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On Tue, 2006-05-30 at 21:04 +0200, Arjan van de Ven wrote: > On Tue, 2006-05-30 at 20:39 +0200, Michal Piotrowski wrote: > > Hi, > > > > On 30/05/06, Andrew Morton <akpm@osdl.org> wrote: > > > > > > ftp://ftp.kernel.org/pub/linux/kernel/people/akpm/patches/2.6/2.6.17-rc5/2.6.17-rc5-mm1/ > > > > > > > I get this on 2.6.17-rc5-mm1 + hot fixes + Arjan's net/ipv4/igmp.c patch. > > > > May 30 20:25:56 ltg01-fedora kernel: > > May 30 20:25:56 ltg01-fedora kernel: > > ===================================================== > > May 30 20:25:56 ltg01-fedora kernel: [ BUG: possible circular locking > > deadlock detected! ] > > May 30 20:25:56 ltg01-fedora kernel: > > ----------------------------------------------------- > > May 30 20:25:56 ltg01-fedora kernel: umount/2322 is trying to acquire lock: > > May 30 20:25:56 ltg01-fedora kernel: (sb_security_lock){--..}, at: > > [<c01d6400>] selinux_sb_free_security+0x17/0x4e > > > ok so selinux_complete_init() does > spin_lock(&sb_security_lock); > next_sb: > if (!list_empty(&superblock_security_head)) { > struct superblock_security_struct *sbsec = > list_entry(superblock_security_head.next, > struct superblock_security_struct, > list); > struct super_block *sb = sbsec->sb; > spin_lock(&sb_lock); > sb->s_count++; > spin_unlock(&sb_lock); > spin_unlock(&sb_security_lock); > > nesting sb_lock inside sb_security_lock > > while > > put_super() takes the sb_lock, then calls __put_super() which calls > selinux_sb_free_security which calls superblock_free_security() which takes sb_security_lock > which means the nesting is opposite. > > > textbook AB-BA deadlock Yes, looks that way, although oddly I don't see this warning myself upon performing a umount (w/ 2.6.17-rc5-mm1-lockdep). Patch below should fix. --- Fix unsafe nesting of sb_lock inside sb_security_lock in selinux_complete_init. Detected by the kernel locking validator. Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov> --- security/selinux/hooks.c | 6 ++++-- 1 files changed, 4 insertions(+), 2 deletions(-) --- linux-2.6.17-rc5-mm1/security/selinux/hooks.c 2006-05-30 14:26:11.000000000 -0400 +++ linux-2.6.17-rc5-mm1-x/security/selinux/hooks.c 2006-05-31 07:29:23.000000000 -0400 @@ -4448,6 +4448,7 @@ void selinux_complete_init(void) /* Set up any superblocks initialized prior to the policy load. */ printk(KERN_INFO "SELinux: Setting up existing superblocks.\n"); + spin_lock(&sb_lock); spin_lock(&sb_security_lock); next_sb: if (!list_empty(&superblock_security_head)) { @@ -4456,19 +4457,20 @@ next_sb: struct superblock_security_struct, list); struct super_block *sb = sbsec->sb; - spin_lock(&sb_lock); sb->s_count++; - spin_unlock(&sb_lock); spin_unlock(&sb_security_lock); + spin_unlock(&sb_lock); down_read(&sb->s_umount); if (sb->s_root) superblock_doinit(sb, NULL); drop_super(sb); + spin_lock(&sb_lock); spin_lock(&sb_security_lock); list_del_init(&sbsec->list); goto next_sb; } spin_unlock(&sb_security_lock); + spin_unlock(&sb_lock); } /* SELinux requires early initialization in order to label -- Stephen Smalley National Security Agency - 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/ | ||||||||||||
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