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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>,
	Denis Plotnikov <dplotnikov@virtuozzo.com>,
	Shaohua Li <shli@fb.com>, Andrea Arcangeli <aarcange@redhat.com>,
	Mike Kravetz <mike.kravetz@oracle.com>,
	Marty McFadden <mcfadden8@llnl.gov>,
	Mike Rapoport <rppt@linux.vnet.ibm.com>,
	Mel Gorman <mgorman@suse.de>,
	"Kirill A . Shutemov" <kirill@shutemov.name>,
	"Dr . David Alan Gilbert" <dgilbert@redhat.com>
Subject: [PATCH v5 05/25] mm: gup: allow VM_FAULT_RETRY for multiple times
Date: Thu, 20 Jun 2019 10:19:48 +0800	[thread overview]
Message-ID: <20190620022008.19172-6-peterx@redhat.com> (raw)
In-Reply-To: <20190620022008.19172-1-peterx@redhat.com>

This is the gup counterpart of the change that allows the VM_FAULT_RETRY
to happen for more than once.

Reviewed-by: Jerome Glisse <jglisse@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
---
 mm/gup.c     | 17 +++++++++++++----
 mm/hugetlb.c |  6 ++++--
 2 files changed, 17 insertions(+), 6 deletions(-)

diff --git a/mm/gup.c b/mm/gup.c
index 58d282115d9b..ac8d5b73c212 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -647,7 +647,10 @@ static int faultin_page(struct task_struct *tsk, struct vm_area_struct *vma,
 	if (*flags & FOLL_NOWAIT)
 		fault_flags |= FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_RETRY_NOWAIT;
 	if (*flags & FOLL_TRIED) {
-		VM_WARN_ON_ONCE(fault_flags & FAULT_FLAG_ALLOW_RETRY);
+		/*
+		 * Note: FAULT_FLAG_ALLOW_RETRY and FAULT_FLAG_TRIED
+		 * can co-exist
+		 */
 		fault_flags |= FAULT_FLAG_TRIED;
 	}
 
@@ -1062,17 +1065,23 @@ static __always_inline long __get_user_pages_locked(struct task_struct *tsk,
 		if (likely(pages))
 			pages += ret;
 		start += ret << PAGE_SHIFT;
+		lock_dropped = true;
 
+retry:
 		/*
 		 * Repeat on the address that fired VM_FAULT_RETRY
-		 * without FAULT_FLAG_ALLOW_RETRY but with
+		 * with both FAULT_FLAG_ALLOW_RETRY and
 		 * FAULT_FLAG_TRIED.
 		 */
 		*locked = 1;
-		lock_dropped = true;
 		down_read(&mm->mmap_sem);
 		ret = __get_user_pages(tsk, mm, start, 1, flags | FOLL_TRIED,
-				       pages, NULL, NULL);
+				       pages, NULL, locked);
+		if (!*locked) {
+			/* Continue to retry until we succeeded */
+			BUG_ON(ret != 0);
+			goto retry;
+		}
 		if (ret != 1) {
 			BUG_ON(ret > 1);
 			if (!pages_done)
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index ba179c2fa8fb..d9c739f9a28e 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -4317,8 +4317,10 @@ long follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma,
 				fault_flags |= FAULT_FLAG_ALLOW_RETRY |
 					FAULT_FLAG_RETRY_NOWAIT;
 			if (flags & FOLL_TRIED) {
-				VM_WARN_ON_ONCE(fault_flags &
-						FAULT_FLAG_ALLOW_RETRY);
+				/*
+				 * Note: FAULT_FLAG_ALLOW_RETRY and
+				 * FAULT_FLAG_TRIED can co-exist
+				 */
 				fault_flags |= FAULT_FLAG_TRIED;
 			}
 			ret = hugetlb_fault(mm, vma, vaddr, fault_flags);
-- 
2.21.0


  parent reply	other threads:[~2019-06-20  2:21 UTC|newest]

