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authorAndrea Arcangeli <aarcange@redhat.com>2017-03-09 16:16:28 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2017-03-09 17:01:09 -0800
commit6bbc4a4144b1a69743022ac68dfaf6e7d993abb9 (patch)
tree6a9eaa82d3bb88a8de32ee18320559491fea8780 /fs
parentea6200e84182989a3cce9687cf79a23ac44ec4db (diff)
downloadlinux-6bbc4a4144b1a69743022ac68dfaf6e7d993abb9.tar.bz2
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>
Diffstat (limited to 'fs')
-rw-r--r--fs/userfaultfd.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c
index 973607df579d..f62199b90fd0 100644
--- a/fs/userfaultfd.c
+++ b/fs/userfaultfd.c
@@ -490,7 +490,7 @@ int handle_userfault(struct vm_fault *vmf, unsigned long reason)
* in such case.
*/
down_read(&mm->mmap_sem);
- ret = 0;
+ ret = VM_FAULT_NOPAGE;
}
}