Messages in this thread | | | Date | Mon, 24 Oct 2022 13:20:57 +0100 | From | Mark Rutland <> | Subject | Re: [BUG] possible deadlock in __rcu_irq_enter_check_tick |
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On Thu, Oct 20, 2022 at 09:32:35PM +0800, Yu Liao wrote: > On 2022/10/19 22:14, Mark Rutland wrote: > > On Tue, Oct 18, 2022 at 03:24:48PM +0100, Mark Rutland wrote:
> > Having a go with v6.1-rc1, placing a kprobe on __rcu_irq_enter_check_tick() > > causes a recursive exception which triggers the stack overflow detection, so > > there are bigger problems here, and we'll need to do some further rework of the > > arm64 entry code. FWIW, x86-64 seems fine. > > > > I have a vague recollection that that there was something (some part kprobes, > > perhaps) that didn't like being called in NMI context, which is why debug > > exceptions aren't accounted as true NMIs (but get most of the same treatment). > > > > I'll have to dig into this a bit more; there are a bunch of subtle interactions > > in this area, and I don't want to put a band-aid over this without fully > > understanding the implications. > > > > Once we've figured that out for mainline, we can figure out what needs to go to > > stable. > > > > Yu, were you particularly interested in tracing __rcu_irq_enter_check_tick(), > > or did you stumble upon this by other means?
> Oh,This was found with the help of the kernel fuzzer syzkaller.
Thanks for confirming!
I've also been testing with Syzkaller, but it looks like I haven't had KPROBES enabled due to deselecting MODULE support, which explains how I've missed this until now. :/
I'll go fiddle with moy configs.
Thanks, Mark.
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