From: Frederic Weisbecker <fweisbec@gmail.com>
To: LKML <linux-kernel@vger.kernel.org>
Cc: LKML <linux-kernel@vger.kernel.org>,
Frederic Weisbecker <fweisbec@gmail.com>,
Alexander Beregalov <a.beregalov@gmail.com>,
Chris Mason <chris.mason@oracle.com>, Ingo Molnar <mingo@elte.hu>,
Christian Kujau <lists@nerdbynature.de>
Subject: [PATCH 1/5] reiserfs: Relax lock before open xattr dir in reiserfs_xattr_set_handle()
Date: Wed, 30 Dec 2009 21:42:23 +0100 [thread overview]
Message-ID: <1262205747-9208-2-git-send-regression-fweisbec@gmail.com> (raw)
In-Reply-To: <1262150491-9983-1-git-send-regression-fweisbec@gmail.com>
We call xattr_lookup() from reiserfs_xattr_get(). We then hold
the reiserfs lock when we grab the i_mutex. But later, we may
relax the reiserfs lock, creating dependency inversion between
both locks.
The lookups and creation jobs ar already protected by the
inode mutex, so we can safely relax the reiserfs lock, dropping
the unwanted reiserfs lock -> i_mutex dependency, as shown
in the following lockdep report:
=======================================================
[ INFO: possible circular locking dependency detected ]
2.6.32-atom #173
-------------------------------------------------------
cp/3204 is trying to acquire lock:
(&REISERFS_SB(s)->lock){+.+.+.}, at: [<c11432b9>] reiserfs_write_lock_once+0x29/0x50
but task is already holding lock:
(&sb->s_type->i_mutex_key#4/3){+.+.+.}, at: [<c1141e18>] open_xa_dir+0xd8/0x1b0
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #1 (&sb->s_type->i_mutex_key#4/3){+.+.+.}:
[<c105ea7f>] __lock_acquire+0x11ff/0x19e0
[<c105f2c8>] lock_acquire+0x68/0x90
[<c1401a2b>] mutex_lock_nested+0x5b/0x340
[<c1141d83>] open_xa_dir+0x43/0x1b0
[<c1142722>] reiserfs_for_each_xattr+0x62/0x260
[<c114299a>] reiserfs_delete_xattrs+0x1a/0x60
[<c111ea1f>] reiserfs_delete_inode+0x9f/0x150
[<c10c9c32>] generic_delete_inode+0xa2/0x170
[<c10c9d4f>] generic_drop_inode+0x4f/0x70
[<c10c8b07>] iput+0x47/0x50
[<c10c0965>] do_unlinkat+0xd5/0x160
[<c10c0a00>] sys_unlink+0x10/0x20
[<c1002ec4>] sysenter_do_call+0x12/0x32
-> #0 (&REISERFS_SB(s)->lock){+.+.+.}:
[<c105f176>] __lock_acquire+0x18f6/0x19e0
[<c105f2c8>] lock_acquire+0x68/0x90
[<c1401a2b>] mutex_lock_nested+0x5b/0x340
[<c11432b9>] reiserfs_write_lock_once+0x29/0x50
[<c1117012>] reiserfs_lookup+0x62/0x140
[<c10bd85f>] __lookup_hash+0xef/0x110
[<c10bf21d>] lookup_one_len+0x8d/0xc0
[<c1141e2a>] open_xa_dir+0xea/0x1b0
[<c1141fe5>] xattr_lookup+0x15/0x160
[<c1142476>] reiserfs_xattr_get+0x56/0x2a0
[<c1144042>] reiserfs_get_acl+0xa2/0x360
[<c114461a>] reiserfs_cache_default_acl+0x3a/0x160
[<c111789c>] reiserfs_mkdir+0x6c/0x2c0
[<c10bea96>] vfs_mkdir+0xd6/0x180
[<c10c0c10>] sys_mkdirat+0xc0/0xd0
[<c10c0c40>] sys_mkdir+0x20/0x30
[<c1002ec4>] sysenter_do_call+0x12/0x32
other info that might help us debug this:
2 locks held by cp/3204:
#0: (&sb->s_type->i_mutex_key#4/1){+.+.+.}, at: [<c10bd8d6>] lookup_create+0x26/0xa0
#1: (&sb->s_type->i_mutex_key#4/3){+.+.+.}, at: [<c1141e18>] open_xa_dir+0xd8/0x1b0
stack backtrace:
Pid: 3204, comm: cp Not tainted 2.6.32-atom #173
Call Trace:
[<c13ff993>] ? printk+0x18/0x1a
[<c105d33a>] print_circular_bug+0xca/0xd0
[<c105f176>] __lock_acquire+0x18f6/0x19e0
[<c105d3aa>] ? check_usage+0x6a/0x460
[<c105f2c8>] lock_acquire+0x68/0x90
[<c11432b9>] ? reiserfs_write_lock_once+0x29/0x50
[<c11432b9>] ? reiserfs_write_lock_once+0x29/0x50
[<c1401a2b>] mutex_lock_nested+0x5b/0x340
[<c11432b9>] ? reiserfs_write_lock_once+0x29/0x50
[<c11432b9>] reiserfs_write_lock_once+0x29/0x50
