+ userfaultfd-mcopy_atomic-return-enoent-when-no-compatible-vma-found-fix.patch added to -mm tree

[akpm@linux-foundation.org]

The patch titled
     Subject: userfaultfd: mcopy_atomic: update cases returning -ENOENT
has been added to the -mm tree.  Its filename is
     userfaultfd-mcopy_atomic-return-enoent-when-no-compatible-vma-found-fix.patch

This patch should soon appear at
    http://ozlabs.org/~akpm/mmots/broken-out/userfaultfd-mcopy_atomic-return-enoent-when-no-compatible-vma-found-fix.patch
and later at
    http://ozlabs.org/~akpm/mmotm/broken-out/userfaultfd-mcopy_atomic-return-enoent-when-no-compatible-vma-found-fix.patch

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------------------------------------------------------
From: Mike Rapoport <rppt@linux.vnet.ibm.com>
Subject: userfaultfd: mcopy_atomic: update cases returning -ENOENT

As Andrea commented in [1], if the VMA covering the address was unmapped,
we may end up with a VMA a way above the faulting address. In this case we
would like to return -ENOENT to allow uffd monitor detection of VMA
removal.

[1] http://www.spinics.net/lists/linux-mm/msg121267.html

Link: http://lkml.kernel.org/r/20170207150249.GA6709@rapoport-lnx
Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
Reviewed-by: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Pavel Emelyanov <xemul@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/userfaultfd.c |   14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff -puN mm/userfaultfd.c~userfaultfd-mcopy_atomic-return-enoent-when-no-compatible-vma-found-fix mm/userfaultfd.c
--- a/mm/userfaultfd.c~userfaultfd-mcopy_atomic-return-enoent-when-no-compatible-vma-found-fix
+++ a/mm/userfaultfd.c
@@ -206,6 +206,10 @@ retry:
 		if (!dst_vma->vm_userfaultfd_ctx.ctx)
 			goto out_unlock;
 
+		if (dst_start < dst_vma->vm_start ||
+		    dst_start + len > dst_vma->vm_end)
+			goto out_unlock;
+
 		err = -EINVAL;
 		if (vma_hpagesize != vma_kernel_pagesize(dst_vma))
 			goto out_unlock;
@@ -216,9 +220,6 @@ retry:
 		 */
 		if (dst_vma->vm_flags & VM_SHARED)
 			goto out_unlock;
-		if (dst_start < dst_vma->vm_start ||
-		    dst_start + len > dst_vma->vm_end)
-			goto out_unlock;
 	}
 
 	if (WARN_ON(dst_addr & (vma_hpagesize - 1) ||
@@ -385,13 +386,14 @@ retry:
 	if (!dst_vma->vm_userfaultfd_ctx.ctx)
 		goto out_unlock;
 
-	err = -EINVAL;
-	if (!vma_is_shmem(dst_vma) && dst_vma->vm_flags & VM_SHARED)
-		goto out_unlock;
 	if (dst_start < dst_vma->vm_start ||
 	    dst_start + len > dst_vma->vm_end)
 		goto out_unlock;
 
+	err = -EINVAL;
+	if (!vma_is_shmem(dst_vma) && dst_vma->vm_flags & VM_SHARED)
+		goto out_unlock;
+
 	/*
 	 * If this is a HUGETLB vma, pass off to appropriate routine
 	 */
_

Patches currently in -mm which might be from rppt@linux.vnet.ibm.com are

userfaultfd-non-cooperative-dup_userfaultfd-use-mm_count-instead-of-mm_users.patch
userfaultfd-introduce-vma_can_userfault.patch
userfaultfd-shmem-add-shmem_mcopy_atomic_pte-for-userfaultfd-support.patch
userfaultfd-shmem-introduce-vma_is_shmem.patch
userfaultfd-shmem-use-shmem_mcopy_atomic_pte-for-shared-memory.patch
userfaultfd-shmem-add-userfaultfd-hook-for-shared-memory-faults.patch
userfaultfd-shmem-allow-registration-of-shared-memory-ranges.patch
userfaultfd-shmem-add-userfaultfd_shmem-test.patch
userfaultfd-non-cooperative-selftest-introduce-userfaultfd_open.patch
userfaultfd-non-cooperative-selftest-add-ufd-parameter-to-copy_page.patch
userfaultfd-non-cooperative-selftest-add-test-for-fork-madvdontneed-and-remap-events.patch
userfaultfd-non-cooperative-rename-event_madvdontneed-to-event_remove.patch
userfaultfd-non-cooperative-add-madvise-event-for-madv_remove-request.patch
userfaultfd-non-cooperative-selftest-enable-remove-event-test-for-shmem.patch
mm-call-vm_munmap-in-munmap-syscall-instead-of-using-open-coded-version.patch
userfaultfd-non-cooperative-add-event-for-memory-unmaps.patch
userfaultfd-non-cooperative-add-event-for-exit-notification.patch
userfaultfd-non-cooperative-add-event-for-exit-notification-fix.patch
userfaultfd-mcopy_atomic-return-enoent-when-no-compatible-vma-found.patch
userfaultfd-mcopy_atomic-return-enoent-when-no-compatible-vma-found-fix.patch
userfaultfd_copy-return-enospc-in-case-mm-has-gone.patch