Messages in this thread | | | Date | Mon, 7 Dec 2009 12:59:50 +0100 | From | Andi Kleen <> | Subject | NFS lockdep lock misordering mmap_sem<->i_mutex_key with 2.6.32-git1 |
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While booting 2.6.32-git1 on a NFS root box I got the following lockdep warning early at boot. I haven't looked at details.
-Andi
VFS: Mounted root (nfs filesystem) on device 0:15. VFS: Mounted root (nfs filesystem) on device 0:15. Freeing unused kernel memory: 2376k freed
======================================================= [ INFO: possible circular locking dependency detected ] ------------------------------------------------------- udevinfo/2551 is trying to acquire lock: (&sb->s_type->i_mutex_key#5){+.+.+.}, at: [<ffffffff8118e0d3>] nfs_revalidate_mapping+0x7c/0xc5
but task is already holding lock: (&mm->mmap_sem){++++++}, at: [<ffffffff8100fc83>] sys_mmap+0x76/0xc7
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #1 (&mm->mmap_sem){++++++}: [<ffffffff81071d0b>] __lock_acquire+0x1435/0x1774 [<ffffffff81072106>] lock_acquire+0xbc/0xd9 [<ffffffff810baa14>] might_fault+0x84/0xa4 [<ffffffff810ec340>] filldir+0x6a/0xcb [<ffffffff81189bad>] nfs_do_filldir+0x39d/0x4ac [<ffffffff8118a4e9>] nfs_readdir+0x82d/0x8ce [<ffffffff810ec4bf>] vfs_readdir+0x6c/0xa1 [<ffffffff810ec632>] sys_getdents+0x7d/0xc9 [<ffffffff8100ba6b>] system_call_fastpath+0x16/0x1b
-> #0 (&sb->s_type->i_mutex_key#5){+.+.+.}: [<ffffffff81071a30>] __lock_acquire+0x115a/0x1774 [<ffffffff81072106>] lock_acquire+0xbc/0xd9 [<ffffffff8149210d>] mutex_lock_nested+0x68/0x2d2 [<ffffffff8118e0d3>] nfs_revalidate_mapping+0x7c/0xc5 [<ffffffff8118bad9>] nfs_file_mmap+0x68/0x71 [<ffffffff810c29c0>] mmap_region+0x311/0x50f [<ffffffff810c2f13>] do_mmap_pgoff+0x355/0x3b8 [<ffffffff8100fca1>] sys_mmap+0x94/0xc7 [<ffffffff8100ba6b>] system_call_fastpath+0x16/0x1b
other info that might help us debug this:
1 lock held by udevinfo/2551: #0: (&mm->mmap_sem){++++++}, at: [<ffffffff8100fc83>] sys_mmap+0x76/0xc7
stack backtrace: Pid: 2551, comm: udevinfo Not tainted 2.6.32-git1 #31 Call Trace: [<ffffffff81070388>] print_circular_bug+0xb3/0xc2 [<ffffffff81071a30>] __lock_acquire+0x115a/0x1774 [<ffffffff810a401d>] ? find_get_pages_tag+0x0/0x12a [<ffffffff81072106>] lock_acquire+0xbc/0xd9 [<ffffffff8118e0d3>] ? nfs_revalidate_mapping+0x7c/0xc5 [<ffffffff8149210d>] mutex_lock_nested+0x68/0x2d2 [<ffffffff8118e0d3>] ? nfs_revalidate_mapping+0x7c/0xc5 [<ffffffff8118e0d3>] ? nfs_revalidate_mapping+0x7c/0xc5 [<ffffffff810c291d>] ? mmap_region+0x26e/0x50f [<ffffffff8118e0d3>] nfs_revalidate_mapping+0x7c/0xc5 [<ffffffff8118bad9>] nfs_file_mmap+0x68/0x71 [<ffffffff810c29c0>] mmap_region+0x311/0x50f [<ffffffff810c2f13>] do_mmap_pgoff+0x355/0x3b8 [<ffffffff8100fca1>] sys_mmap+0x94/0xc7 [<ffffffff8100ba6b>] system_call_fastpath+0x16/0x1b
-Andi -- ak@linux.intel.com -- Speaking for myself only.
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