From patchwork Thu Dec 5 09:55:55 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Jon Medhurst (Tixy)" X-Patchwork-Id: 3287111 Return-Path: X-Original-To: patchwork-linux-arm@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.19.201]) by patchwork2.web.kernel.org (Postfix) with ESMTP id 10C31C0D4A for ; Thu, 5 Dec 2013 09:57:47 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id CE080204EB for ; Thu, 5 Dec 2013 09:57:45 +0000 (UTC) Received: from casper.infradead.org (casper.infradead.org [85.118.1.10]) (using TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 13B322041D for ; Thu, 5 Dec 2013 09:57:44 +0000 (UTC) Received: from merlin.infradead.org ([2001:4978:20e::2]) by casper.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1VoVfj-00077I-DR; Thu, 05 Dec 2013 09:56:39 +0000 Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1VoVfR-0004av-Te; Thu, 05 Dec 2013 09:56:21 +0000 Received: from smarthost01c.mail.zen.net.uk ([212.23.1.5]) by merlin.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1VoVfO-0004Z3-1b for linux-arm-kernel@lists.infradead.org; Thu, 05 Dec 2013 09:56:18 +0000 Received: from [82.69.122.217] (helo=[192.168.2.110]) by smarthost01c.mail.zen.net.uk with esmtpsa (TLS1.0:DHE_RSA_CAMELLIA_256_CBC_SHA1:256) (Exim 4.80) (envelope-from ) id 1VoVf1-0006CM-Li; Thu, 05 Dec 2013 09:55:55 +0000 Message-ID: <1386237355.16677.34.camel@linaro1.home> Subject: Re: [GIT PULL] Cacheflush updates for 3.12 From: "Jon Medhurst (Tixy)" To: Will Deacon Date: Thu, 05 Dec 2013 09:55:55 +0000 In-Reply-To: <20131204161329.GA14145@mudshark.cambridge.arm.com> References: <20130812173155.GI25995@mudshark.cambridge.arm.com> <20131204161329.GA14145@mudshark.cambridge.arm.com> X-Mailer: Evolution 3.4.4-3 Mime-Version: 1.0 X-Originating-smarthost01c-IP: [82.69.122.217] X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20131205_045618_178095_BC1B7919 X-CRM114-Status: GOOD ( 33.79 ) X-Spam-Score: -1.2 (-) Cc: Christian Gmeiner , "linux-arm-kernel@lists.infradead.org" X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Spam-Status: No, score=-4.2 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_MED, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP On Wed, 2013-12-04 at 16:13 +0000, Will Deacon wrote: > On Wed, Dec 04, 2013 at 03:37:36PM +0000, Christian Gmeiner wrote: > > 2013/8/12 Will Deacon : > > > Please pull the following user-cacheflush updates for 3.12. This series both > > > improves performance of cacheflush-heavy workloads (i.e. browser benchmarks) > > > and also addresses a DoS issue on non-preemptible systems. > > [...] > > > Hi all. > > Hello, > > > I spend the last day running a bisect and I think I have found a problem :) > > > > I have a simple automated test case running, which looks like this: > > > > imx6d based device running X, chromium and x11vnc <----> windows pc connected > > via VNC to the device. With this patchset applyed the browser tab > > crashed after about > > 5 minutes hitting the F5/refresh button every 1-3 seconds. > > Hmm... it would be great if we had a simpler way to reproduce this, but ok. > How many cores do you have on your IMX6? Also, how does the browser tab crash? > Does it receive a SIGILL? I think I'm also seeing this problem with Linaro Android on vexpress. The latest Android version (KitKat) has moved to using the Chrome browser and it crashes very easily after just a few seconds use (with SIGSEGV's because execution jumped into kernel virtual memory range). The reason I think it's the same issue as talked about in this email is that after reading this I check a 3.10 kernel with the same Android image and that was fine. Then I tried a previously crashing 3.13-rc2 kernel with the hack below to undo $subject, and that stopped the crashes: A Linaro Android vexpress build which shows the bug can de found at https://android-build.linaro.org/builds/~linaro-android/vexpress-linaro/#build=172 And the bug is being tracked at https://bugs.launchpad.net/linaro-android/+bug/1254750 (ignore comments on that report about serial console issues, they should have been on a different bug report) diff --git a/arch/arm/kernel/traps.c b/arch/arm/kernel/traps.c index dbf0923..ff58932 100644 --- a/arch/arm/kernel/traps.c +++ b/arch/arm/kernel/traps.c @@ -560,7 +560,7 @@ do_cache_op(unsigned long start, unsigned long end, int flags) if (!access_ok(VERIFY_READ, start, end - start)) return -EFAULT; - return __do_cache_op(start, end); + return flush_cache_user_range(start, end); }