• Michal Hocko's avatar
    hugetlb: do not use vma_hugecache_offset() for vma_prio_tree_foreach · 36e4f20a
    Michal Hocko authored
    Commit 0c176d52 ("mm: hugetlb: fix pgoff computation when unmapping
    page from vma") fixed pgoff calculation but it has replaced it by
    vma_hugecache_offset() which is not approapriate for offsets used for
    vma_prio_tree_foreach() because that one expects index in page units
    rather than in huge_page_shift.
    
    Johannes said:
    
    : The resulting index may not be too big, but it can be too small: assume
    : hpage size of 2M and the address to unmap to be 0x200000.  This is regular
    : page index 512 and hpage index 1.  If you have a VMA that maps the file
    : only starting at the second huge page, that VMAs vm_pgoff will be 512 but
    : you ask for offset 1 and miss it even though it does map the page of
    : interest.  hugetlb_cow() will try to unmap, miss the vma, and retry the
    : cow until the allocation succeeds or the skipped vma(s) go away.
    Signed-off-by: default avatarMichal Hocko <mhocko@suse.cz>
    Acked-by: default avatarHillf Danton <dhillf@gmail.com>
    Cc: Mel Gorman <mel@csn.ul.ie>
    Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
    Cc: Andrea Arcangeli <aarcange@redhat.com>
    Cc: David Rientjes <rientjes@google.com>
    Acked-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
    Cc: <stable@vger.kernel.org>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    36e4f20a
hugetlb.c 81.8 KB