From owner-svn-src-all@freebsd.org Sun Feb 3 18:38:59 2019 Return-Path: Delivered-To: svn-src-all@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id DA85014AE51E; Sun, 3 Feb 2019 18:38:59 +0000 (UTC) (envelope-from markj@FreeBSD.org) Received: from mxrelay.nyi.freebsd.org (mxrelay.nyi.freebsd.org [IPv6:2610:1c1:1:606c::19:3]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) server-signature RSA-PSS (4096 bits) client-signature RSA-PSS (4096 bits) client-digest SHA256) (Client CN "mxrelay.nyi.freebsd.org", Issuer "Let's Encrypt Authority X3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 7F139813E7; Sun, 3 Feb 2019 18:38:59 +0000 (UTC) (envelope-from markj@FreeBSD.org) Received: from repo.freebsd.org (repo.freebsd.org [IPv6:2610:1c1:1:6068::e6a:0]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mxrelay.nyi.freebsd.org (Postfix) with ESMTPS id 748DE2280A; Sun, 3 Feb 2019 18:38:59 +0000 (UTC) (envelope-from markj@FreeBSD.org) Received: from repo.freebsd.org ([127.0.1.37]) by repo.freebsd.org (8.15.2/8.15.2) with ESMTP id x13Icxsd035886; Sun, 3 Feb 2019 18:38:59 GMT (envelope-from markj@FreeBSD.org) Received: (from markj@localhost) by repo.freebsd.org (8.15.2/8.15.2/Submit) id x13IcxQN035885; Sun, 3 Feb 2019 18:38:59 GMT (envelope-from markj@FreeBSD.org) Message-Id: <201902031838.x13IcxQN035885@repo.freebsd.org> X-Authentication-Warning: repo.freebsd.org: markj set sender to markj@FreeBSD.org using -f From: Mark Johnston Date: Sun, 3 Feb 2019 18:38:59 +0000 (UTC) To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r343719 - head/sys/vm X-SVN-Group: head X-SVN-Commit-Author: markj X-SVN-Commit-Paths: head/sys/vm X-SVN-Commit-Revision: 343719 X-SVN-Commit-Repository: base MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: 7F139813E7 X-Spamd-Bar: -- Authentication-Results: mx1.freebsd.org X-Spamd-Result: default: False [-2.96 / 15.00]; local_wl_from(0.00)[FreeBSD.org]; NEURAL_HAM_MEDIUM(-1.00)[-0.999,0]; NEURAL_HAM_SHORT(-0.96)[-0.959,0]; ASN(0.00)[asn:11403, ipnet:2610:1c1:1::/48, country:US]; NEURAL_HAM_LONG(-1.00)[-0.999,0] X-BeenThere: svn-src-all@freebsd.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: "SVN commit messages for the entire src tree \(except for " user" and " projects" \)" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 03 Feb 2019 18:39:00 -0000 Author: markj Date: Sun Feb 3 18:38:58 2019 New Revision: 343719 URL: https://svnweb.freebsd.org/changeset/base/343719 Log: Fix a race in vm_page_dequeue_deferred(). To detect the case where the page is already marked for a deferred dequeue, we must read the "queue" and "aflags" fields in a precise order. Otherwise, a race with a concurrent vm_page_dequeue_complete() could leave the page with PGA_DEQUEUE set despite it already having been dequeued. Fix the problem by using vm_page_queue() to check the queue state, which correctly handles the race. Reviewed by: kib Tested by: pho MFC after: 3 days Sponsored by: Netflix Differential Revision: https://reviews.freebsd.org/D19039 Modified: head/sys/vm/vm_page.c Modified: head/sys/vm/vm_page.c ============================================================================== --- head/sys/vm/vm_page.c Sun Feb 3 15:34:09 2019 (r343718) +++ head/sys/vm/vm_page.c Sun Feb 3 18:38:58 2019 (r343719) @@ -3279,18 +3279,13 @@ vm_page_dequeue_complete(vm_page_t m) void vm_page_dequeue_deferred(vm_page_t m) { - int queue; + uint8_t queue; vm_page_assert_locked(m); - queue = atomic_load_8(&m->queue); - if (queue == PQ_NONE) { - KASSERT((m->aflags & PGA_QUEUE_STATE_MASK) == 0, - ("page %p has queue state", m)); + if ((queue = vm_page_queue(m)) == PQ_NONE) return; - } - if ((m->aflags & PGA_DEQUEUE) == 0) - vm_page_aflag_set(m, PGA_DEQUEUE); + vm_page_aflag_set(m, PGA_DEQUEUE); vm_pqbatch_submit_page(m, queue); } @@ -3386,7 +3381,7 @@ vm_page_requeue(vm_page_t m) { vm_page_assert_locked(m); - KASSERT(m->queue != PQ_NONE, + KASSERT(vm_page_queue(m) != PQ_NONE, ("%s: page %p is not logically enqueued", __func__, m)); if ((m->aflags & PGA_REQUEUE) == 0)