possible circular locking dependency detected

[Daniel Wagner]

Hi, 

I am seeing this info when I boot up my kvm guest. I think I haven't 
seen any reports on this one. In case I missed the report, sorry about
the noise.

[   92.867888] ======================================================
[   92.868440] [ INFO: possible circular locking dependency detected ]
[   92.868591] 4.0.0-rc3 #1 Not tainted
[   92.868591] -------------------------------------------------------
[   92.868591] sulogin/1617 is trying to acquire lock:
[   92.868591]  (&isec->lock){+.+.+.}, at: [<ffffffff8149e185>] inode_doinit_with_dentry+0xa5/0x680
[   92.868591] 
[   92.868591] but task is already holding lock:
[   92.868591]  (&mm->mmap_sem){++++++}, at: [<ffffffff8118635f>] vm_mmap_pgoff+0x6f/0xc0
[   92.868591] 
[   92.868591] which lock already depends on the new lock.
[   92.868591] 
[   92.868591] 
[   92.868591] the existing dependency chain (in reverse order) is:
[   92.868591] 
-> #2 (&mm->mmap_sem){++++++}:
[   92.868591]        [<ffffffff810a7ae5>] lock_acquire+0xd5/0x2a0
[   92.868591]        [<ffffffff8119879c>] might_fault+0x8c/0xb0
[   92.868591]        [<ffffffff811e6832>] filldir+0x92/0x120
[   92.868591]        [<ffffffff8138880b>] xfs_dir2_block_getdents.isra.12+0x19b/0x1f0
[   92.868591]        [<ffffffff81388994>] xfs_readdir+0x134/0x2f0
[   92.868591]        [<ffffffff8138b78b>] xfs_file_readdir+0x2b/0x30
[   92.868591]        [<ffffffff811e660a>] iterate_dir+0x9a/0x140
[   92.868591]        [<ffffffff811e6af1>] SyS_getdents+0x81/0x100
[   92.868591]        [<ffffffff81b5cfb2>] system_call_fastpath+0x12/0x17
[   92.868591] 
-> #1 (&xfs_dir_ilock_class){++++.+}:
[   92.868591]        [<ffffffff810a7ae5>] lock_acquire+0xd5/0x2a0
[   92.868591]        [<ffffffff8109feb7>] down_read_nested+0x57/0xa0
[   92.868591]        [<ffffffff8139b612>] xfs_ilock+0x92/0x290
[   92.868591]        [<ffffffff8139b888>] xfs_ilock_attr_map_shared+0x38/0x50
[   92.868591]        [<ffffffff8133c081>] xfs_attr_get+0xc1/0x180
[   92.868591]        [<ffffffff813aa9d7>] xfs_xattr_get+0x37/0x50
[   92.868591]        [<ffffffff811fb21f>] generic_getxattr+0x4f/0x70
[   92.868591]        [<ffffffff8149e232>] inode_doinit_with_dentry+0x152/0x680
[   92.868591]        [<ffffffff8149e83b>] sb_finish_set_opts+0xdb/0x260
[   92.868591]        [<ffffffff8149ec84>] selinux_set_mnt_opts+0x2c4/0x600
[   92.868591]        [<ffffffff8149f024>] superblock_doinit+0x64/0xd0
[   92.868591]        [<ffffffff8149f0a0>] delayed_superblock_init+0x10/0x20
[   92.868591]        [<ffffffff811d2d52>] iterate_supers+0xb2/0x110
[   92.868591]        [<ffffffff8149f333>] selinux_complete_init+0x33/0x40
[   92.868591]        [<ffffffff814aea46>] security_load_policy+0xf6/0x560
[   92.868591]        [<ffffffff814a0d42>] sel_write_load+0xa2/0x740
[   92.868591]        [<ffffffff811cf92a>] vfs_write+0xba/0x200
[   92.868591]        [<ffffffff811d00a9>] SyS_write+0x49/0xb0
[   92.868591]        [<ffffffff81b5cfb2>] system_call_fastpath+0x12/0x17
[   92.868591] 
-> #0 (&isec->lock){+.+.+.}:
[   92.868591]        [<ffffffff810a6a4e>] __lock_acquire+0x1ede/0x1ee0
[   92.868591]        [<ffffffff810a7ae5>] lock_acquire+0xd5/0x2a0
[   92.868591]        [<ffffffff81b588be>] mutex_lock_nested+0x6e/0x3f0
[   92.868591]        [<ffffffff8149e185>] inode_doinit_with_dentry+0xa5/0x680
[   92.868591]        [<ffffffff8149f2fc>] selinux_d_instantiate+0x1c/0x20
[   92.868591]        [<ffffffff81491b4b>] security_d_instantiate+0x1b/0x30
[   92.868591]        [<ffffffff811e9f74>] d_instantiate+0x54/0x80
[   92.868591]        [<ffffffff8118215d>] __shmem_file_setup+0xcd/0x230
[   92.868591]        [<ffffffff81185e28>] shmem_zero_setup+0x28/0x70
[   92.868591]        [<ffffffff811a2408>] mmap_region+0x5d8/0x5f0
[   92.868591]        [<ffffffff811a273b>] do_mmap_pgoff+0x31b/0x400
[   92.868591]        [<ffffffff81186380>] vm_mmap_pgoff+0x90/0xc0
[   92.868591]        [<ffffffff811a0ae6>] SyS_mmap_pgoff+0x106/0x290
[   92.868591]        [<ffffffff81008a22>] SyS_mmap+0x22/0x30
[   92.868591]        [<ffffffff81b5cfb2>] system_call_fastpath+0x12/0x17
[   92.868591] 
[   92.868591] other info that might help us debug this:
[   92.868591] 
[   92.868591] Chain exists of:
  &isec->lock --> &xfs_dir_ilock_class --> &mm->mmap_sem

