From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Morton Subject: [patch 087/155] mm/gup: fix __get_user_pages() on fault retry of hugetlb Date: Wed, 01 Apr 2020 21:08:02 -0700 Message-ID: <20200402040802.XNDU2drzz%akpm@linux-foundation.org> References: <20200401210155.09e3b9742e1c6e732f5a7250@linux-foundation.org> Reply-To: linux-kernel@vger.kernel.org Return-path: Received: from mail.kernel.org ([198.145.29.99]:59462 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726205AbgDBEIE (ORCPT ); Thu, 2 Apr 2020 00:08:04 -0400 In-Reply-To: <20200401210155.09e3b9742e1c6e732f5a7250@linux-foundation.org> Sender: mm-commits-owner@vger.kernel.org List-Id: mm-commits@vger.kernel.org To: aarcange@redhat.com, akpm@linux-foundation.org, bgeffon@google.com, bobbypowers@gmail.com, cracauer@cons.org, david@redhat.com, dgilbert@redhat.com, dplotnikov@virtuozzo.com, gokhale2@llnl.gov, hannes@cmpxchg.org, hughd@google.com, jglisse@redhat.com, kirill@shutemov.name, linux-mm@kvack.org, mcfadden8@llnl.gov, mgorman@suse.de, mike.kravetz@oracle.com, mm-commits@vger.kernel.org, peterx@redhat.com, rppt@linux.vnet.ibm.com, torvalds@linux-foundation.org, willy@infradead.org, xemul@openvz.org From: Peter Xu Subject: 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. Link: http://lkml.kernel.org/r/20200220155353.8676-3-peterx@redhat.com Signed-off-by: Peter Xu Tested-by: Brian Geffon Cc: Andrea Arcangeli Cc: Bobby Powers Cc: David Hildenbrand Cc: Denis Plotnikov Cc: "Dr . David Alan Gilbert" Cc: Hugh Dickins Cc: Jerome Glisse Cc: Johannes Weiner Cc: "Kirill A . Shutemov" Cc: Linus Torvalds Cc: Martin Cracauer Cc: Marty McFadden Cc: Matthew Wilcox Cc: Maya Gokhale Cc: Mel Gorman Cc: Mike Kravetz Cc: Mike Rapoport Cc: Pavel Emelyanov Signed-off-by: Andrew Morton --- mm/gup.c | 10 ++++++++++ 1 file changed, 10 insertions(+) --- a/mm/gup.c~mm-gup-fix-__get_user_pages-on-fault-retry-of-hugetlb +++ a/mm/gup.c @@ -1065,6 +1065,16 @@ static long __get_user_pages(struct task 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; } } _