Messages in this thread | | | Date | Fri, 17 Jun 2022 18:51:48 +0200 | From | Sebastian Andrzej Siewior <> | Subject | Re: [PATCH printk v5 1/1] printk: extend console_lock for per-console locking |
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On 2022-06-09 14:27:11 [+0200], Jason A. Donenfeld wrote: > Hi Dmitry, > > On Thu, Jun 09, 2022 at 02:18:19PM +0200, Dmitry Vyukov wrote: > > > AFAIK, CONFIG_PROVE_RAW_LOCK_NESTING is useful for teasing out cases > > > where RT's raw spinlocks will nest wrong with RT's sleeping spinlocks. > > > But nobody who wants an RT kernel will be using KFENCE. So this seems > > > like a non-issue? Maybe just add a `depends on !KFENCE` to > > > PROVE_RAW_LOCK_NESTING? > > > > Don't know if there are other good solutions (of similar simplicity). > > Fortunately, I found one that solves things without needing to > compromise on anything: > https://lore.kernel.org/lkml/20220609121709.12939-1-Jason@zx2c4.com/ > > > Btw, should this new CONFIG_PROVE_RAW_LOCK_NESTING be generally > > enabled on testing systems? We don't have it enabled on syzbot. > > Last time I spoke with RT people about this, the goal was eventually to > *always* enable it when lock proving is enabled, but there are too many > bugs and cases now to do that, so it's an opt-in. I might be > misremembering, though, so CC'ing Sebastian in case he wants to chime > in.
That is basically still the case. If CONFIG_PROVE_RAW_LOCK_NESTING yells then there will be yelling on PREEMPT_RT, too. We would like to get things fixed ;)
Without going through this thread, John is looking at printk and printk triggers a few of those. That is one of reasons why this is not enabled by default.
> Jason
Sebastian
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