From ba611edfe406be745be95c332990c8e908c026c3 Mon Sep 17 00:00:00 2001 From: Joonwoo Park Date: Wed, 26 Dec 2007 12:09:57 +0900 Subject: [PATCH] configfs: dir.c fix possible recursive locking configfs_register_subsystem() with default_groups triggers recursive locking. it seems that mutex_lock_nested is needed. ============================================= [ INFO: possible recursive locking detected ] 2.6.24-rc6 #141 --------------------------------------------- swapper/1 is trying to acquire lock: (&sb->s_type->i_mutex_key#3){--..}, at: [] configfs_attach_group+0x4f/0x190 but task is already holding lock: (&sb->s_type->i_mutex_key#3){--..}, at: [] configfs_register_subsystem+0x55/0x130 other info that might help us debug this: 1 lock held by swapper/1: #0: (&sb->s_type->i_mutex_key#3){--..}, at: [] configfs_register_subsystem+0x55/0x130 stack backtrace: Pid: 1, comm: swapper Not tainted 2.6.24-rc6 #141 [] show_trace_log_lvl+0x1a/0x30 [] show_trace+0x12/0x20 [] dump_stack+0x6e/0x80 [] __lock_acquire+0xe62/0x1120 [] lock_acquire+0x82/0xa0 [] mutex_lock_nested+0x98/0x2e0 [] configfs_attach_group+0x4f/0x190 [] configfs_register_subsystem+0xc6/0x130 [] init_netconsole+0x2b6/0x300 [] kernel_init+0x142/0x320 [] kernel_thread_helper+0x7/0x14 ======================= Signed-off-by: Joonwoo Park Signed-off-by: Joel Becker Signed-off-by: Mark Fasheh --- fs/configfs/dir.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/fs/configfs/dir.c b/fs/configfs/dir.c index 50ed691..a48dc7d 100644 --- a/fs/configfs/dir.c +++ b/fs/configfs/dir.c @@ -546,7 +546,7 @@ static int populate_groups(struct config_group *group) * That said, taking our i_mutex is closer to mkdir * emulation, and shouldn't hurt. */ - mutex_lock(&dentry->d_inode->i_mutex); + mutex_lock_nested(&dentry->d_inode->i_mutex, I_MUTEX_CHILD); for (i = 0; group->default_groups[i]; i++) { new_group = group->default_groups[i]; @@ -1405,7 +1405,8 @@ int configfs_register_subsystem(struct configfs_subsystem *subsys) sd = configfs_sb->s_root->d_fsdata; link_group(to_config_group(sd->s_element), group); - mutex_lock(&configfs_sb->s_root->d_inode->i_mutex); + mutex_lock_nested(&configfs_sb->s_root->d_inode->i_mutex, + I_MUTEX_PARENT); name.name = group->cg_item.ci_name; name.len = strlen(name.name); -- 2.7.4