The patch titled
Subject: userfaultfd: non-cooperative: avoid MADV_DONTNEED race condition
has been added to the -mm tree. Its filename is
userfaultfd-non-cooperative-avoid-madv_dontneed-race-condition.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/userfaultfd-non-cooperative-avoid-madv_dontneed-race-condition.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/userfaultfd-non-cooperative-avoid-madv_dontneed-race-condition.patch
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*** Remember to use Documentation/SubmitChecklist when testing your code ***
The -mm tree is included into linux-next and is updated
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------------------------------------------------------
From: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Subject: userfaultfd: non-cooperative: avoid MADV_DONTNEED race condition
MADV_DONTNEED must be notified to userland before the pages are zapped.
This allows userland to immediately stop adding pages to the userfaultfd
ranges before the pages are actually zapped or there could be non-zeropage
leftovers as result of concurrent UFFDIO_COPY run in between
zap_page_range and madvise_userfault_dontneed (both MADV_DONTNEED and
UFFDIO_COPY runs under the mmap_sem for reading, so they can run
concurrently).
Link: http://lkml.kernel.org/r/20161216144821.5183-15-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>
---
mm/madvise.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff -puN mm/madvise.c~userfaultfd-non-cooperative-avoid-madv_dontneed-race-condition mm/madvise.c
--- a/mm/madvise.c~userfaultfd-non-cooperative-avoid-madv_dontneed-race-condition
+++ a/mm/madvise.c
@@ -477,8 +477,8 @@ static long madvise_dontneed(struct vm_a
if (vma->vm_flags & (VM_LOCKED|VM_HUGETLB|VM_PFNMAP))
return -EINVAL;
- zap_page_range(vma, start, end - start, NULL);
madvise_userfault_dontneed(vma, prev, start, end);
+ zap_page_range(vma, start, end - start, NULL);
return 0;
}
_
Patches currently in -mm which might be from aarcange@xxxxxxxxxx are
userfaultfd-document-_ior-_iow.patch
userfaultfd-correct-comment-about-uffd_feature_pagefault_flag_wp.patch
userfaultfd-convert-bug-to-warn_on_once.patch
userfaultfd-use-vma_is_anonymous.patch
userfaultfd-non-cooperative-report-all-available-features-to-userland.patch
userfaultfd-non-cooperative-add-fork-event-build-warning-fix.patch
userfaultfd-non-cooperative-optimize-mremap_userfaultfd_complete.patch
userfaultfd-non-cooperative-avoid-madv_dontneed-race-condition.patch
userfaultfd-non-cooperative-wake-userfaults-after-uffdio_unregister.patch
userfaultfd-hugetlbfs-gup-support-vm_fault_retry.patch
userfaultfd-hugetlbfs-uffd_feature_missing_hugetlbfs.patch
userfaultfd-shmem-add-tlbflushh-header-for-microblaze.patch
userfaultfd-shmem-lock-the-page-before-adding-it-to-pagecache.patch
userfaultfd-shmem-avoid-leaking-blocks-and-used-blocks-in-uffdio_copy.patch
userfaultfd-hugetlbfs-uffd_feature_missing_shmem.patch
userfaultfd-selftest-test-uffdio_zeropage-on-all-memory-types.patch
mm-mprotect-use-pmd_trans_unstable-instead-of-taking-the-pmd_lock.patch
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