Messages in this thread |  | | Subject | Re: 5.13-rt1 + KVM = WARNING: at fs/eventfd.c:74 eventfd_signal() | From | Daniel Bristot de Oliveira <> | Date | Thu, 15 Jul 2021 14:34:25 +0200 |
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On 7/15/21 11:46 AM, Paolo Bonzini wrote: > On 15/07/21 10:22, Daniel Bristot de Oliveira wrote: >> On 7/14/21 12:35 PM, Paolo Bonzini wrote: >>> On 14/07/21 11:23, Jason Wang wrote: >>>> I think this can be probably fixed here: >>>> >>>> https://lore.kernel.org/lkml/20210618084412.18257-1-zhe.he@windriver.com/ >>> >>> That seems wrong; in particular it wouldn't protect against AB/BA deadlocks. >>> In fact, the bug is with the locking; the code assumes that >>> spin_lock_irqsave/spin_unlock_irqrestore is non-preemptable and therefore >>> increments and decrements the percpu variable inside the critical section. >>> >>> This obviously does not fly with PREEMPT_RT; the right fix should be >>> using a local_lock. Something like this (untested!!): >> >> the lock needs to be per-pcu... > > Great, thanks for testing and fixing the patch! Are you going to post > it again once you've confirmed it works?
I can do that... unless you want to send it yourself...
-- Daniel
> Paolo
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