Messages in this thread | | | Date | Tue, 23 Apr 2024 15:28:51 -0700 | From | "Paul E. McKenney" <> | Subject | Re: [syzbot] [kernel?] WARNING: suspicious RCU usage in __do_softirq |
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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.
Thanx, Paul
> Thanks > Zqiang > > > ksoftirqd_run_end(); > > cond_resched(); > > return;
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