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.
