提交 09fa5296 编写于 作者: A Andrea Arcangeli 提交者: Linus Torvalds

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@redhat.comSigned-off-by: NAndrea Arcangeli <aarcange@redhat.com>
Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Michael Rapoport <RAPOPORT@il.ibm.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
上级 0594f58d
......@@ -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,
......
Markdown is supported
0% .
You are about to add 0 people to the discussion. Proceed with caution.
先完成此消息的编辑!
想要评论请 注册