[<c1117012>] reiserfs_lookup+0x62/0x140
[<c105ccca>] ? debug_check_no_locks_freed+0x8a/0x140
[<c105cbe4>] ? trace_hardirqs_on_caller+0x124/0x170
[<c10bd85f>] __lookup_hash+0xef/0x110
[<c10bf21d>] lookup_one_len+0x8d/0xc0
[<c1141e2a>] open_xa_dir+0xea/0x1b0
[<c1141fe5>] xattr_lookup+0x15/0x160
[<c1142476>] reiserfs_xattr_get+0x56/0x2a0
[<c1144042>] reiserfs_get_acl+0xa2/0x360
[<c10ca2e7>] ? new_inode+0x27/0xa0
[<c114461a>] reiserfs_cache_default_acl+0x3a/0x160
[<c1402eb7>] ? _spin_unlock+0x27/0x40
[<c111789c>] reiserfs_mkdir+0x6c/0x2c0
[<c10c7cb8>] ? __d_lookup+0x108/0x190
[<c105c932>] ? mark_held_locks+0x62/0x80
[<c1401c8d>] ? mutex_lock_nested+0x2bd/0x340
[<c10bd17a>] ? generic_permission+0x1a/0xa0
[<c11788fe>] ? security_inode_permission+0x1e/0x20
[<c10bea96>] vfs_mkdir+0xd6/0x180
[<c10c0c10>] sys_mkdirat+0xc0/0xd0
[<c10505c6>] ? up_read+0x16/0x30
[<c1002fd8>] ? restore_all_notrace+0x0/0x18
[<c10c0c40>] sys_mkdir+0x20/0x30
[<c1002ec4>] sysenter_do_call+0x12/0x32
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Alexander Beregalov <a.beregalov@gmail.com>
Cc: Chris Mason <chris.mason@oracle.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Christian Kujau <lists@nerdbynature.de>
---
fs/reiserfs/xattr.c | 9 +++++++--
1 files changed, 7 insertions(+), 2 deletions(-)
diff --git a/fs/reiserfs/xattr.c b/fs/reiserfs/xattr.c
index c320c77..78a3f24 100644
--- a/fs/reiserfs/xattr.c
+++ b/fs/reiserfs/xattr.c
@@ -485,11 +485,16 @@ reiserfs_xattr_set_handle(struct reiserfs_transaction_handle *th,
if (!buffer)
return lookup_and_delete_xattr(inode, name);
+ reiserfs_write_unlock(inode->i_sb);
dentry = xattr_lookup(inode, name, flags);
- if (IS_ERR(dentry))
+ if (IS_ERR(dentry)) {
+ reiserfs_write_lock(inode->i_sb);
return PTR_ERR(dentry);
+ }
- reiserfs_down_read_safe(&REISERFS_I(inode)->i_xattr_sem, inode->i_sb);
+ down_read(&REISERFS_I(inode)->i_xattr_sem);
+
+ reiserfs_write_lock(inode->i_sb);
xahash = xattr_hash(buffer, buffer_size);
while (buffer_pos < buffer_size || buffer_pos == 0) {
--
1.6.2.3
next prev parent reply other threads:[~2009-12-30 20:43 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-12-30 5:21 [PATCH 0/4] Some reiserfs fixes Frederic Weisbecker
2009-12-30 5:21 ` [PATCH 1/4] reiserfs: Fix reiserfs lock <-> i_xattr_sem dependency inversion Frederic Weisbecker
2009-12-30 5:21 ` [PATCH 2/4] reiserfs: Warn on lock relax if taken recursively Frederic Weisbecker
2009-12-30 5:21 ` [PATCH 3/4] reiserfs: Fix reiserfs lock <-> i_mutex dependency inversion on xattr Frederic Weisbecker
2009-12-30 20:27 ` [PATCH 3/4 v2] " Frederic Weisbecker
2009-12-30 5:21 ` [PATCH 4/4] reiserfs: Relax reiserfs lock while freeing the journal Frederic Weisbecker
2009-12-30 6:53 ` [PATCH 0/4] Some reiserfs fixes Frederic Weisbecker
2009-12-30 20:42 ` [PATCH 0/5] reiserfs lock inversion fixes on xattr Frederic Weisbecker
2009-12-31 6:32 ` Christian Kujau
2010-01-01 9:29 ` Ingo Molnar
2010-01-02 3:52 ` Frederic Weisbecker
2010-01-02 1:40 ` Frederic Weisbecker
2009-12-30 20:42 ` Frederic Weisbecker [this message]
2009-12-30 20:42 ` [PATCH 2/5] reiserfs: Fix unwanted recursive reiserfs lock in reiserfs_unlink() Frederic Weisbecker
2009-12-30 20:42 ` [PATCH 3/5] reiserfs: Fix journal mutex <-> inode mutex lock inversion Frederic Weisbecker
2009-12-30 20:42 ` [PATCH 4/5] reiserfs: Safely acquire i_mutex from reiserfs_for_each_xattr Frederic Weisbecker
2009-12-30 20:42 ` [PATCH 5/5] reiserfs: Safely acquire i_mutex from xattr_rmdir Frederic Weisbecker
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