge(struct vm_area_struct *vma, case SHMEM_HUGE_ALWAYS: return true; case SHMEM_HUGE_WITHIN_SIZE: - index = round_up(index, HPAGE_PMD_NR); + index = round_up(index + 1, HPAGE_PMD_NR); i_size = round_up(i_size_read(inode), PAGE_SIZE); - if (i_size >= HPAGE_PMD_SIZE && (i_size >> PAGE_SHIFT) >= index) + if (i_size >> PAGE_SHIFT >= index) return true; fallthrough; case SHMEM_HUGE_ADVISE: |