Hi Paul,
I have hit upon a circular locking dependency while doing an rmdir on a
directory inside the containers code. I believe that it is safe as no one
should be able to rmdir when a container is getting mounted.
To reproduce it, just do a rmdir inside the container.
=======================================================
[ INFO: possible circular locking dependency detected ]
2.6.23-rc1-mm2-container #1
-------------------------------------------------------
rmdir/4321 is trying to acquire lock:
(container_mutex){--..}, at: [<c03f3fe0>] mutex_lock+0x21/0x24
but task is already holding lock:
(&inode->i_mutex){--..}, at: [<c03f3fe0>] mutex_lock+0x21/0x24
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #1 (&inode->i_mutex){--..}:
[<c013bae1>] check_prev_add+0xae/0x18f
[<c013bc1c>] check_prevs_add+0x5a/0xc5
[<c013bee5>] validate_chain+0x25e/0x2cd
[<c013d892>] __lock_acquire+0x629/0x691
[<c013ddef>] lock_acquire+0x61/0x7e
[<c03f40b5>] __mutex_lock_slowpath+0xc8/0x230
[<c03f3fe0>] mutex_lock+0x21/0x24
[<c014749f>] container_get_sb+0x22c/0x283
[<c0174f02>] vfs_kern_mount+0x3a/0x73
[<c0186743>] do_new_mount+0x7e/0xdc
[<c0186d8b>] do_mount+0x178/0x191
[<c0186ff3>] sys_mount+0x66/0x9d
[<c0104cc2>] sysenter_past_esp+0x5f/0x99
[<ffffffff>] 0xffffffff
-> #0 (container_mutex){--..}:
[<c013ba5e>] check_prev_add+0x2b/0x18f
[<c013bc1c>] check_prevs_add+0x5a/0xc5
[<c013bee5>] validate_chain+0x25e/0x2cd
[<c013d892>] __lock_acquire+0x629/0x691
[<c013ddef>] lock_acquire+0x61/0x7e
[<c03f40b5>] __mutex_lock_slowpath+0xc8/0x230
[<c03f3fe0>] mutex_lock+0x21/0x24
[<c01484f3>] container_rmdir+0x15/0x163
[<c017b711>] vfs_rmdir+0x59/0x8f
[<c017b7d3>] do_rmdir+0x8c/0xbe
[<c017b815>] sys_rmdir+0x10/0x12
[<c0104cc2>] sysenter_past_esp+0x5f/0x99
[<ffffffff>] 0xffffffff
other info that might help us debug this:
2 locks held by rmdir/4321:
#0: (&inode->i_mutex/1){--..}, at: [<c017b7b3>] do_rmdir+0x6c/0xbe
#1: (&inode->i_mutex){--..}, at: [<c03f3fe0>] mutex_lock+0x21/0x24
stack backtrace:
[<c0105ad0>] show_trace_log_lvl+0x12/0x22
[<c0105aed>] show_trace+0xd/0xf
[<c0105bc3>] dump_stack+0x14/0x16
[<c013b401>] print_circular_bug_tail+0x5b/0x64
[<c013ba5e>] check_prev_add+0x2b/0x18f
[<c013bc1c>] check_prevs_add+0x5a/0xc5
[<c013bee5>] validate_chain+0x25e/0x2cd
[<c013d892>] __lock_acquire+0x629/0x691
[<c013ddef>] lock_acquire+0x61/0x7e
[<c03f40b5>] __mutex_lock_slowpath+0xc8/0x230
[<c03f3fe0>] mutex_lock+0x21/0x24
[<c01484f3>] container_rmdir+0x15/0x163
[<c017b711>] vfs_rmdir+0x59/0x8f
[<c017b7d3>] do_rmdir+0x8c/0xbe
[<c017b815>] sys_rmdir+0x10/0x12
[<c0104cc2>] sysenter_past_esp+0x5f/0x99
=======================
--
regards,
Dhaval
I would like to change the world but they don't give me the source code!
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