lkml.org 
[lkml]   [2018]   [Apr]   [30]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
Date
SubjectRe: [PATCH] softirq: reorder trace_softirqs_on to prevent lockdep splat
On Mon, Apr 30, 2018 at 9:38 AM Steven Rostedt <rostedt@goodmis.org> wrote:

> On Thu, 26 Apr 2018 21:11:00 -0700
> Joel Fernandes <joelaf@google.com> wrote:

> > I'm able to reproduce a lockdep splat when CONFIG_PROVE_LOCKING=y and
> > CONFIG_PREEMPTIRQ_EVENTS=y.
> >
> > $ echo 1 > /d/tracing/events/preemptirq/preempt_enable/enable
> > ---
> > [ 26.112609] DEBUG_LOCKS_WARN_ON(current->softirqs_enabled)
> > [ 26.112636] WARNING: CPU: 0 PID: 118 at kernel/locking/lockdep.c:3854
> > [...]
> > [ 26.144229] Call Trace:
> > [ 26.144926] <IRQ>
> > [ 26.145506] lock_acquire+0x55/0x1b0
> > [ 26.146499] ? __do_softirq+0x46f/0x4d9
> > [ 26.147571] ? __do_softirq+0x46f/0x4d9
> > [ 26.148646] trace_preempt_on+0x8f/0x240
> > [ 26.149744] ? trace_preempt_on+0x4d/0x240
> > [ 26.150862] ? __do_softirq+0x46f/0x4d9
> > [ 26.151930] preempt_count_sub+0x18a/0x1a0
> > [ 26.152985] __do_softirq+0x46f/0x4d9
> > [ 26.153937] irq_exit+0x68/0xe0
> > [ 26.154755] smp_apic_timer_interrupt+0x271/0x280
> > [ 26.156056] apic_timer_interrupt+0xf/0x20
> > [ 26.157105] </IRQ>

> I'm not able to trigger this. Is there more to it?

No that should be it. I have a 100% repro on v4.16. I will try on a newer
kernel and let you know.

thanks,

- Joel

\
 
 \ /
  Last update: 2018-04-30 18:55    [W:0.076 / U:1.208 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site