From: Z qiang <qiang.zhang1211@gmail.com>
To: paulmck@kernel.org
Cc: Thomas Gleixner <tglx@linutronix.de>,
syzbot <syzbot+dce04ed6d1438ad69656@syzkaller.appspotmail.com>,
linux-kernel@vger.kernel.org, peterz@infradead.org,
syzkaller-bugs@googlegroups.com
Subject: Re: [syzbot] [kernel?] WARNING: suspicious RCU usage in __do_softirq
Date: Fri, 26 Apr 2024 10:09:39 +0800 [thread overview]
Message-ID: <CALm+0cVvM56xse8ejf7+Wro+XBkFwY-MO1jyhWcVU8BWaZ2qjg@mail.gmail.com> (raw)
In-Reply-To: <b735d174-8ad9-4ace-86ee-75dc09852537@paulmck-laptop>
>
> On Tue, Apr 23, 2024 at 10:20:49AM +0800, Z qiang wrote:
> > >
> > > On Fri, Apr 19 2024 at 13:50, Z qiang wrote:
> > > >> On Thu, Apr 18, 2024 at 05:49:38PM +0800, Z qiang wrote:
> > > > static __init int spawn_ksoftirqd(void)
> > > > {
> > > > + int cpu;
> > > > +
> > > > + for_each_possible_cpu(cpu)
> > > > + per_cpu(ksoftirqd_work, cpu) = false;
> > >
> > > First of all that initialization is pointless, but why making all of
> > > this complex as hell?
> > >
> > > Thanks,
> > >
> > > tglx
> > > ---
> > > diff --git a/kernel/softirq.c b/kernel/softirq.c
> > > index b315b21fb28c..e991d735be0d 100644
> > > --- a/kernel/softirq.c
> > > +++ b/kernel/softirq.c
> > > @@ -508,7 +508,7 @@ static inline bool lockdep_softirq_start(void) { return false; }
> > > static inline void lockdep_softirq_end(bool in_hardirq) { }
> > > #endif
> > >
> > > -asmlinkage __visible void __softirq_entry __do_softirq(void)
> > > +static void handle_softirqs(bool kirqd)
> > > {
> > > unsigned long end = jiffies + MAX_SOFTIRQ_TIME;
> > > unsigned long old_flags = current->flags;
> > > @@ -563,8 +563,7 @@ asmlinkage __visible void __softirq_entry __do_softirq(void)
> > > pending >>= softirq_bit;
> > > }
> > >
> > > - if (!IS_ENABLED(CONFIG_PREEMPT_RT) &&
> > > - __this_cpu_read(ksoftirqd) == current)
> > > + if (!IS_ENABLED(CONFIG_PREEMPT_RT) && kirqd)
> > > rcu_softirq_qs();
> > >
> > > local_irq_disable();
> > > @@ -584,6 +583,11 @@ asmlinkage __visible void __softirq_entry __do_softirq(void)
> > > current_restore_flags(old_flags, PF_MEMALLOC);
> > > }
> > >
> > > +asmlinkage __visible void __softirq_entry __do_softirq(void)
> > > +{
> > > + handle_softirqs(false);
> > > +}
> > > +
> > > /**
> > > * irq_enter_rcu - Enter an interrupt context with RCU watching
> > > */
> > > @@ -921,7 +925,7 @@ static void run_ksoftirqd(unsigned int cpu)
> > > * We can safely run softirq on inline stack, as we are not deep
> > > * in the task stack here.
> > > */
> > > - __do_softirq();
> > > + handle_softirqs(true);
> >
> > Thanks, this is good for me :),
> > Paul, what do you think?
>
> This looks quite nice to me, especially given that it avoids changing
> all the other calls to __do_softirq(). Some architectures might want
> to directly call handle_softirqs(), but if so, they can send the patches.
Hello, Thomas
Can you send an official patch? or I will send and add you to
Co-developed-by tags.
Thanks
Zqiang
>
> Thanx, Paul
>
> > Thanks
> > Zqiang
> >
> > > ksoftirqd_run_end();
> > > cond_resched();
> > > return;
next prev parent reply other threads:[~2024-04-26 2:09 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-02 18:05 [syzbot] [kernel?] WARNING: suspicious RCU usage in __do_softirq syzbot
2024-04-16 7:05 ` syzbot
2024-04-16 8:10 ` Z qiang
2024-04-16 8:44 ` Z qiang
2024-04-17 1:13 ` Paul E. McKenney
2024-04-17 2:25 ` Z qiang
2024-04-17 22:39 ` Paul E. McKenney
2024-04-18 9:49 ` Z qiang
2024-04-18 22:49 ` Paul E. McKenney
2024-04-19 5:50 ` Z qiang
2024-04-19 6:11 ` Z qiang
2024-04-19 7:12 ` Paul E. McKenney
2024-04-19 7:29 ` Z qiang
2024-04-22 21:15 ` Thomas Gleixner
2024-04-23 2:20 ` Z qiang
2024-04-23 22:28 ` Paul E. McKenney
2024-04-26 2:09 ` Z qiang [this message]
2024-04-26 17:23 ` Thomas Gleixner
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