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authorAndrea Arcangeli <aarcange@redhat.com>2017-03-10 03:16:28 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2017-03-10 04:01:09 +0300
commit6bbc4a4144b1a69743022ac68dfaf6e7d993abb9 (patch)
tree6a9eaa82d3bb88a8de32ee18320559491fea8780 /Documentation/dev-tools
parentea6200e84182989a3cce9687cf79a23ac44ec4db (diff)
downloadlinux-6bbc4a4144b1a69743022ac68dfaf6e7d993abb9.tar.xz
userfaultfd: shmem: __do_fault requires VM_FAULT_NOPAGE
__do_fault assumes vmf->page has been initialized and is valid if VM_FAULT_NOPAGE is not returned by vma->vm_ops->fault(vma, vmf). handle_userfault() in turn should return VM_FAULT_NOPAGE if it doesn't return VM_FAULT_SIGBUS or VM_FAULT_RETRY (the other two possibilities). This VM_FAULT_NOPAGE case is only invoked when signal are pending and it didn't matter for anonymous memory before. It only started to matter since shmem was introduced. hugetlbfs also takes a different path and doesn't exercise __do_fault. Link: http://lkml.kernel.org/r/20170228154201.GH5816@redhat.com Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Reported-by: Dmitry Vyukov <dvyukov@google.com> Cc: "Kirill A. Shutemov" <kirill@shutemov.name> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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