From 48d50674179981e41f432167b2441cec782d5484 Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Tue, 26 Jan 2010 19:16:41 +0100 Subject: [PATCH] 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: [] 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: [] __key.46539+0x0/0x8 > ... acquired at: > [] __lock_acquire+0x1056/0x15a0 > [] lock_acquire+0x9f/0x120 > [] _raw_spin_lock_irqsave+0x52/0x90 > [] __proc_set_tty+0x3e/0x150 > [] 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 Signed-off-by: Peter Zijlstra LKML-Reference: <20100126181641.GA10460@redhat.com> Signed-off-by: Ingo Molnar --- kernel/lockdep.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/lockdep.c b/kernel/lockdep.c index 5feaddcdbe49..c62ec14609b9 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)