Thread overview: 34+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-06-20  2:19 [PATCH v5 00/25] userfaultfd: write protection support Peter Xu
2019-06-20  2:19 ` [PATCH v5 01/25] mm: gup: rename "nonblocking" to "locked" where proper Peter Xu
2019-06-20  2:19 ` [PATCH v5 02/25] mm: userfault: return VM_FAULT_RETRY on signals Peter Xu
2019-06-22 18:02   ` Linus Torvalds
2019-06-24  7:42     ` Peter Xu
2019-06-24 13:31       ` Linus Torvalds
2019-06-25  5:30         ` Peter Xu
2019-06-26  1:59           ` Linus Torvalds
2019-06-26  7:43             ` Peter Xu
2019-06-20  2:19 ` [PATCH v5 03/25] userfaultfd: don't retake mmap_sem to emulate NOPAGE Peter Xu
2019-06-20  2:19 ` [PATCH v5 04/25] mm: allow VM_FAULT_RETRY for multiple times Peter Xu
2019-06-20  2:19 ` Peter Xu [this message]
2019-06-20  2:19 ` [PATCH v5 06/25] userfaultfd: wp: add helper for writeprotect check Peter Xu
2019-06-20  2:19 ` [PATCH v5 07/25] userfaultfd: wp: hook userfault handler to write protection fault Peter Xu
2019-06-20  2:19 ` [PATCH v5 08/25] userfaultfd: wp: add WP pagetable tracking to x86 Peter Xu
2019-06-20  2:19 ` [PATCH v5 09/25] userfaultfd: wp: userfaultfd_pte/huge_pmd_wp() helpers Peter Xu
2019-06-20  2:19 ` [PATCH v5 10/25] userfaultfd: wp: add UFFDIO_COPY_MODE_WP Peter Xu
2019-06-20  2:19 ` [PATCH v5 11/25] mm: merge parameters for change_protection() Peter Xu
2019-06-20  2:19 ` [PATCH v5 12/25] userfaultfd: wp: apply _PAGE_UFFD_WP bit Peter Xu
2019-06-20  2:19 ` [PATCH v5 13/25] userfaultfd: wp: drop _PAGE_UFFD_WP properly when fork Peter Xu
2019-06-20  2:19 ` [PATCH v5 14/25] userfaultfd: wp: add pmd_swp_*uffd_wp() helpers Peter Xu
2019-06-20  2:19 ` [PATCH v5 15/25] userfaultfd: wp: support swap and page migration Peter Xu
2019-06-20  2:19 ` [PATCH v5 16/25] khugepaged: skip collapse if uffd-wp detected Peter Xu
2019-06-20  2:20 ` [PATCH v5 17/25] userfaultfd: introduce helper vma_find_uffd Peter Xu
2019-06-20  2:20 ` [PATCH v5 18/25] userfaultfd: wp: support write protection for userfault vma range Peter Xu
2019-06-20  2:20 ` [PATCH v5 19/25] userfaultfd: wp: add the writeprotect API to userfaultfd ioctl Peter Xu
2019-06-20  2:20 ` [PATCH v5 20/25] userfaultfd: wp: enabled write protection in userfaultfd API Peter Xu
2019-06-20  2:20 ` [PATCH v5 21/25] userfaultfd: wp: don't wake up when doing write protect Peter Xu
2019-06-20  2:20 ` [PATCH v5 22/25] userfaultfd: wp: UFFDIO_REGISTER_MODE_WP documentation update Peter Xu
2019-06-20  2:20 ` [PATCH v5 23/25] userfaultfd: wp: declare _UFFDIO_WRITEPROTECT conditionally Peter Xu
2019-06-20  2:20 ` [PATCH v5 24/25] userfaultfd: selftests: refactor statistics Peter Xu
2019-06-20  2:20 ` [PATCH v5 25/25] userfaultfd: selftests: add write-protect test Peter Xu
2020-02-18  3:59 ` [PATCH v5 00/25] userfaultfd: write protection support Bobby Powers
2020-02-18 16:11   ` Peter Xu

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