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>
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@ -301,8 +301,23 @@ retry:
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out_unlock:
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up_read(&dst_mm->mmap_sem);
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out:
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if (page)
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if (page) {
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/*
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* We encountered an error and are about to free a newly
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* allocated huge page. It is possible that there was a
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* reservation associated with the page that has been
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* consumed. See the routine restore_reserve_on_error
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* for details. Unfortunately, we can not call
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* restore_reserve_on_error now as it would require holding
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* mmap_sem. Clear the PagePrivate flag so that the global
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* reserve count will not be incremented in free_huge_page.
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* The reservation map will still indicate the reservation
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* was consumed and possibly prevent later page allocation.
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* This is better than leaking a global reservation.
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*/
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ClearPagePrivate(page);
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put_page(page);
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}
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BUG_ON(copied < 0);
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BUG_ON(err > 0);
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BUG_ON(!copied && !err);
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