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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>,
	Shaohua Li <shli@fb.com>, Andrea Arcangeli <aarcange@redhat.com>,
	Mike Kravetz <mike.kravetz@oracle.com>,
	Denis Plotnikov <dplotnikov@virtuozzo.com>,
	Mike Rapoport <rppt@linux.vnet.ibm.com>,
	Marty McFadden <mcfadden8@llnl.gov>, Mel Gorman <mgorman@suse.de>,
	"Kirill A . Shutemov" <kirill@shutemov.name>,
	"Dr . David Alan Gilbert" <dgilbert@redhat.com>
Subject: [PATCH v3 23/28] userfaultfd: wp: don't wake up when doing write protect
Date: Wed, 20 Mar 2019 10:06:37 +0800	[thread overview]
Message-ID: <20190320020642.4000-24-peterx@redhat.com> (raw)
In-Reply-To: <20190320020642.4000-1-peterx@redhat.com>

It does not make sense to try to wake up any waiting thread when we're
write-protecting a memory region.  Only wake up when resolving a write
protected page fault.

Reviewed-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
---
 fs/userfaultfd.c | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c
index 81962d62520c..f1f61a0278c2 100644
--- a/fs/userfaultfd.c
+++ b/fs/userfaultfd.c
@@ -1771,6 +1771,7 @@ static int userfaultfd_writeprotect(struct userfaultfd_ctx *ctx,
 	struct uffdio_writeprotect uffdio_wp;
 	struct uffdio_writeprotect __user *user_uffdio_wp;
 	struct userfaultfd_wake_range range;
+	bool mode_wp, mode_dontwake;
 
 	if (READ_ONCE(ctx->mmap_changing))
 		return -EAGAIN;
@@ -1789,18 +1790,20 @@ static int userfaultfd_writeprotect(struct userfaultfd_ctx *ctx,
 	if (uffdio_wp.mode & ~(UFFDIO_WRITEPROTECT_MODE_DONTWAKE |
 			       UFFDIO_WRITEPROTECT_MODE_WP))
 		return -EINVAL;
-	if ((uffdio_wp.mode & UFFDIO_WRITEPROTECT_MODE_WP) &&
-	     (uffdio_wp.mode & UFFDIO_WRITEPROTECT_MODE_DONTWAKE))
+
+	mode_wp = uffdio_wp.mode & UFFDIO_WRITEPROTECT_MODE_WP;
+	mode_dontwake = uffdio_wp.mode & UFFDIO_WRITEPROTECT_MODE_DONTWAKE;
+
+	if (mode_wp && mode_dontwake)
 		return -EINVAL;
 
 	ret = mwriteprotect_range(ctx->mm, uffdio_wp.range.start,
-				  uffdio_wp.range.len, uffdio_wp.mode &
-				  UFFDIO_WRITEPROTECT_MODE_WP,
+				  uffdio_wp.range.len, mode_wp,
 				  &ctx->mmap_changing);
 	if (ret)
 		return ret;
 
-	if (!(uffdio_wp.mode & UFFDIO_WRITEPROTECT_MODE_DONTWAKE)) {
+	if (!mode_wp && !mode_dontwake) {
 		range.start = uffdio_wp.range.start;
 		range.len = uffdio_wp.range.len;
 		wake_userfault(ctx, &range);
-- 
2.17.1


  parent reply	other threads:[~2019-03-20  2:10 UTC|newest]

