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authorMike Kravetz <mike.kravetz@oracle.com>2016-01-15 16:57:40 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2016-01-15 17:56:32 -0800
commit4aae8d1c051ea00b456da6811bc36d1f69de5445 (patch)
tree6a32e3ded1783842e31aaf42d69eb2a6b663975f /mm/memory-failure.c
parent9aacdd354d197ad64685941b36d28ea20ab88757 (diff)
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mm/hugetlbfs: unmap pages if page fault raced with hole punch
Page faults can race with fallocate hole punch. If a page fault happens between the unmap and remove operations, the page is not removed and remains within the hole. This is not the desired behavior. The race is difficult to detect in user level code as even in the non-race case, a page within the hole could be faulted back in before fallocate returns. If userfaultfd is expanded to support hugetlbfs in the future, this race will be easier to observe. If this race is detected and a page is mapped, the remove operation (remove_inode_hugepages) will unmap the page before removing. The unmap within remove_inode_hugepages occurs with the hugetlb_fault_mutex held so that no other faults will be processed until the page is removed. The (unmodified) routine hugetlb_vmdelete_list was moved ahead of remove_inode_hugepages to satisfy the new reference. [akpm@linux-foundation.org: move hugetlb_vmdelete_list()] Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Hugh Dickins <hughd@google.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Dave Hansen <dave.hansen@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/memory-failure.c')
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