From: Aneesh Kumar K.V Date: Tue, 20 Mar 2012 23:48:19 +0000 (+1100) Subject: hugetlbfs: lockdep annotate root inode properly X-Git-Tag: next-20120402~1^2~47 X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=fb7952827e5033df1ceb000b35ea4ba00925461e;p=karo-tx-linux.git hugetlbfs: lockdep annotate root inode properly Fix the below lockdep warning: ====================================================== [ INFO: possible circular locking dependency detected ] 3.3.0-rc4+ #190 Not tainted ------------------------------------------------------- shared/1568 is trying to acquire lock: (&sb->s_type->i_mutex_key#12){+.+.+.}, at: [] hugetlbfs_file_mmap+0x7d/0x108 but task is already holding lock: (&mm->mmap_sem){++++++}, at: [] sys_mmap_pgoff+0xd4/0x12f which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (&mm->mmap_sem){++++++}: [] lock_acquire+0xd5/0xfa [] might_fault+0x6d/0x90 [] filldir+0x6a/0xc2 [] dcache_readdir+0x5c/0x222 [] vfs_readdir+0x76/0xac [] sys_getdents+0x79/0xc9 [] system_call_fastpath+0x16/0x1b -> #0 (&sb->s_type->i_mutex_key#12){+.+.+.}: [] __lock_acquire+0xa6c/0xd60 [] lock_acquire+0xd5/0xfa [] __mutex_lock_common+0x48/0x350 [] mutex_lock_nested+0x2a/0x31 [] hugetlbfs_file_mmap+0x7d/0x108 [] mmap_region+0x26f/0x466 [] do_mmap_pgoff+0x294/0x2ee [] sys_mmap_pgoff+0xf4/0x12f [] sys_mmap+0x1d/0x1f [] system_call_fastpath+0x16/0x1b other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&mm->mmap_sem); lock(&sb->s_type->i_mutex_key#12); lock(&mm->mmap_sem); lock(&sb->s_type->i_mutex_key#12); *** DEADLOCK *** 1 lock held by shared/1568: #0: (&mm->mmap_sem){++++++}, at: [] sys_mmap_pgoff+0xd4/0x12f stack backtrace: Pid: 1568, comm: shared Not tainted 3.3.0-rc4+ #190 Call Trace: [] print_circular_bug+0x1f8/0x209 [] __lock_acquire+0xa6c/0xd60 [] ? files_lglock_local_lock_cpu+0x61/0x61 [] ? hugetlbfs_file_mmap+0x7d/0x108 [] lock_acquire+0xd5/0xfa [] ? hugetlbfs_file_mmap+0x7d/0x108 Signed-off-by: Aneesh Kumar K.V Cc: Josh Boyer Cc: Dave Jones Cc: Peter Zijlstra Cc: Al Viro Cc: Mimi Zohar Signed-off-by: Andrew Morton --- diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c index ea251749d9d5..971373b142ba 100644 --- a/fs/hugetlbfs/inode.c +++ b/fs/hugetlbfs/inode.c @@ -485,6 +485,7 @@ static struct inode *hugetlbfs_get_root(struct super_block *sb, inode->i_fop = &simple_dir_operations; /* directory inodes start off with i_nlink == 2 (for "." entry) */ inc_nlink(inode); + lockdep_annotate_inode_mutex_key(inode); } return inode; }