Thread overview: 51+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-03-20  2:06 [PATCH v3 00/28] userfaultfd: write protection support Peter Xu
2019-03-20  2:06 ` [PATCH v3 01/28] mm: gup: rename "nonblocking" to "locked" where proper Peter Xu
2019-03-20  2:06 ` [PATCH v3 02/28] mm: userfault: return VM_FAULT_RETRY on signals Peter Xu
2019-03-20  2:06 ` [PATCH v3 03/28] userfaultfd: don't retake mmap_sem to emulate NOPAGE Peter Xu
2019-03-20  2:06 ` [PATCH v3 04/28] mm: allow VM_FAULT_RETRY for multiple times Peter Xu
2019-04-18 20:11   ` Jerome Glisse
2019-04-19  6:00     ` Peter Xu
2019-03-20  2:06 ` [PATCH v3 05/28] mm: gup: " Peter Xu
2019-03-20  2:06 ` [PATCH v3 06/28] userfaultfd: wp: add helper for writeprotect check Peter Xu
2019-03-20  2:06 ` [PATCH v3 07/28] userfaultfd: wp: hook userfault handler to write protection fault Peter Xu
2019-04-18 20:03   ` Jerome Glisse
2019-03-20  2:06 ` [PATCH v3 08/28] userfaultfd: wp: add WP pagetable tracking to x86 Peter Xu
2019-03-20  2:06 ` [PATCH v3 09/28] userfaultfd: wp: userfaultfd_pte/huge_pmd_wp() helpers Peter Xu
2019-03-20  2:06 ` [PATCH v3 10/28] userfaultfd: wp: add UFFDIO_COPY_MODE_WP Peter Xu
2019-03-20  2:06 ` [PATCH v3 11/28] mm: merge parameters for change_protection() Peter Xu
2019-03-20  2:06 ` [PATCH v3 12/28] userfaultfd: wp: apply _PAGE_UFFD_WP bit Peter Xu
2019-03-20  2:06 ` [PATCH v3 13/28] mm: export wp_page_copy() Peter Xu
2019-03-20  2:06 ` [PATCH v3 14/28] userfaultfd: wp: handle COW properly for uffd-wp Peter Xu
2019-04-18 20:51   ` Jerome Glisse
2019-04-19  6:26     ` Peter Xu
2019-04-19 15:02       ` Jerome Glisse
2019-04-22 12:20         ` Peter Xu
2019-04-22 14:54           ` Jerome Glisse
2019-04-23  3:00             ` Peter Xu
2019-04-23 15:34               ` Jerome Glisse
2019-04-24  8:38                 ` Peter Xu
2019-03-20  2:06 ` [PATCH v3 15/28] userfaultfd: wp: drop _PAGE_UFFD_WP properly when fork Peter Xu
2019-03-20  2:06 ` [PATCH v3 16/28] userfaultfd: wp: add pmd_swp_*uffd_wp() helpers Peter Xu
2019-03-20  2:06 ` [PATCH v3 17/28] userfaultfd: wp: support swap and page migration Peter Xu
2019-04-18 20:59   ` Jerome Glisse
2019-04-19  7:42     ` Peter Xu
2019-04-19 15:08       ` Jerome Glisse
2019-04-22 12:23         ` Peter Xu
2019-03-20  2:06 ` [PATCH v3 18/28] khugepaged: skip collapse if uffd-wp detected Peter Xu
2019-03-20  2:06 ` [PATCH v3 19/28] userfaultfd: introduce helper vma_find_uffd Peter Xu
2019-03-20  2:06 ` [PATCH v3 20/28] userfaultfd: wp: support write protection for userfault vma range Peter Xu
2019-03-20  2:06 ` [PATCH v3 21/28] userfaultfd: wp: add the writeprotect API to userfaultfd ioctl Peter Xu
2019-03-20  2:06 ` [PATCH v3 22/28] userfaultfd: wp: enabled write protection in userfaultfd API Peter Xu
2019-03-22 21:37   ` Mike Rapoport
2019-03-20  2:06 ` Peter Xu [this message]
2019-03-20  2:06 ` [PATCH v3 24/28] userfaultfd: wp: UFFDIO_REGISTER_MODE_WP documentation update Peter Xu
2019-03-22 21:46   ` Mike Rapoport
2019-03-20  2:06 ` [PATCH v3 25/28] userfaultfd: wp: fixup swap entries in change_pte_range Peter Xu
2019-04-18 21:01   ` Jerome Glisse
2019-03-20  2:06 ` [PATCH v3 26/28] userfaultfd: wp: declare _UFFDIO_WRITEPROTECT conditionally Peter Xu
2019-03-22 21:43   ` Mike Rapoport
2019-03-20  2:06 ` [PATCH v3 27/28] userfaultfd: selftests: refactor statistics Peter Xu
2019-03-20  2:06 ` [PATCH v3 28/28] userfaultfd: selftests: add write-protect test Peter Xu
2019-04-09  6:08 ` [PATCH v3 00/28] userfaultfd: write protection support Peter Xu
2019-04-18 21:07   ` Jerome Glisse
2019-04-19  7:53     ` Peter Xu

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