From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753337AbdCNCrm (ORCPT ); Mon, 13 Mar 2017 22:47:42 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:50093 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751934AbdCNCrk (ORCPT ); Mon, 13 Mar 2017 22:47:40 -0400 From: Vaibhav Jain To: Greg Kroah-Hartman Cc: Vaibhav Jain , Tejun Heo , linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, Frederic Barrat Subject: [PATCH] kernfs: Check KERNFS_HAS_RELEASE before calling kernfs_release_file() Date: Tue, 14 Mar 2017 08:17:00 +0530 X-Mailer: git-send-email 2.9.3 X-TM-AS-MML: disable x-cbid: 17031402-0008-0000-0000-0000053D2ECF X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 17031402-0009-0000-0000-00001347DA57 Message-Id: <20170314024700.6167-1-vaibhav@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2017-03-14_01:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=0 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1702020001 definitions=main-1703140020 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 --- fs/kernfs/file.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/fs/kernfs/file.c b/fs/kernfs/file.c index 8e4dc7a..ac2dfe0 100644 --- a/fs/kernfs/file.c +++ b/fs/kernfs/file.c @@ -809,7 +809,8 @@ void kernfs_drain_open_files(struct kernfs_node *kn) if (kn->flags & KERNFS_HAS_MMAP) unmap_mapping_range(inode->i_mapping, 0, 0, 1); - kernfs_release_file(kn, of); + if (kn->flags & KERNFS_HAS_RELEASE) + kernfs_release_file(kn, of); } mutex_unlock(&kernfs_open_file_mutex); -- 2.9.3