On Wed, Jun 03, 2020 at 04:44:17PM -0700, Guenter Roeck wrote: > > sparc32 smp images in next-20200603 still crash for me with a spinlock > recursion. s390 images hang early in boot. Several others (alpha, arm64, > various ppc) don't even compile. I can run some more bisects over time, > but this is becoming a full-time job :-(. I've been able to bisect s390 hang to commit b614345f52bc ("x86/entry: Clarify irq_{enter,exit}_rcu()"). After this commit, lockdep_hardirq_exit() is called twice on s390 (and others) - one time in irq_exit_rcu() and another one in irq_exit(): /** * irq_exit_rcu() - Exit an interrupt context without updating RCU * * Also processes softirqs if needed and possible. */ void irq_exit_rcu(void) { __irq_exit_rcu(); /* must be last! */ lockdep_hardirq_exit(); } /** * irq_exit - Exit an interrupt context, update RCU and lockdep * * Also processes softirqs if needed and possible. */ void irq_exit(void) { irq_exit_rcu(); rcu_irq_exit(); /* must be last! */ lockdep_hardirq_exit(); } Removing the call in irq_exit() make s390 boot again, and judgung by the x86 entry code, the comment /* must be last! */ is stale... @Peter, @Thomas, can you comment please? >From e51d50ee6f4d1f446decf91c2c67230da14ff82c Mon Sep 17 00:00:00 2001 From: Mike Rapoport <rppt@xxxxxxxxxxxxx> Date: Thu, 4 Jun 2020 12:37:03 +0300 Subject: [PATCH] softirq: don't call lockdep_hardirq_exit() twice After commit b614345f52bc ("x86/entry: Clarify irq_{enter,exit}_rcu()") lockdep_hardirq_exit() is called twice on every architecture that uses irq_exit(): one time in irq_exit_rcu() and another one in irq_exit(). Remove the extra call in irq_exit(). Signed-off-by: Mike Rapoport <rppt@xxxxxxxxxxxxx> --- kernel/softirq.c | 3 --- 1 file changed, 3 deletions(-) diff --git a/kernel/softirq.c b/kernel/softirq.c index a3eb6eba8c41..7523f4ce4c1d 100644 --- a/kernel/softirq.c +++ b/kernel/softirq.c @@ -427,7 +427,6 @@ static inline void __irq_exit_rcu(void) void irq_exit_rcu(void) { __irq_exit_rcu(); - /* must be last! */ lockdep_hardirq_exit(); } @@ -440,8 +439,6 @@ void irq_exit(void) { irq_exit_rcu(); rcu_irq_exit(); - /* must be last! */ - lockdep_hardirq_exit(); } /* -- 2.26.2 > Guenter -- Sincerely yours, Mike. _______________________________________________ linux-snps-arc mailing list linux-snps-arc@xxxxxxxxxxxxxxxxxxx http://lists.infradead.org/mailman/listinfo/linux-snps-arc