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: f3f0e1d2 ("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>
parent
86705024
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