From owner-svn-src-all@freebsd.org Mon Sep 16 15:12:50 2019 Return-Path: Delivered-To: svn-src-all@mailman.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.nyi.freebsd.org (Postfix) with ESMTP id 1932D125388; Mon, 16 Sep 2019 15:12:50 +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 46X8r16tQyz3KVb; Mon, 16 Sep 2019 15:12:49 +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 CCD26221F0; Mon, 16 Sep 2019 15:12:49 +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 x8GFCnDm059215; Mon, 16 Sep 2019 15:12:49 GMT (envelope-from markj@FreeBSD.org) Received: (from markj@localhost) by repo.freebsd.org (8.15.2/8.15.2/Submit) id x8GFCn07059211; Mon, 16 Sep 2019 15:12:49 GMT (envelope-from markj@FreeBSD.org) Message-Id: <201909161512.x8GFCn07059211@repo.freebsd.org> X-Authentication-Warning: repo.freebsd.org: markj set sender to markj@FreeBSD.org using -f From: Mark Johnston Date: Mon, 16 Sep 2019 15:12:49 +0000 (UTC) To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r352410 - head/sys/vm X-SVN-Group: head X-SVN-Commit-Author: markj X-SVN-Commit-Paths: head/sys/vm X-SVN-Commit-Revision: 352410 X-SVN-Commit-Repository: base MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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: Mon, 16 Sep 2019 15:12:50 -0000 Author: markj Date: Mon Sep 16 15:12:49 2019 New Revision: 352410 URL: https://svnweb.freebsd.org/changeset/base/352410 Log: Fix a race in vm_page_dequeue_deferred_free() after r352110. This function loaded the page's queue index before setting PGA_DEQUEUE. In this window the page daemon may have deactivated the page, updating its queue index. Make the operation atomic using vm_page_pqstate_cmpset(); the page daemon will not modify the page once it observes that PGA_DEQUEUE is set. Reported and tested by: pho Reviewed by: alc, kib Sponsored by: Netflix Differential Revision: https://reviews.freebsd.org/D21639 Modified: head/sys/vm/vm_page.c head/sys/vm/vm_page.h Modified: head/sys/vm/vm_page.c ============================================================================== --- head/sys/vm/vm_page.c Mon Sep 16 15:09:31 2019 (r352409) +++ head/sys/vm/vm_page.c Mon Sep 16 15:12:49 2019 (r352410) @@ -3315,13 +3315,18 @@ vm_page_dequeue_deferred_free(vm_page_t m) KASSERT(m->ref_count == 0, ("page %p has references", m)); - if ((m->aflags & PGA_DEQUEUE) != 0) - return; - atomic_thread_fence_acq(); - if ((queue = m->queue) == PQ_NONE) - return; - vm_page_aflag_set(m, PGA_DEQUEUE); - vm_page_pqbatch_submit(m, queue); + for (;;) { + if ((m->aflags & PGA_DEQUEUE) != 0) + return; + atomic_thread_fence_acq(); + if ((queue = atomic_load_8(&m->queue)) == PQ_NONE) + return; + if (vm_page_pqstate_cmpset(m, queue, queue, PGA_DEQUEUE, + PGA_DEQUEUE)) { + vm_page_pqbatch_submit(m, queue); + break; + } + } } /* Modified: head/sys/vm/vm_page.h ============================================================================== --- head/sys/vm/vm_page.h Mon Sep 16 15:09:31 2019 (r352409) +++ head/sys/vm/vm_page.h Mon Sep 16 15:12:49 2019 (r352410) @@ -783,8 +783,6 @@ vm_page_pqstate_cmpset(vm_page_t m, uint32_t oldq, uin { uint32_t *addr, nval, oval, qsmask; - vm_page_assert_locked(m); - fflags <<= VM_PAGE_AFLAG_SHIFT; nflags <<= VM_PAGE_AFLAG_SHIFT; newq <<= VM_PAGE_QUEUE_SHIFT;