From owner-svn-src-head@freebsd.org Thu May 17 18:08:00 2018 Return-Path: Delivered-To: svn-src-head@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 524A2EDBBE2; Thu, 17 May 2018 18:08:00 +0000 (UTC) (envelope-from markjdb@gmail.com) Received: from mail-pf0-x230.google.com (mail-pf0-x230.google.com [IPv6:2607:f8b0:400e:c00::230]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority G2" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id CABF86DAA9; Thu, 17 May 2018 18:07:59 +0000 (UTC) (envelope-from markjdb@gmail.com) Received: by mail-pf0-x230.google.com with SMTP id j20-v6so2465282pff.10; Thu, 17 May 2018 11:07:59 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=sender:date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=uzVcNdjwSfboij7a8hh4bMVNEJcVz6lyJL9z2mib1Wg=; b=qDEZfroCE0b9+TlRuCwCJxLV97RVP68agWwZYNiLa11Ga1roPBH2GsG9TUu585pJ9z 9KvsATLgniZjVKV4rv+i4+sQXDvhaMMaXU4oeCmJccbCLTbgkzjYFG2HM6TTy/yVzbtE k+PW3xxzxn4EIMYp/ZsMbPNbaPADAyfOpzKfuCBk1Lw4vAKq+6pLZeyoH2QiZUBYRXoh ak7tGo4CCJIrwEgB5jPQKz3dUjtGISoD+zz81/eZxXnaGS5RmY2WqAgtoYiAsSjqg/vy CdIoImCAyuPcRLmKnPCDiAGoPPbyBDhPJaP+nHHKmlnZoxWWVQ0h5ZzSdfd03M9i0KTG Jcag== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:date:from:to:cc:subject:message-id :references:mime-version:content-disposition:in-reply-to:user-agent; bh=uzVcNdjwSfboij7a8hh4bMVNEJcVz6lyJL9z2mib1Wg=; b=E2WC6PFZlZog2ESfkuPLxWcrw51WW/hHHIbI28cFdzolwYTgnZ+3VcIezeJvwaGTKb UuwrrdAQUWegRodhqXpPfa2bt0G3Ubt7/Riw2br2tsCbZRpz4Z5MM1aTxmdHaUceZv6R vLzLj70n4CaCmVCLwozylf9Z8hXe7jgfzddWczV/3mpJaXN+fbG3cEBjUlP1vl9VzpZw qoNQgCjduopUBuF2kvem3BuJVgOcLTXoSeiDOCTc2+/CMQWBIxJi2N3x2NpMvMB78/O1 +mI6Ri3zSzj3EJcAFDFInQxPL+pwdJFnS3oMctdKb0gIjyuO+hWza8evDYpHPyAVqmmT E9vA== X-Gm-Message-State: ALKqPweYo/6st7M8d2+aE0YY15UL3o5EgfmaGteIIi+EdjXD+C8hdgqO JN1ZLb28rf18kY1YMRsneFWNbTP9 X-Google-Smtp-Source: AB8JxZqya6QJCmPbKeVGr3tKSRXW7Y3Ze65dvZA2fXaJbwfBidLKAeIRSwBpZmW6yq2I1iw2PSCC1Q== X-Received: by 2002:a63:6407:: with SMTP id y7-v6mr4706562pgb.373.1526580478500; Thu, 17 May 2018 11:07:58 -0700 (PDT) Received: from raichu (toroon0560w-lp140-02-70-49-169-130.dsl.bell.ca. [70.49.169.130]) by smtp.gmail.com with ESMTPSA id m9-v6sm9927777pff.41.2018.05.17.11.07.57 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 17 May 2018 11:07:57 -0700 (PDT) Sender: Mark Johnston Date: Thu, 17 May 2018 14:07:52 -0400 From: Mark Johnston To: Conrad Meyer Cc: src-committers , svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: Re: svn commit: r333703 - head/sys/vm Message-ID: <20180517180752.GA5515@raichu> References: <201805170427.w4H4R8lv058775@repo.freebsd.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.9.5 (2018-04-13) X-BeenThere: svn-src-head@freebsd.org X-Mailman-Version: 2.1.26 Precedence: list List-Id: SVN commit messages for the src tree for head/-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 17 May 2018 18:08:00 -0000 On Thu, May 17, 2018 at 10:07:34AM -0700, Conrad Meyer wrote: > On Wed, May 16, 2018 at 9:27 PM, Mark Johnston wrote: > > Author: markj > > Date: Thu May 17 04:27:08 2018 > > New Revision: 333703 > > URL: https://svnweb.freebsd.org/changeset/base/333703 > > > > Log: > > Fix a race in vm_page_pagequeue_lockptr(). > > > > The value of m->queue must be cached after comparing it with PQ_NONE, > > since it may be concurrently changing. > > > > Reported by: glebius > > What were the symptoms of this issue? The test plan in the linked > phabricator revision says: > > "Gleb reported seeing panics as a result of the use of a bogus index > into the pagequeue array, and also reported that this patch fixed the > panics." > > So an attempt to lock pagequeues[PQ_NONE=255].pq_mutex, which is > either something later in the vm_domain object, or bogus memory? One > of the mtx asserts trips? I think it was "mtx_lock() of spin mutex"; I didn't get a lot of details. I failed to note in the commit message that this race was introduced in r332974.