Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753902AbdCPVOH (ORCPT ); Thu, 16 Mar 2017 17:14:07 -0400 Received: from mail-yw0-f196.google.com ([209.85.161.196]:36669 "EHLO mail-yw0-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753757AbdCPVOD (ORCPT ); Thu, 16 Mar 2017 17:14:03 -0400 Date: Thu, 16 Mar 2017 17:13:29 -0400 From: Tejun Heo To: Vaibhav Jain Cc: Greg Kroah-Hartman , linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, Frederic Barrat Subject: Re: [PATCH] kernfs: Check KERNFS_HAS_RELEASE before calling kernfs_release_file() Message-ID: <20170316211329.GB1480@htj.duckdns.org> References: <20170314024700.6167-1-vaibhav@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170314024700.6167-1-vaibhav@linux.vnet.ibm.com> User-Agent: Mutt/1.7.1 (2016-10-04) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2609 Lines: 52 On Tue, Mar 14, 2017 at 08:17:00AM +0530, Vaibhav Jain wrote: > Recently started seeing a kernel oops when a module tries removing a > memory mapped sysfs bin_attribute. On closer investigation the root > cause seems to be kernfs_release_file() trying to call > kernfs_op.release() callback that's NULL for such sysfs > bin_attributes. The oops occurs when kernfs_release_file() is called from > kernfs_drain_open_files() to cleanup any open handles with active > memory mappings. > > The patch fixes this by checking for flag KERNFS_HAS_RELEASE before > calling kernfs_release_file() in function kernfs_drain_open_files(). > > On ppc64-le arch with cxl module the oops back-trace is of the > form below: > [ 861.381126] Unable to handle kernel paging request for instruction fetch > [ 861.381360] Faulting instruction address: 0x00000000 > [ 861.381428] Oops: Kernel access of bad area, sig: 11 [#1] > .... > [ 861.382481] NIP: 0000000000000000 LR: c000000000362c60 CTR: > 0000000000000000 > .... > Call Trace: > [c000000f1680b750] [c000000000362c34] kernfs_drain_open_files+0x104/0x1d0 (unreliable) > [c000000f1680b790] [c00000000035fa00] __kernfs_remove+0x260/0x2c0 > [c000000f1680b820] [c000000000360da0] kernfs_remove_by_name_ns+0x60/0xe0 > [c000000f1680b8b0] [c0000000003638f4] sysfs_remove_bin_file+0x24/0x40 > [c000000f1680b8d0] [c00000000062a164] device_remove_bin_file+0x24/0x40 > [c000000f1680b8f0] [d000000009b7b22c] cxl_sysfs_afu_remove+0x144/0x170 [cxl] > [c000000f1680b940] [d000000009b7c7e4] cxl_remove+0x6c/0x1a0 [cxl] > [c000000f1680b990] [c00000000052f694] pci_device_remove+0x64/0x110 > [c000000f1680b9d0] [c0000000006321d4] device_release_driver_internal+0x1f4/0x2b0 > [c000000f1680ba20] [c000000000525cb0] pci_stop_bus_device+0xa0/0xd0 > [c000000f1680ba60] [c000000000525e80] pci_stop_and_remove_bus_device+0x20/0x40 > [c000000f1680ba90] [c00000000004a6c4] pci_hp_remove_devices+0x84/0xc0 > [c000000f1680bad0] [c00000000004a688] pci_hp_remove_devices+0x48/0xc0 > [c000000f1680bb10] [c0000000009dfda4] eeh_reset_device+0xb0/0x290 > [c000000f1680bbb0] [c000000000032b4c] eeh_handle_normal_event+0x47c/0x530 > [c000000f1680bc60] [c000000000032e64] eeh_handle_event+0x174/0x350 > [c000000f1680bd10] [c000000000033228] eeh_event_handler+0x1e8/0x1f0 > [c000000f1680bdc0] [c0000000000d384c] kthread+0x14c/0x190 > [c000000f1680be30] [c00000000000b5a0] ret_from_kernel_thread+0x5c/0xbc > > Fixes: f83f3c515654("kernfs: fix locking around kernfs_ops->release() > callback") > Signed-off-by: Vaibhav Jain Acked-by: Tejun Heo Thanks. -- tejun