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From: Peter Xu <peterx@redhat.com>
To: linux-mm@kvack.org, linux-kernel@vger.kernel.org
Cc: Hugh Dickins <hughd@google.com>, Maya Gokhale <gokhale2@llnl.gov>,
	Jerome Glisse <jglisse@redhat.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>,
	Pavel Emelyanov <xemul@parallels.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 RFC 20/24] userfaultfd: wp: don't wake up when doing write protect
Date: Mon, 21 Jan 2019 15:57:18 +0800	[thread overview]
Message-ID: <20190121075722.7945-21-peterx@redhat.com> (raw)
In-Reply-To: <20190121075722.7945-1-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.

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 455b87c0596f..e54ab6076e13 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;
 
 	user_uffdio_wp = (struct uffdio_writeprotect __user *) arg;
 
@@ -1786,17 +1787,19 @@ 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);
 	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:[~2019-01-21  8:00 UTC|newest]

Thread overview: 65+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-01-21  7:56 [PATCH RFC 00/24] userfaultfd: write protection support Peter Xu
2019-01-21  7:56 ` [PATCH RFC 01/24] mm: gup: rename "nonblocking" to "locked" where proper Peter Xu
2019-01-21 10:20   ` Mike Rapoport
2019-01-21  7:57 ` [PATCH RFC 02/24] mm: userfault: return VM_FAULT_RETRY on signals Peter Xu
2019-01-21 15:40   ` Jerome Glisse
2019-01-22  6:10     ` Peter Xu
2019-01-21  7:57 ` [PATCH RFC 03/24] mm: allow VM_FAULT_RETRY for multiple times Peter Xu
2019-01-21 15:55   ` Jerome Glisse
2019-01-22  8:22     ` Peter Xu
2019-01-22 16:53       ` Jerome Glisse
2019-01-23  2:12         ` Peter Xu
2019-01-23  2:39           ` Jerome Glisse
2019-01-24  5:45             ` Peter Xu
2019-01-21  7:57 ` [PATCH RFC 04/24] mm: gup: " Peter Xu
2019-01-21 16:24   ` Jerome Glisse
2019-01-24  7:05     ` Peter Xu
2019-01-24 15:34       ` Jerome Glisse
2019-01-25  2:49         ` Peter Xu
2019-01-21  7:57 ` [PATCH RFC 05/24] userfaultfd: wp: add helper for writeprotect check Peter Xu
2019-01-21 10:23   ` Mike Rapoport
2019-01-22  8:31     ` Peter Xu
2019-01-21  7:57 ` [PATCH RFC 06/24] userfaultfd: wp: support write protection for userfault vma range Peter Xu
2019-01-21 10:20   ` Mike Rapoport
2019-01-22  8:55     ` Peter Xu
2019-01-21 14:05   ` Jerome Glisse
2019-01-22  9:39     ` Peter Xu
2019-01-22 17:02       ` Jerome Glisse
2019-01-23  2:17         ` Peter Xu
2019-01-23  2:43           ` Jerome Glisse
2019-01-24  5:47             ` Peter Xu
2019-01-21  7:57 ` [PATCH RFC 07/24] userfaultfd: wp: add the writeprotect API to userfaultfd ioctl Peter Xu
2019-01-21 10:42   ` Mike Rapoport
2019-01-24  4:56     ` Peter Xu
2019-01-24  7:27       ` Mike Rapoport
2019-01-24  9:28         ` Peter Xu
2019-01-25  7:54           ` Mike Rapoport
2019-01-25 10:12             ` Peter Xu
2019-01-21  7:57 ` [PATCH RFC 08/24] userfaultfd: wp: hook userfault handler to write protection fault Peter Xu
2019-01-21  7:57 ` [PATCH RFC 09/24] userfaultfd: wp: enabled write protection in userfaultfd API Peter Xu
2019-01-21  7:57 ` [PATCH RFC 10/24] userfaultfd: wp: add WP pagetable tracking to x86 Peter Xu
2019-01-21 15:09   ` Jerome Glisse
2019-01-24  5:16     ` Peter Xu
2019-01-24 15:40       ` Jerome Glisse
2019-01-25  3:30         ` Peter Xu
2019-01-21  7:57 ` [PATCH RFC 11/24] userfaultfd: wp: userfaultfd_pte/huge_pmd_wp() helpers Peter Xu
2019-01-21  7:57 ` [PATCH RFC 12/24] userfaultfd: wp: add UFFDIO_COPY_MODE_WP Peter Xu
2019-01-21  7:57 ` [PATCH RFC 13/24] mm: merge parameters for change_protection() Peter Xu
2019-01-21 13:54   ` Jerome Glisse
2019-01-24  5:22     ` Peter Xu
2019-01-21  7:57 ` [PATCH RFC 14/24] userfaultfd: wp: apply _PAGE_UFFD_WP bit Peter Xu
2019-01-21  7:57 ` [PATCH RFC 15/24] mm: export wp_page_copy() Peter Xu
2019-01-21  7:57 ` [PATCH RFC 16/24] userfaultfd: wp: handle COW properly for uffd-wp Peter Xu
2019-01-21  7:57 ` [PATCH RFC 17/24] userfaultfd: wp: drop _PAGE_UFFD_WP properly when fork Peter Xu
2019-01-21  7:57 ` [PATCH RFC 18/24] userfaultfd: wp: add pmd_swp_*uffd_wp() helpers Peter Xu
2019-01-21  7:57 ` [PATCH RFC 19/24] userfaultfd: wp: support swap and page migration Peter Xu
2019-01-21  7:57 ` Peter Xu [this message]
2019-01-21 11:10   ` [PATCH RFC 20/24] userfaultfd: wp: don't wake up when doing write protect Mike Rapoport
2019-01-24  5:36     ` Peter Xu
2019-01-21  7:57 ` [PATCH RFC 21/24] khugepaged: skip collapse if uffd-wp detected Peter Xu
2019-01-21  7:57 ` [PATCH RFC 22/24] userfaultfd: wp: UFFDIO_REGISTER_MODE_WP documentation update Peter Xu
2019-01-21  7:57 ` [PATCH RFC 23/24] userfaultfd: selftests: refactor statistics Peter Xu
2019-01-21  7:57 ` [PATCH RFC 24/24] userfaultfd: selftests: add write-protect test Peter Xu
2019-01-21 14:33 ` [PATCH RFC 00/24] userfaultfd: write protection support David Hildenbrand
2019-01-22  3:18   ` Peter Xu
2019-01-22  8:59     ` David Hildenbrand

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