Re: page fault in pfioctl
- Reply: Andriy Gapon : "Re: page fault in pfioctl"
- In reply to: Kristof Provost : "Re: page fault in pfioctl"
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Date: Sat, 25 Sep 2021 16:38:11 UTC
On 25/09/2021 19:34, Kristof Provost wrote: > On 25 Sep 2021, at 18:25, Andriy Gapon wrote: >> On 13/06/2021 11:19, Kristof Provost wrote: >>> On 13 Jun 2021, at 09:41, Andriy Gapon <avg@freebsd.org> wrote: >>>> Based on >>>> the panic message (page fault with non-sleepable locks held), it seems that >>>> the problem is with holding the lock across the copyout. Usually that >>>> won't panic, but if the destination happens to be paged out... And only >>>> with INVARIANTS, I guess... >>> >>> Oh right. Thanks. I’ve gotten bitten by that one before, but had clearly >>> garbage collected the memory. >>> >>> I’ll fix this one and check for others on Monday. >>> >>> I’ll also see of we can persuade copyout to always panic on this bug, not >>> just when the destination memory is actually paged out. That way we’ll catch >>> this in the regression tests in the future. >> >> I upgraded to the latest stable/13 and hit a fresh panic of the same type. >> This time it's in pf_getstatus() and it's a copyout while 'pf rulesets' lock is held. >> > I believe that’s fixed by https://cgit.freebsd.org/src/commit/sys/netpfil/pf/pf_ioctl.c?id=cb13059663e455b3fc69c293dadec53c164490dc Thank you for the pointer! I believe it should help with the witness warning. Still not sure what's going on with copyout_nosmap_std(). -- Andriy Gapon