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authorPeter Xu <peterx@redhat.com>2020-04-01 21:08:02 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2020-04-02 09:35:29 -0700
commitad415db817964e96df824e8bb1a861527f8012b6 (patch)
tree5abd261ea2673311680dccb73bfd6da3d17746b5 /mm/gup.c
parent4f6da93411806db2f3e58193b31b95e8c6737616 (diff)
mm/gup: fix __get_user_pages() on fault retry of hugetlb
When follow_hugetlb_page() returns with *locked==0, it means we've got a VM_FAULT_RETRY within the fauling process and we've released the mmap_sem. When that happens, we should stop and bail out. Signed-off-by: Peter Xu <peterx@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Tested-by: Brian Geffon <bgeffon@google.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Bobby Powers <bobbypowers@gmail.com> Cc: David Hildenbrand <david@redhat.com> Cc: Denis Plotnikov <dplotnikov@virtuozzo.com> Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jerome Glisse <jglisse@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: "Kirill A . Shutemov" <kirill@shutemov.name> Cc: Martin Cracauer <cracauer@cons.org> Cc: Marty McFadden <mcfadden8@llnl.gov> Cc: Matthew Wilcox <willy@infradead.org> Cc: Maya Gokhale <gokhale2@llnl.gov> Cc: Mel Gorman <mgorman@suse.de> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Pavel Emelyanov <xemul@openvz.org> Link: http://lkml.kernel.org/r/20200220155353.8676-3-peterx@redhat.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/gup.c')
-rw-r--r--mm/gup.c10
1 files changed, 10 insertions, 0 deletions
diff --git a/mm/gup.c b/mm/gup.c
index 7e7f0054d628..4ae1a9b6a968 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -1065,6 +1065,16 @@ static long __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
i = follow_hugetlb_page(mm, vma, pages, vmas,
&start, &nr_pages, i,
gup_flags, locked);
+ if (locked && *locked == 0) {
+ /*
+ * We've got a VM_FAULT_RETRY
+ * and we've lost mmap_sem.
+ * We must stop here.
+ */
+ BUG_ON(gup_flags & FOLL_NOWAIT);
+ BUG_ON(ret != 0);
+ goto out;
+ }
continue;
}
}