Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754774AbbG0WCS (ORCPT ); Mon, 27 Jul 2015 18:02:18 -0400 Received: from ipmail04.adl6.internode.on.net ([150.101.137.141]:23680 "EHLO ipmail04.adl6.internode.on.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754305AbbG0WCR (ORCPT ); Mon, 27 Jul 2015 18:02:17 -0400 X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: A2D0CAByqbZVPG0mLHlbgxVUaYJVpksGmmkCAgEBAoFHTQEBAQEBAQcBAQEBQAE/hCQBAQQnExwjEAgDDgoJJQ8FJQMHGhOILdECAQsBHxmGBoUvhCQRAVEHhCwFhxaNU4dahGWBR4cvkDKBCoMrLDGBDoE+AQEB Date: Tue, 28 Jul 2015 08:01:53 +1000 From: Dave Chinner To: Stephen Smalley Cc: mstevens@fedoraproject.org, linux-kernel@vger.kernel.org, nyc@holomorphy.com, hughd@google.com, akpm@linux-foundation.org, manfred@colorfullife.com, dave@stgolabs.net, linux-mm@kvack.org, wagi@monom.org, prarit@redhat.com, torvalds@linux-foundation.org, esandeen@redhat.com, eparis@redhat.com, selinux@tycho.nsa.gov, paul@paul-moore.com, linux-security-module@vger.kernel.org Subject: Re: [PATCH v2] ipc: Use private shmem or hugetlbfs inodes for shm segments. Message-ID: <20150727220153.GI3902@dastard> References: <1437741275-5388-1-git-send-email-sds@tycho.nsa.gov> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1437741275-5388-1-git-send-email-sds@tycho.nsa.gov> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4778 Lines: 96 On Fri, Jul 24, 2015 at 08:34:35AM -0400, Stephen Smalley wrote: > The shm implementation internally uses shmem or hugetlbfs inodes > for shm segments. As these inodes are never directly exposed to > userspace and only accessed through the shm operations which are > already hooked by security modules, mark the inodes with the > S_PRIVATE flag so that inode security initialization and permission > checking is skipped. > > This was motivated by the following lockdep warning: > Jul 22 14:36:40 fc23 kernel: > ====================================================== > Jul 22 14:36:40 fc23 kernel: [ INFO: possible circular locking > dependency detected ] > Jul 22 14:36:40 fc23 kernel: 4.2.0-0.rc3.git0.1.fc24.x86_64+debug #1 > Tainted: G W > Jul 22 14:36:40 fc23 kernel: > ------------------------------------------------------- > Jul 22 14:36:40 fc23 kernel: httpd/1597 is trying to acquire lock: > Jul 22 14:36:40 fc23 kernel: (&ids->rwsem){+++++.}, at: > [] shm_close+0x34/0x130 > Jul 22 14:36:40 fc23 kernel: #012but task is already holding lock: > Jul 22 14:36:40 fc23 kernel: (&mm->mmap_sem){++++++}, at: > [] SyS_shmdt+0x4b/0x180 > Jul 22 14:36:40 fc23 kernel: #012which lock already depends on the new lock. > Jul 22 14:36:40 fc23 kernel: #012the existing dependency chain (in > reverse order) is: > Jul 22 14:36:40 fc23 kernel: #012-> #3 (&mm->mmap_sem){++++++}: > Jul 22 14:36:40 fc23 kernel: [] lock_acquire+0xc7/0x270 > Jul 22 14:36:40 fc23 kernel: [] __might_fault+0x7a/0xa0 > Jul 22 14:36:40 fc23 kernel: [] filldir+0x9e/0x130 > Jul 22 14:36:40 fc23 kernel: [] > xfs_dir2_block_getdents.isra.12+0x198/0x1c0 [xfs] > Jul 22 14:36:40 fc23 kernel: [] [....] This was send via git-send-email, which means that you've mangled the line wrapping when you pasted the stack trace into the git commit message. I strongly suggest that you trim the data/kernel part of these traces as it is unneccessary information, and it makes it harder to read. i.e the trace in the commit message should look more like: ====================================================== [ INFO: possible circular locking dependency detected ] 4.2.0-0.rc3.git0.1.fc24.x86_64+debug #1 Tainted: G W ------------------------------------------------------- httpd/1597 is trying to acquire lock: (&ids->rwsem){+++++.}, at: [] shm_close+0x34/0x130 #012but task is already holding lock: (&mm->mmap_sem){++++++}, at: [] SyS_shmdt+0x4b/0x180 #012which lock already depends on the new lock. #012the existing dependency chain (in reverse order) is: #012-> #3 (&mm->mmap_sem){++++++}: [] lock_acquire+0xc7/0x270 [] __might_fault+0x7a/0xa0 [] filldir+0x9e/0x130 [] xfs_dir2_block_getdents.isra.12+0x198/0x1c0 [xfs] [] xfs_readdir+0x1b4/0x330 [xfs] [] xfs_file_readdir+0x2b/0x30 [xfs] [] iterate_dir+0x97/0x130 [] SyS_getdents+0x91/0x120 [] entry_SYSCALL_64_fastpath+0x12/0x76 #012-> #2 (&xfs_dir_ilock_class){++++.+}: [] lock_acquire+0xc7/0x270 [] down_read_nested+0x57/0xa0 [] xfs_ilock+0x167/0x350 [xfs] [] xfs_ilock_attr_map_shared+0x38/0x50 [xfs] [] xfs_attr_get+0xbd/0x190 [xfs] [] xfs_xattr_get+0x3d/0x70 [xfs] [] generic_getxattr+0x4f/0x70 [] inode_doinit_with_dentry+0x162/0x670 [] sb_finish_set_opts+0xd9/0x230 [] selinux_set_mnt_opts+0x35c/0x660 [] superblock_doinit+0x77/0xf0 [] delayed_superblock_init+0x10/0x20 [] iterate_supers+0xb3/0x110 [] selinux_complete_init+0x2f/0x40 [] security_load_policy+0x103/0x600 [] sel_write_load+0xc1/0x750 [] __vfs_write+0x37/0x100 [] vfs_write+0xa9/0x1a0 [] SyS_write+0x58/0xd0 [] entry_SYSCALL_64_fastpath+0x12/0x76 .... Cheers, Dave. -- Dave Chinner david@fromorbit.com -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/