linux-kernel - Re: [PATCH 0/4] kill-the-bkl/reiserfs: fix some lock dependency inversions

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Date:	Thu, 27 Aug 2009 00:13:30 +0400
From:	Alexander Beregalov <a.beregalov@...il.com>
To:	Frederic Weisbecker <fweisbec@...il.com>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Reiserfs <reiserfs-devel@...r.kernel.org>
Subject: Re: [PATCH 0/4] kill-the-bkl/reiserfs: fix some lock dependency
	inversions

On Tue, Aug 25, 2009 at 04:32:46AM +0200, Frederic Weisbecker wrote:
> Hi,
> 
> This small set fixes some lock dependency inversions found in reiserfs
> xattr and mmap paths.
> I guess there are still some of them that I'll have to hunt, especially one
> reported by Laurent Riffard and another one introduced by the reiserfs_readdir
> path optimization (though I'm not sure about the latter, I have yet to find a
> way to reproduce it properly).
> 
> As usual, these patches can be found at:
> 
> git://git.kernel.org/pub/scm/linux/kernel/git/frederic/random-tracing.git \
> 	reiserfs/kill-bkl

Hi,
possible circular locking dependency detected

Is it false positive?

REISERFS (device sda1): found reiserfs format "3.6" with standard journal
REISERFS (device sda1): using ordered data mode
REISERFS (device sda1): journal params: device sda1, size 8192, journal first block 18, max trans len 1024, max batch 900, max commit age 30, max trans age 30
REISERFS (device sda1): checking transaction log (sda1)
REISERFS debug (device sda1): journal-1153: found in header: first_unflushed_offset 6766, last_flushed_trans_id 1836992
REISERFS debug (device sda1): journal-1206: Starting replay from offset 7889824857987694, trans_id 18
REISERFS debug (device sda1): journal-1299: Setting newest_mount_id to 229
REISERFS (device sda1): Using r5 hash to sort names
VFS: Mounted root (reiserfs filesystem) readonly on device 8:1.

=======================================================
[ INFO: possible circular locking dependency detected ]
2.6.31-rc7-00135-g9399a4c #5
-------------------------------------------------------
init.sh/599 is trying to acquire lock:
 (&mm->mmap_sem){++++++}, at: [<c1071056>] might_fault+0x46/0xa0

but task is already holding lock:
 (&REISERFS_SB(s)->lock){+.+.+.}, at: [<c10ff20e>] reiserfs_write_lock+0x1e/0x30

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&REISERFS_SB(s)->lock){+.+.+.}:
       [<c104dd18>] __lock_acquire+0xd28/0x1390
       [<c104e3ef>] lock_acquire+0x6f/0x90
       [<c133af96>] __mutex_lock_common+0x46/0x310
       [<c133b318>] mutex_lock_nested+0x38/0x40
       [<c10ff1ce>] reiserfs_write_lock_once+0x1e/0x40
       [<c10db74c>] reiserfs_get_block+0x5c/0x1440
       [<c10ae7a0>] do_mpage_readpage+0x120/0x4b0
       [<c10aec2f>] mpage_readpages+0x9f/0xe0
       [<c10d8c39>] reiserfs_readpages+0x19/0x20
       [<c10671f5>] __do_page_cache_readahead+0x195/0x210
       [<c1067291>] ra_submit+0x21/0x30
       [<c1061229>] filemap_fault+0x2e9/0x380
       [<c1072f08>] __do_fault+0x38/0x3b0
       [<c1073b5d>] handle_mm_fault+0xcd/0x550
       [<c101ad63>] do_page_fault+0xf3/0x240
       [<c133cd53>] error_code+0x63/0x68
       [<c10baa74>] padzero+0x24/0x40
       [<c10bc062>] load_elf_binary+0x632/0x1480
       [<c108aafa>] search_binary_handler+0x8a/0x270
       [<c108cb15>] do_execve+0x215/0x2a0
       [<c1001658>] sys_execve+0x28/0x60
       [<c1002d99>] syscall_call+0x7/0xb
       [<ffffffff>] 0xffffffff

-> #0 (&mm->mmap_sem){++++++}:
       [<c104dd99>] __lock_acquire+0xda9/0x1390
       [<c104e3ef>] lock_acquire+0x6f/0x90
       [<c1071087>] might_fault+0x77/0xa0
       [<c11c1886>] copy_to_user+0x36/0x130
       [<c1093c29>] filldir64+0xa9/0xf0
       [<c10deda1>] reiserfs_readdir_dentry+0x4a1/0x7b0
       [<c10df0c7>] reiserfs_readdir+0x17/0x20
       [<c1093eb5>] vfs_readdir+0x85/0xa0
       [<c1093f34>] sys_getdents64+0x64/0xb0
       [<c1002d18>] sysenter_do_call+0x12/0x36
       [<ffffffff>] 0xffffffff

other info that might help us debug this:

2 locks held by init.sh/599:
 #0:  (&sb->s_type->i_mutex_key#4){+.+.+.}, at: [<c1093e82>] vfs_readdir+0x52/0xa0
 #1:  (&REISERFS_SB(s)->lock){+.+.+.}, at: [<c10ff20e>] reiserfs_write_lock+0x1e/0x30

stack backtrace:
Pid: 599, comm: init.sh Not tainted 2.6.31-rc7-00135-g9399a4c #5
Call Trace:
 [<c133a11a>] ? printk+0x18/0x1e
 [<c104bfdd>] print_circular_bug_tail+0x8d/0xd0
 [<c104dd99>] __lock_acquire+0xda9/0x1390
 [<c104e3ef>] lock_acquire+0x6f/0x90
 [<c1071056>] ? might_fault+0x46/0xa0
 [<c1071087>] might_fault+0x77/0xa0
 [<c1071056>] ? might_fault+0x46/0xa0
 [<c11c1886>] copy_to_user+0x36/0x130
 [<c1093c29>] filldir64+0xa9/0xf0
 [<c10ff20e>] ? reiserfs_write_lock+0x1e/0x30
 [<c10deda1>] reiserfs_readdir_dentry+0x4a1/0x7b0
 [<c1093b80>] ? filldir64+0x0/0xf0
 [<c104d453>] ? __lock_acquire+0x463/0x1390
 [<c104c62e>] ? trace_hardirqs_on_caller+0x7e/0x170
 [<c1093b80>] ? filldir64+0x0/0xf0
 [<c133b153>] ? __mutex_lock_common+0x203/0x310
 [<c1093b80>] ? filldir64+0x0/0xf0
 [<c10df0c7>] reiserfs_readdir+0x17/0x20
 [<c1093eb5>] vfs_readdir+0x85/0xa0
 [<c1093f34>] sys_getdents64+0x64/0xb0
 [<c1002d18>] sysenter_do_call+0x12/0x36
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