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SubjectRe: lockdep with reiserfs

* Yinghai Lu <yinghai@kernel.org> wrote:

> x:~ # mount /dev/sda2 /xx
>
> [ 277.586941] =======================================================
> [ 277.594680] [ INFO: possible circular locking dependency detected ]
> [ 277.601299] 2.6.33-rc1-tip-yh-00304-g97a015d-dirty #1007
> [ 277.605492] -------------------------------------------------------
> [ 277.622611] mount/19427 is trying to acquire lock:
> [ 277.627353] (&journal->j_mutex){+.+...}, at: [<ffffffff811c6d40>]
> do_journal_begin_r+0x9f/0x308

Frederic has posted the patch below to lkml - does it do the trick for you?

Ingo

----- Forwarded message from Frederic Weisbecker <fweisbec@gmail.com> -----

Date: Wed, 16 Dec 2009 23:35:24 +0100
From: Frederic Weisbecker <fweisbec@gmail.com>
To: Alexander Beregalov <a.beregalov@gmail.com>
Cc: LKML <linux-kernel@vger.kernel.org>,
Frederic Weisbecker <fweisbec@gmail.com>,
Alexander Beregalov <a.beregalov@gmail.com>,
Chris Mason <chris.mason@oracle.com>,
Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@elte.hu>
Subject: [PATCH] reiserfs: Fix reiserfs lock <-> inode mutex dependency inversion

The reiserfs lock -> inode mutex dependency gets inverted when we
relax the lock while walking to the tree.

To fix this, use a specialized version of reiserfs_mutex_lock_safe
that takes care of mutex subclasses. Then we can grab the inode
mutex with I_MUTEX_XATTR subclass without any reiserfs lock
dependency.

This fixes the following report:

[ INFO: possible circular locking dependency detected ]
2.6.32-06793-gf405425-dirty #2
-------------------------------------------------------
mv/18566 is trying to acquire lock:
(&REISERFS_SB(s)->lock){+.+.+.}, at: [<c1110708>] reiserfs_write_lock+0x28=
/0x40

but task is already holding lock:
(&sb->s_type->i_mutex_key#5/3){+.+.+.}, at: [<c111033c>]
reiserfs_for_each_xattr+0x10c/0x380

which lock already depends on the new lock.

the existing dependency chain (in reverse order) is:

-> #1 (&sb->s_type->i_mutex_key#5/3){+.+.+.}:
[<c104f723>] validate_chain+0xa23/0xf70
[<c1050155>] __lock_acquire+0x4e5/0xa70
[<c105075a>] lock_acquire+0x7a/0xa0
[<c134c76f>] mutex_lock_nested+0x5f/0x2b0
[<c11102b4>] reiserfs_for_each_xattr+0x84/0x380
[<c1110615>] reiserfs_delete_xattrs+0x15/0x50
[<c10ef57f>] reiserfs_delete_inode+0x8f/0x140
[<c10a565c>] generic_delete_inode+0x9c/0x150
[<c10a574d>] generic_drop_inode+0x3d/0x60
[<c10a4667>] iput+0x47/0x50
[<c109cc0b>] do_unlinkat+0xdb/0x160
[<c109cca0>] sys_unlink+0x10/0x20
[<c1002c50>] sysenter_do_call+0x12/0x36

-> #0 (&REISERFS_SB(s)->lock){+.+.+.}:
[<c104fc68>] validate_chain+0xf68/0xf70
[<c1050155>] __lock_acquire+0x4e5/0xa70
[<c105075a>] lock_acquire+0x7a/0xa0
[<c134c76f>] mutex_lock_nested+0x5f/0x2b0
[<c1110708>] reiserfs_write_lock+0x28/0x40
[<c1103d6b>] search_by_key+0x1f7b/0x21b0
[<c10e73ef>] search_by_entry_key+0x1f/0x3b0
[<c10e77f7>] reiserfs_find_entry+0x77/0x400
[<c10e81e5>] reiserfs_lookup+0x85/0x130
[<c109a144>] __lookup_hash+0xb4/0x110
[<c109b763>] lookup_one_len+0xb3/0x100
[<c1110350>] reiserfs_for_each_xattr+0x120/0x380
[<c1110615>] reiserfs_delete_xattrs+0x15/0x50
[<c10ef57f>] reiserfs_delete_inode+0x8f/0x140
[<c10a565c>] generic_delete_inode+0x9c/0x150
[<c10a574d>] generic_drop_inode+0x3d/0x60
[<c10a4667>] iput+0x47/0x50
[<c10a1c4f>] dentry_iput+0x6f/0xf0
[<c10a1d74>] d_kill+0x24/0x50
[<c10a396b>] dput+0x5b/0x120
[<c109ca89>] sys_renameat+0x1b9/0x230
[<c109cb28>] sys_rename+0x28/0x30
[<c1002c50>] sysenter_do_call+0x12/0x36

other info that might help us debug this:

