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authorAndrea Arcangeli <aarcange@redhat.com>2017-03-09 16:16:28 -0800
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2017-12-20 10:07:18 +0100
commit275314e90c5e84c972be2da278cee60279e07fc7 (patch)
treef6ac70d5a798c94e64eb1a48b3b575e07cf82263 /fs/userfaultfd.c
parent9bcd15bdfb6151e0418fa9321d4dce2b2eb0cb16 (diff)
userfaultfd: shmem: __do_fault requires VM_FAULT_NOPAGE
[ Upstream commit 6bbc4a4144b1a69743022ac68dfaf6e7d993abb9 ] __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> Signed-off-by: Sasha Levin <alexander.levin@verizon.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'fs/userfaultfd.c')
-rw-r--r--fs/userfaultfd.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c
index b86054cc41db..784d667475ae 100644
--- a/fs/userfaultfd.c
+++ b/fs/userfaultfd.c
@@ -419,7 +419,7 @@ int handle_userfault(struct fault_env *fe, unsigned long reason)
* in such case.
*/
down_read(&mm->mmap_sem);
- ret = 0;
+ ret = VM_FAULT_NOPAGE;
}
}