From: Steven Rostedt <firstname.lastname@example.org> To: Peter Zijlstra <email@example.com> Cc: Tejun Heo <firstname.lastname@example.org>, Ingo Molnar <email@example.com>, firstname.lastname@example.org Subject: Re: [PATCH] scheduler: convert BUG_ON()s in try_to_wake_up_local() to WARN_ON_ONCE()s Date: Tue, 19 Mar 2013 07:29:54 -0400 [thread overview] Message-ID: <email@example.com> (raw) In-Reply-To: <1363688074.22553.14.camel@laptop> On Tue, 2013-03-19 at 11:14 +0100, Peter Zijlstra wrote: > On Mon, 2013-03-18 at 12:22 -0700, Tejun Heo wrote: > > try_to_wake_up_local() should only be invoked to wake up another task > > in the same runqueue and BUG_ON()s are used to enforce the rule. > > Missing try_to_wake_up_local() can stall workqueue execution but such > > stalls are likely to be finite either by another work item being > > queued or the one blocked getting unblocked. There's no reason to > > trigger BUG while holding rq lock crashing the whole system. > > > > Convert BUG_ON()s in try_to_wake_up_local() to WARN_ON_ONCE()s. > > Doesn't really matter either way, the printk()s triggered by either > will very likely kill the system anyhow ;-) Only if something blocks on the console lock, and it tries to wake it up. But even then, it has to be a reverse rq locking order, or wakeup on the same rq that its running on (which is very unlikely). I admit that it doesn't "solve" the bug. But at least there's a chance to investigate what happened when the bug does occur. Right now we have only one conclusion when the bug triggers, and that's a hard lockup. -- Steve
next prev parent reply other threads:[~2013-03-19 11:29 UTC|newest] Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top 2013-03-18 19:22 Tejun Heo 2013-03-18 19:32 ` Steven Rostedt 2013-03-19 10:14 ` Peter Zijlstra 2013-03-19 11:29 ` Steven Rostedt [this message] 2013-03-21 18:14 ` [tip:sched/urgent] sched: Convert BUG_ON() s " tip-bot for Tejun Heo
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