On Mon, 10 Aug 2020 at 22:18, Thomas Gleixner <[email protected]> wrote: > Marco Elver <[email protected]> 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/[email protected] > > Fixes: 248591f5d257 ("kcsan: Make KCSAN compatible with new IRQ state > > tracking") > > Reported-by: [email protected] > > Co-developed-by: Peter Zijlstra (Intel) <[email protected]> > > Signed-off-by: Marco Elver <[email protected]> > > --- > > 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 <[email protected]>
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/[email protected]/) Thanks, -- Marco
