Messages in this thread | | | Date | Tue, 1 Dec 2020 15:51:16 +0100 | From | Peter Zijlstra <> | Subject | Re: [PATCH 1/2] sched/idle: Fix arch_cpu_idle() vs tracing |
| |
On Tue, Dec 01, 2020 at 12:56:27PM +0100, Sven Schnelle wrote: > Hi Peter, > > Peter Zijlstra <peterz@infradead.org> writes: > > > On Mon, Nov 30, 2020 at 01:00:03PM -0800, Guenter Roeck wrote: > >> On Fri, Nov 20, 2020 at 12:41:46PM +0100, Peter Zijlstra wrote: > >> > We call arch_cpu_idle() with RCU disabled, but then use > >> > local_irq_{en,dis}able(), which invokes tracing, which relies on RCU. > >> > > >> > Switch all arch_cpu_idle() implementations to use > >> > raw_local_irq_{en,dis}able() and carefully manage the > >> > lockdep,rcu,tracing state like we do in entry. > >> > > >> > (XXX: we really should change arch_cpu_idle() to not return with > >> > interrupts enabled) > >> > > >> > >> Has this patch been tested on s390 ? Reason for asking is that it causes > >> all my s390 emulations to crash. Reverting it fixes the problem. > > > > My understanding is that it changes the error on s390. Previously it > > would complain about the local_irq_enable() in arch_cpu_idle(), now it > > complains when taking an interrupt during idle. > > I looked into adding the required functionality for s390, but the code > we would need to add to entry.S is rather large - as you noted we would > have to duplicate large portions of irqentry_enter() into our code. > Given that s390 was fine before that patch, can you revert it and submit > it again during the next merge window?
So the thing that got me started here was:
https://lkml.kernel.org/r/yt9dimbm79qi.fsf@linux.ibm.com/
And I got a very similar report from Mark for arm64. I'm not sure what you meanwhile did to get rid of that. But I'm struggling to understand how s390 can work on v5.10-rc5.
There's just too much calling into tracing while RCU is stopped.
| |