The patch titled
Subject: userfaultfd: mcopy_atomic: return -ENOENT when no compatible VMA found
has been added to the -mm tree. Its filename is
userfaultfd-mcopy_atomic-return-enoent-when-no-compatible-vma-found.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/userfaultfd-mcopy_atomic-return-enoent-when-no-compatible-vma-found.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/userfaultfd-mcopy_atomic-return-enoent-when-no-compatible-vma-found.patch
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/SubmitChecklist when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Mike Rapoport <rppt@xxxxxxxxxxxxxxxxxx>
Subject: userfaultfd: mcopy_atomic: return -ENOENT when no compatible VMA found
The memory mapping of a process may change between #PF event and the call
to mcopy_atomic that comes to resolve the page fault. In such case, there
will be no VMA covering the range passed to mcopy_atomic or the VMA will
not have userfaultfd context.
To allow uffd monitor to distinguish those case from other errors, let's
return -ENOENT instead of -EINVAL.
Note, that despite availability of UFFD_EVENT_UNMAP there still might be
race between the processing of UFFD_EVENT_UNMAP and outstanding
mcopy_atomic in case of non-cooperative uffd usage.
Link: http://lkml.kernel.org/r/1485542673-24387-5-git-send-email-rppt@xxxxxxxxxxxxxxxxxx
Signed-off-by: Mike Rapoport <rppt@xxxxxxxxxxxxxxxxxx>
Acked-by: Hillf Danton <hillf.zj@xxxxxxxxxxxxxxx>
Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Cc: "Dr. David Alan Gilbert" <dgilbert@xxxxxxxxxx>
Cc: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Cc: Pavel Emelyanov <xemul@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/userfaultfd.c | 42 ++++++++++++++++++++++--------------------
1 file changed, 22 insertions(+), 20 deletions(-)
diff -puN mm/userfaultfd.c~userfaultfd-mcopy_atomic-return-enoent-when-no-compatible-vma-found mm/userfaultfd.c
--- a/mm/userfaultfd.c~userfaultfd-mcopy_atomic-return-enoent-when-no-compatible-vma-found
+++ a/mm/userfaultfd.c
@@ -195,11 +195,18 @@ retry:
* retry, dst_vma will be set to NULL and we must lookup again.
*/
if (!dst_vma) {
- err = -EINVAL;
+ err = -ENOENT;
dst_vma = find_vma(dst_mm, dst_start);
if (!dst_vma || !is_vm_hugetlb_page(dst_vma))
goto out_unlock;
+ /*
+ * Only allow __mcopy_atomic_hugetlb on userfaultfd
+ * registered ranges.
+ */
+ if (!dst_vma->vm_userfaultfd_ctx.ctx)
+ goto out_unlock;
+ err = -EINVAL;
if (vma_hpagesize != vma_kernel_pagesize(dst_vma))
goto out_unlock;
@@ -219,12 +226,6 @@ retry:
goto out_unlock;
/*
- * Only allow __mcopy_atomic_hugetlb on userfaultfd registered ranges.
- */
- if (!dst_vma->vm_userfaultfd_ctx.ctx)
- goto out_unlock;
-
- /*
* Ensure the dst_vma has a anon_vma.
*/
err = -ENOMEM;
@@ -368,10 +369,23 @@ retry:
* Make sure the vma is not shared, that the dst range is
* both valid and fully within a single existing vma.
*/
- err = -EINVAL;
+ err = -ENOENT;
dst_vma = find_vma(dst_mm, dst_start);
if (!dst_vma)
goto out_unlock;
+ /*
+ * Be strict and only allow __mcopy_atomic on userfaultfd
+ * registered ranges to prevent userland errors going
+ * unnoticed. As far as the VM consistency is concerned, it
+ * would be perfectly safe to remove this check, but there's
+ * no useful usage for __mcopy_atomic ouside of userfaultfd
+ * registered ranges. This is after all why these are ioctls
+ * belonging to the userfaultfd and not syscalls.
+ */
+ 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 ||
@@ -385,18 +399,6 @@ retry:
return __mcopy_atomic_hugetlb(dst_mm, dst_vma, dst_start,
src_start, len, zeropage);
- /*
- * Be strict and only allow __mcopy_atomic on userfaultfd
- * registered ranges to prevent userland errors going
- * unnoticed. As far as the VM consistency is concerned, it
- * would be perfectly safe to remove this check, but there's
- * no useful usage for __mcopy_atomic ouside of userfaultfd
- * registered ranges. This is after all why these are ioctls
- * belonging to the userfaultfd and not syscalls.
- */
- if (!dst_vma->vm_userfaultfd_ctx.ctx)
- goto out_unlock;
-
if (!vma_is_anonymous(dst_vma) && !vma_is_shmem(dst_vma))
goto out_unlock;
_
Patches currently in -mm which might be from rppt@xxxxxxxxxxxxxxxxxx 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-mcopy_atomic-return-enoent-when-no-compatible-vma-found.patch
userfaultfd_copy-return-enospc-in-case-mm-has-gone.patch
--
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
