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From: Peter Xu <peterx@redhat.com>
To: linux-mm@kvack.org, linux-kernel@vger.kernel.org
Cc: David Hildenbrand <david@redhat.com>,
	Hugh Dickins <hughd@google.com>, Maya Gokhale <gokhale2@llnl.gov>,
	Jerome Glisse <jglisse@redhat.com>,
	Pavel Emelyanov <xemul@virtuozzo.com>,
	Johannes Weiner <hannes@cmpxchg.org>,
	peterx@redhat.com, Martin Cracauer <cracauer@cons.org>,
	Matthew Wilcox <willy@infradead.org>, Shaohua Li <shli@fb.com>,
	Marty McFadden <mcfadden8@llnl.gov>,
	Andrea Arcangeli <aarcange@redhat.com>,
	Mike Kravetz <mike.kravetz@oracle.com>,
	Denis Plotnikov <dplotnikov@virtuozzo.com>,
	Mike Rapoport <rppt@linux.vnet.ibm.com>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Mel Gorman <mgorman@suse.de>,
	"Kirill A . Shutemov" <kirill@shutemov.name>,
	"Dr . David Alan Gilbert" <dgilbert@redhat.com>
Subject: [PATCH v5 02/16] mm/gup: Fix __get_user_pages() on fault retry of hugetlb
Date: Thu, 26 Sep 2019 17:38:50 +0800	[thread overview]
Message-ID: <20190926093904.5090-3-peterx@redhat.com> (raw)
In-Reply-To: <20190926093904.5090-1-peterx@redhat.com>

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>
---
 mm/gup.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/mm/gup.c b/mm/gup.c
index eddbb95dcb8f..e60d32f1674d 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -833,6 +833,16 @@ 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;
 			}
 		}
-- 
2.21.0


  parent reply	other threads:[~2019-09-26  9:39 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-26  9:38 [PATCH v5 00/16] mm: Page fault enhancements Peter Xu
2019-09-26  9:38 ` [PATCH v5 01/16] mm/gup: Rename "nonblocking" to "locked" where proper Peter Xu
2019-09-26  9:38 ` Peter Xu [this message]
2019-09-26  9:38 ` [PATCH v5 03/16] mm: Introduce fault_signal_pending() Peter Xu
2019-09-26  9:38 ` [PATCH v5 04/16] x86/mm: Use helper fault_signal_pending() Peter Xu
2019-09-26  9:38 ` [PATCH v5 05/16] arc/mm: " Peter Xu
2019-09-26  9:38 ` [PATCH v5 06/16] arm64/mm: " Peter Xu
2019-09-26  9:38 ` [PATCH v5 07/16] powerpc/mm: " Peter Xu
2019-09-26  9:38 ` [PATCH v5 08/16] sh/mm: " Peter Xu
2019-09-26  9:38 ` [PATCH v5 09/16] mm: Return faster for non-fatal signals in user mode faults Peter Xu
2019-09-26  9:38 ` [PATCH v5 10/16] userfaultfd: Don't retake mmap_sem to emulate NOPAGE Peter Xu
2019-09-26  9:38 ` [PATCH v5 11/16] mm: Introduce FAULT_FLAG_DEFAULT Peter Xu
2019-09-26  9:39 ` [PATCH v5 12/16] mm: Introduce FAULT_FLAG_INTERRUPTIBLE Peter Xu
2019-09-26  9:39 ` [PATCH v5 13/16] mm: Allow VM_FAULT_RETRY for multiple times Peter Xu
2019-09-26  9:39 ` [PATCH v5 14/16] mm/gup: " Peter Xu
2019-09-26  9:39 ` [PATCH v5 15/16] mm/gup: Allow to react to fatal signals Peter Xu
2019-09-26  9:39 ` [PATCH v5 16/16] mm/userfaultfd: Honor FAULT_FLAG_KILLABLE in fault path Peter Xu
2019-09-29  9:16   ` Peter Xu
2019-10-14  8:40 ` [PATCH v5 00/16] mm: Page fault enhancements Peter Xu

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