[patch 060/142] userfaultfd: non-cooperative: wake userfaults after UFFDIO_UNREGISTER

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



From: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Subject: 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/20161216144821.5183-16-aarcange@xxxxxxxxxx
Signed-off-by: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Cc: "Dr. David Alan Gilbert" <dgilbert@xxxxxxxxxx>
Cc: Hillf Danton <hillf.zj@xxxxxxxxxxxxxxx>
Cc: Michael Rapoport <RAPOPORT@xxxxxxxxxx>
Cc: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Cc: Mike Rapoport <rppt@xxxxxxxxxxxxxxxxxx>
Cc: Pavel Emelyanov <xemul@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---

 fs/userfaultfd.c |   13 +++++++++++++
 1 file changed, 13 insertions(+)

diff -puN fs/userfaultfd.c~userfaultfd-non-cooperative-wake-userfaults-after-uffdio_unregister fs/userfaultfd.c
--- a/fs/userfaultfd.c~userfaultfd-non-cooperative-wake-userfaults-after-uffdio_unregister
+++ a/fs/userfaultfd.c
@@ -1302,6 +1302,19 @@ static int userfaultfd_unregister(struct
 			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,
_
--
To unsubscribe from this list: send the line "unsubscribe mm-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html



[Index of Archives]     [Kernel Archive]     [IETF Annouce]     [DCCP]     [Netdev]     [Networking]     [Security]     [Bugtraq]     [Yosemite]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux RAID]     [Linux SCSI]

  Powered by Linux