2 locks held by mv/18566:
#0: (&sb->s_type->i_mutex_key#5/1){+.+.+.}, at: [<c109b6ac>]
lock_rename+0xcc/0xd0
#1: (&sb->s_type->i_mutex_key#5/3){+.+.+.}, at: [<c111033c>]
reiserfs_for_each_xattr+0x10c/0x380

stack backtrace:
Pid: 18566, comm: mv Tainted: G C 2.6.32-06793-gf405425-dirty #2
Call Trace:
[<c134b252>] ? printk+0x18/0x1e
[<c104e790>] print_circular_bug+0xc0/0xd0
[<c104fc68>] validate_chain+0xf68/0xf70
[<c104c8cb>] ? trace_hardirqs_off+0xb/0x10
[<c1050155>] __lock_acquire+0x4e5/0xa70
[<c105075a>] lock_acquire+0x7a/0xa0
[<c1110708>] ? reiserfs_write_lock+0x28/0x40
[<c134c76f>] mutex_lock_nested+0x5f/0x2b0
[<c1110708>] ? reiserfs_write_lock+0x28/0x40
[<c1110708>] ? reiserfs_write_lock+0x28/0x40
[<c134b60a>] ? schedule+0x27a/0x440
[<c1110708>] reiserfs_write_lock+0x28/0x40
[<c1103d6b>] search_by_key+0x1f7b/0x21b0
[<c1050176>] ? __lock_acquire+0x506/0xa70
[<c1051267>] ? lock_release_non_nested+0x1e7/0x340
[<c1110708>] ? reiserfs_write_lock+0x28/0x40
[<c104e354>] ? trace_hardirqs_on_caller+0x124/0x170
[<c104e3ab>] ? trace_hardirqs_on+0xb/0x10
[<c1042a55>] ? T.316+0x15/0x1a0
[<c1042d2d>] ? sched_clock_cpu+0x9d/0x100
[<c10e73ef>] search_by_entry_key+0x1f/0x3b0
[<c134bf2a>] ? __mutex_unlock_slowpath+0x9a/0x120
[<c104e354>] ? trace_hardirqs_on_caller+0x124/0x170
[<c10e77f7>] reiserfs_find_entry+0x77/0x400
[<c10e81e5>] reiserfs_lookup+0x85/0x130
[<c1042d2d>] ? sched_clock_cpu+0x9d/0x100
[<c109a144>] __lookup_hash+0xb4/0x110
[<c109b763>] lookup_one_len+0xb3/0x100
[<c1110350>] reiserfs_for_each_xattr+0x120/0x380
[<c110ffe0>] ? delete_one_xattr+0x0/0x1c0
[<c1003342>] ? math_error+0x22/0x150
[<c1110708>] ? reiserfs_write_lock+0x28/0x40
[<c1110615>] reiserfs_delete_xattrs+0x15/0x50
[<c1110708>] ? reiserfs_write_lock+0x28/0x40
[<c10ef57f>] reiserfs_delete_inode+0x8f/0x140
[<c10a561f>] ? generic_delete_inode+0x5f/0x150
[<c10ef4f0>] ? reiserfs_delete_inode+0x0/0x140
[<c10a565c>] generic_delete_inode+0x9c/0x150
[<c10a574d>] generic_drop_inode+0x3d/0x60
[<c10a4667>] iput+0x47/0x50
[<c10a1c4f>] dentry_iput+0x6f/0xf0
[<c10a1d74>] d_kill+0x24/0x50
[<c10a396b>] dput+0x5b/0x120
[<c109ca89>] sys_renameat+0x1b9/0x230
[<c1042d2d>] ? sched_clock_cpu+0x9d/0x100
[<c104c8cb>] ? trace_hardirqs_off+0xb/0x10
[<c1042dde>] ? cpu_clock+0x4e/0x60
[<c1350825>] ? do_page_fault+0x155/0x370
[<c1041816>] ? up_read+0x16/0x30
[<c1350825>] ? do_page_fault+0x155/0x370
[<c109cb28>] sys_rename+0x28/0x30
[<c1002c50>] sysenter_do_call+0x12/0x36

Reported-by: Alexander Beregalov <a.beregalov@gmail.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Chris Mason <chris.mason@oracle.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
---
fs/reiserfs/xattr.c | 3 ++-
include/linux/reiserfs_fs.h | 9 +++++++++
2 files changed, 11 insertions(+), 1 deletions(-)

diff --git a/fs/reiserfs/xattr.c b/fs/reiserfs/xattr.c
index 58aa8e7..8891cd8 100644
--- a/fs/reiserfs/xattr.c
+++ b/fs/reiserfs/xattr.c
@@ -243,7 +243,8 @@ static int reiserfs_for_each_xattr(struct inode *inode,
goto out_dir;
}

- mutex_lock_nested(&dir->d_inode->i_mutex, I_MUTEX_XATTR);
+ reiserfs_mutex_lock_nested_safe(&dir->d_inode->i_mutex, I_MUTEX_XATTR,
+ inode->i_sb);
buf.xadir = dir;
err = reiserfs_readdir_dentry(dir, &buf, fill_with_dentries, &pos);
while ((err == 0 || err == -ENOSPC) && buf.count) {
diff --git a/include/linux/reiserfs_fs.h b/include/linux/reiserfs_fs.h
index a05b4a2..4351b49 100644
--- a/include/linux/reiserfs_fs.h
+++ b/include/linux/reiserfs_fs.h
@@ -97,6 +97,15 @@ static inline void reiserfs_mutex_lock_safe(struct mutex *m,
reiserfs_write_lock(s);
}

+static inline void
+reiserfs_mutex_lock_nested_safe(struct mutex *m, unsigned int subclass,
+ struct super_block *s)
+{
+ reiserfs_write_unlock(s);
+ mutex_lock_nested(m, subclass);
+ reiserfs_write_lock(s);
+}
+
/*
* When we schedule, we usually want to also release the write lock,
* according to the previous bkl based locking scheme of reiserfs.
--
1.6.2.3
----- End forwarded message -----

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