From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752713AbdCBNFl (ORCPT ); Thu, 2 Mar 2017 08:05:41 -0500 Received: from mx2.suse.de ([195.135.220.15]:43369 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752580AbdCBNFj (ORCPT ); Thu, 2 Mar 2017 08:05:39 -0500 Subject: Re: BUG due to "xen-netback: protect resource cleaning on XenBus disconnect" To: Wei Liu References: <75c81731-e4a7-bde1-c4fd-a52e97b820a0@suse.com> <20170302120653.dce2mehbmhyxsiow@citrix.com> Cc: igor.druzhinin@citrix.com, xen-devel , Linux Kernel Mailing List , "netdev@vger.kernel.org" , Boris Ostrovsky , David Miller , Paul Durrant From: Juergen Gross Message-ID: <0e503a09-fbbb-02aa-152b-e4eaf3122a56@suse.com> Date: Thu, 2 Mar 2017 13:12:45 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.7.0 MIME-Version: 1.0 In-Reply-To: <20170302120653.dce2mehbmhyxsiow@citrix.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 02/03/17 13:06, Wei Liu wrote: > On Thu, Mar 02, 2017 at 12:56:20PM +0100, Juergen Gross wrote: >> With commits f16f1df65 and 9a6cdf52b we get in our Xen testing: >> >> [ 174.512861] switch: port 2(vif3.0) entered disabled state >> [ 174.522735] BUG: sleeping function called from invalid context at >> /home/build/linux-linus/mm/vmalloc.c:1441 >> [ 174.523451] in_atomic(): 1, irqs_disabled(): 0, pid: 28, name: xenwatch >> [ 174.524131] CPU: 1 PID: 28 Comm: xenwatch Tainted: G W >> 4.10.0upstream-11073-g4977ab6-dirty #1 >> [ 174.524819] Hardware name: MSI MS-7680/H61M-P23 (MS-7680), BIOS V17.0 >> 03/14/2011 >> [ 174.525517] Call Trace: >> [ 174.526217] show_stack+0x23/0x60 >> [ 174.526899] dump_stack+0x5b/0x88 >> [ 174.527562] ___might_sleep+0xde/0x130 >> [ 174.528208] __might_sleep+0x35/0xa0 >> [ 174.528840] ? _raw_spin_unlock_irqrestore+0x13/0x20 >> [ 174.529463] ? __wake_up+0x40/0x50 >> [ 174.530089] remove_vm_area+0x20/0x90 >> [ 174.530724] __vunmap+0x1d/0xc0 >> [ 174.531346] ? delete_object_full+0x13/0x20 >> [ 174.531973] vfree+0x40/0x80 >> [ 174.532594] set_backend_state+0x18a/0xa90 >> [ 174.533221] ? dwc_scan_descriptors+0x24d/0x430 >> [ 174.533850] ? kfree+0x5b/0xc0 >> [ 174.534476] ? xenbus_read+0x3d/0x50 >> [ 174.535101] ? xenbus_read+0x3d/0x50 >> [ 174.535718] ? xenbus_gather+0x31/0x90 >> [ 174.536332] ? ___might_sleep+0xf6/0x130 >> [ 174.536945] frontend_changed+0x6b/0xd0 >> [ 174.537565] xenbus_otherend_changed+0x7d/0x80 >> [ 174.538185] frontend_changed+0x12/0x20 >> [ 174.538803] xenwatch_thread+0x74/0x110 >> [ 174.539417] ? woken_wake_function+0x20/0x20 >> [ 174.540049] kthread+0xe5/0x120 >> [ 174.540663] ? xenbus_printf+0x50/0x50 >> [ 174.541278] ? __kthread_init_worker+0x40/0x40 >> [ 174.541898] ret_from_fork+0x21/0x2c >> [ 174.548635] switch: port 2(vif3.0) entered disabled state >> >> I believe calling vfree() when holding a spin_lock isn't a good idea. >> > > Use vfree_atomic instead? Hmm, isn't this overkill here? You can just set a local variable with the address and do vfree() after releasing the lock. Juergen