diff options
| author | Andrea Arcangeli <[email protected]> | 2017-02-22 15:42:46 -0800 |
|---|---|---|
| committer | Linus Torvalds <[email protected]> | 2017-02-22 16:41:28 -0800 |
| commit | 09fa5296a40d01e014b4851def20b975feb98fd5 (patch) | |
| tree | 4b937777549f85e69134d5a1af48b849f174ddb0 | |
| parent | 0594f58dbd954f7747553c041d7cbbf9b6ef1947 (diff) | |
userfaultfd: non-cooperative: wake userfaults after UFFDIO_UNREGISTER
Userfaults may still happen after the userfaultfd monitor thread
received a UFFD_EVENT_MADVDONTNEED until UFFDIO_UNREGISTER is run.
Wake any pending userfault within UFFDIO_UNREGISTER protected by the
mmap_sem for writing, so they will not be reported to userland leading
to UFFDIO_COPY returning -EINVAL (as the range was already unregistered)
and they will not hang permanently either.
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Andrea Arcangeli <[email protected]>
Cc: "Dr. David Alan Gilbert" <[email protected]>
Cc: Hillf Danton <[email protected]>
Cc: Michael Rapoport <[email protected]>
Cc: Mike Kravetz <[email protected]>
Cc: Mike Rapoport <[email protected]>
Cc: Pavel Emelyanov <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
| -rw-r--r-- | fs/userfaultfd.c | 13 |
1 files changed, 13 insertions, 0 deletions
diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c index ea9008254df4..26e1ef00b63c 100644 --- a/fs/userfaultfd.c +++ b/fs/userfaultfd.c @@ -1302,6 +1302,19 @@ static int userfaultfd_unregister(struct userfaultfd_ctx *ctx, start = vma->vm_start; vma_end = min(end, vma->vm_end); + if (userfaultfd_missing(vma)) { + /* + * Wake any concurrent pending userfault while + * we unregister, so they will not hang + * permanently and it avoids userland to call + * UFFDIO_WAKE explicitly. + */ + struct userfaultfd_wake_range range; + range.start = start; + range.len = vma_end - start; + wake_userfault(vma->vm_userfaultfd_ctx.ctx, &range); + } + new_flags = vma->vm_flags & ~(VM_UFFD_MISSING | VM_UFFD_WP); prev = vma_merge(mm, prev, start, vma_end, new_flags, vma->anon_vma, vma->vm_file, vma->vm_pgoff, |