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05 April 2024, 19:05:47 UTC
Revision 6bbc4a4144b1a69743022ac68dfaf6e7d993abb9 authored by Andrea Arcangeli on 10 March 2017, 00:16:28 UTC, committed by Linus Torvalds on 10 March 2017, 01:01:09 UTC 
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>
1 parent ea6200e
History
Tip revision: 6bbc4a4144b1a69743022ac68dfaf6e7d993abb9 authored by Andrea Arcangeli on 10 March 2017, 00:16:28 UTC
userfaultfd: shmem: __do_fault requires VM_FAULT_NOPAGE
Tip revision: 6bbc4a4
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