[   92.868591]  Possible unsafe locking scenario:
[   92.868591] 
[   92.868591]        CPU0                    CPU1
[   92.868591]        ----                    ----
[   92.868591]   lock(&mm->mmap_sem);
[   92.868591]                                lock(&xfs_dir_ilock_class);
[   92.868591]                                lock(&mm->mmap_sem);
[   92.868591]   lock(&isec->lock);
[   92.868591] 
[   92.868591]  *** DEADLOCK ***
[   92.868591] 
[   92.868591] 1 lock held by sulogin/1617:
[   92.868591]  #0:  (&mm->mmap_sem){++++++}, at: [<ffffffff8118635f>] vm_mmap_pgoff+0x6f/0xc0
[   92.868591] 
[   92.868591] stack backtrace:
[   92.868591] CPU: 0 PID: 1617 Comm: sulogin Not tainted 4.0.0-rc3 #1
[   92.868591] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.7.5-20140709_153950- 04/01/2014
[   92.868591]  ffffffff82e6e980 ffff880078d279f8 ffffffff81b508c5 0000000000000007
[   92.868591]  ffffffff82e31af0 ffff880078d27a48 ffffffff810a30bd ffff880078fd87a0
[   92.868591]  ffff880078d27ac8 ffff880078d27a48 ffff880078fd8000 0000000000000001
[   92.868591] Call Trace:
[   92.868591]  [<ffffffff81b508c5>] dump_stack+0x4c/0x65
[   92.868591]  [<ffffffff810a30bd>] print_circular_bug+0x1cd/0x230
[   92.868591]  [<ffffffff810a6a4e>] __lock_acquire+0x1ede/0x1ee0
[   92.868591]  [<ffffffff810a0be5>] ? __bfs+0x105/0x240
[   92.868591]  [<ffffffff810a7ae5>] lock_acquire+0xd5/0x2a0
[   92.868591]  [<ffffffff8149e185>] ? inode_doinit_with_dentry+0xa5/0x680
[   92.868591]  [<ffffffff81b588be>] mutex_lock_nested+0x6e/0x3f0
[   92.868591]  [<ffffffff8149e185>] ? inode_doinit_with_dentry+0xa5/0x680
[   92.868591]  [<ffffffff811e9ef5>] ? __d_instantiate+0xd5/0x100
[   92.868591]  [<ffffffff8149e185>] ? inode_doinit_with_dentry+0xa5/0x680
[   92.868591]  [<ffffffff811e9f69>] ? d_instantiate+0x49/0x80
[   92.868591]  [<ffffffff8149e185>] inode_doinit_with_dentry+0xa5/0x680
[   92.868591]  [<ffffffff811e9f69>] ? d_instantiate+0x49/0x80
[   92.868591]  [<ffffffff8149f2fc>] selinux_d_instantiate+0x1c/0x20
[   92.868591]  [<ffffffff81491b4b>] security_d_instantiate+0x1b/0x30
[   92.868591]  [<ffffffff811e9f74>] d_instantiate+0x54/0x80
[   92.868591]  [<ffffffff8118215d>] __shmem_file_setup+0xcd/0x230
[   92.868591]  [<ffffffff81185e28>] shmem_zero_setup+0x28/0x70
[   92.868591]  [<ffffffff811a2408>] mmap_region+0x5d8/0x5f0
[   92.868591]  [<ffffffff811a273b>] do_mmap_pgoff+0x31b/0x400
[   92.868591]  [<ffffffff8118635f>] ? vm_mmap_pgoff+0x6f/0xc0
[   92.868591]  [<ffffffff81186380>] vm_mmap_pgoff+0x90/0xc0
[   92.868591]  [<ffffffff811a0ae6>] SyS_mmap_pgoff+0x106/0x290
[   92.868591]  [<ffffffff81507bfb>] ? trace_hardirqs_on_thunk+0x3a/0x3f
[   92.868591]  [<ffffffff81008a22>] SyS_mmap+0x22/0x30
[   92.868591]  [<ffffffff81b5cfb2>] system_call_fastpath+0x12/0x17


cheers,
daniel
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