Commit ad415db8 authored by Peter Xu's avatar Peter Xu Committed by Linus Torvalds
Browse files

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: default avatarPeter Xu <peterx@redhat.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Tested-by: default avatarBrian 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: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 4f6da934

mm/gup.c

+10 −0
Original line number Diff line number Diff line
@@ -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;

			}

		}