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| author | Mike Kravetz <mike.kravetz@oracle.com> | 2017-02-22 15:43:16 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2017-02-22 16:41:28 -0800 |
| commit | 21205bf8f77b23484966cb057ceaec860cc400b3 (patch) | |
| tree | f7d5a23cf21e316e370ebe1a7ed704b8c9b078da /mm/userfaultfd.c | |
| parent | 87ffc118b54dcd4cc642723603d944673248152f (diff) | |
| download | linux-21205bf8f77b23484966cb057ceaec860cc400b3.tar.bz2 | |
userfaultfd: hugetlbfs: reserve count on error in __mcopy_atomic_hugetlb
If __mcopy_atomic_hugetlb exits with an error, put_page will be called
if a huge page was allocated and needs to be freed. If a reservation
was associated with the huge page, the PagePrivate flag will be set.
Clear PagePrivate before calling put_page/free_huge_page so that the
global reservation count is not incremented.
Link: http://lkml.kernel.org/r/20161216144821.5183-26-aarcange@redhat.com
Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
Signed-off-by: Andrea 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 Rapoport <rppt@linux.vnet.ibm.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/userfaultfd.c')
| -rw-r--r-- | mm/userfaultfd.c | 17 |
1 files changed, 16 insertions, 1 deletions
diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c index 09976745be23..31207b47ea92 100644 --- a/mm/userfaultfd.c +++ b/mm/userfaultfd.c @@ -301,8 +301,23 @@ retry: out_unlock: up_read(&dst_mm->mmap_sem); out: - if (page) + if (page) { + /* + * We encountered an error and are about to free a newly + * allocated huge page. It is possible that there was a + * reservation associated with the page that has been + * consumed. See the routine restore_reserve_on_error + * for details. Unfortunately, we can not call + * restore_reserve_on_error now as it would require holding + * mmap_sem. Clear the PagePrivate flag so that the global + * reserve count will not be incremented in free_huge_page. + * The reservation map will still indicate the reservation + * was consumed and possibly prevent later page allocation. + * This is better than leaking a global reservation. + */ + ClearPagePrivate(page); put_page(page); + } BUG_ON(copied < 0); BUG_ON(err > 0); BUG_ON(!copied && !err); |