[tip:core/urgent] lockdep: Fix check_usage_backwards() error message
From: tip-bot for Oleg Nesterov
Date: Wed Jan 27 2010 - 08:16:21 EST
Commit-ID: 48d50674179981e41f432167b2441cec782d5484
Gitweb: http://git.kernel.org/tip/48d50674179981e41f432167b2441cec782d5484
Author: Oleg Nesterov <oleg@xxxxxxxxxx>
AuthorDate: Tue, 26 Jan 2010 19:16:41 +0100
Committer: Ingo Molnar <mingo@xxxxxxx>
CommitDate: Wed, 27 Jan 2010 08:34:02 +0100
lockdep: Fix check_usage_backwards() error message
Lockdep has found the real bug, but the output doesn't look right to me:
> =========================================================
> [ INFO: possible irq lock inversion dependency detected ]
> 2.6.33-rc5 #77
> ---------------------------------------------------------
> emacs/1609 just changed the state of lock:
> (&(&tty->ctrl_lock)->rlock){+.....}, at: [<ffffffff8127c648>] tty_fasync+0xe8/0x190
> but this lock took another, HARDIRQ-unsafe lock in the past:
> (&(&sighand->siglock)->rlock){-.....}
"HARDIRQ-unsafe" and "this lock took another" looks wrong, afaics.
> ... key at: [<ffffffff81c054a4>] __key.46539+0x0/0x8
> ... acquired at:
> [<ffffffff81089af6>] __lock_acquire+0x1056/0x15a0
> [<ffffffff8108a0df>] lock_acquire+0x9f/0x120
> [<ffffffff81423012>] _raw_spin_lock_irqsave+0x52/0x90
> [<ffffffff8127c1be>] __proc_set_tty+0x3e/0x150
> [<ffffffff8127e01d>] tty_open+0x51d/0x5e0
The stack-trace shows that this lock (ctrl_lock) was taken under
->siglock (which is hopefully irq-safe).
This is a clear typo in check_usage_backwards() where we tell the print a
fancy routine we're forwards.
Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
LKML-Reference: <20100126181641.GA10460@xxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
---
kernel/lockdep.c | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)
diff --git a/kernel/lockdep.c b/kernel/lockdep.c
index 5feaddc..c62ec14 100644
--- a/kernel/lockdep.c
+++ b/kernel/lockdep.c
@@ -2147,7 +2147,7 @@ check_usage_backwards(struct task_struct *curr, struct held_lock *this,
return ret;
return print_irq_inversion_bug(curr, &root, target_entry,
- this, 1, irqclass);
+ this, 0, irqclass);
}
void print_irqtrace_events(struct task_struct *curr)
--
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