Messages in this thread | | | From | Marco Elver <> | Date | Mon, 17 Aug 2020 09:10:32 +0200 | Subject | Re: [PATCH] kcsan: Treat runtime as NMI-like with interrupt tracing |
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On Tue, 11 Aug 2020 at 08:56, Marco Elver <elver@google.com> wrote: > On Mon, 10 Aug 2020 at 22:18, Thomas Gleixner <tglx@linutronix.de> wrote: > > Marco Elver <elver@google.com> writes: > > > Since KCSAN instrumentation is everywhere, we need to treat the hooks > > > NMI-like for interrupt tracing. In order to present an as 'normal' as > > > possible context to the code called by KCSAN when reporting errors, we > > > need to update the IRQ-tracing state. > > > > > > Tested: Several runs through kcsan-test with different configuration > > > (PROVE_LOCKING on/off), as well as hours of syzbot testing with the > > > original config that caught the problem (without CONFIG_PARAVIRT=y, > > > which appears to cause IRQ state tracking inconsistencies even when > > > KCSAN remains off, see Link). > > > > > > Link: https://lkml.kernel.org/r/0000000000007d3b2d05ac1c303e@google.com > > > Fixes: 248591f5d257 ("kcsan: Make KCSAN compatible with new IRQ state tracking") > > > Reported-by: syzbot+8db9e1ecde74e590a657@syzkaller.appspotmail.com > > > Co-developed-by: Peter Zijlstra (Intel) <peterz@infradead.org> > > > Signed-off-by: Marco Elver <elver@google.com> > > > --- > > > Patch Note: This patch applies to latest mainline. While current > > > mainline suffers from the above problem, the configs required to hit the > > > issue are likely not enabled too often (of course with PROVE_LOCKING on; > > > we hit it on syzbot though). It'll probably be wise to queue this as > > > normal on -rcu, just in case something is still off, given the > > > non-trivial nature of the issue. (If it should instead go to mainline > > > right now as a fix, I'd like some more test time on syzbot.) > > > > I'd rather stick it into mainline before -rc1. > > > > Reviewed-by: Thomas Gleixner <tglx@linutronix.de> > > Thank you, sounds good. > > FWIW I let it run on syzkaller over night once more, rebased against > Sunday's mainline, and found no DEBUG_LOCKDEP issues. (It still found > the known issue in irqentry_exit(), but is not specific to KCSAN: > https://lore.kernel.org/lkml/000000000000e3068105ac405407@google.com/)
I lost track of what's happening with the IRQ state tracking patches. Do we still need this?
Or would Peter's new approach (to make raw->non-raw work) supersede this patch? https://lkml.kernel.org/r/20200811201755.GI35926@hirez.programming.kicks-ass.net
Which would appear to be the nicer solution.
Thanks, -- Marco
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