Re: bcachefs page fault oops after device evacuate/remove and unmount

From: Daniel J Blueman
Date: Thu Nov 30 2023 - 21:59:17 EST


On Thu, 30 Nov 2023 at 20:50, Kent Overstreet <kent.overstreet@xxxxxxxxx> wrote:
>
> On Thu, Nov 30, 2023 at 08:47:33PM -0500, Daniel J Blueman wrote:
> > Hi Kent et al,
> >
> > On upstream bcachefs (master @ evilpiepirate.org/git/bcachefs.git) SHA
> > f8a1ba26, I was able to develop a minimal reproducer [1] for a page
> > not present oops I can provoke [2]. It appears we need further
> > synchronisation during unmount.
> >
> > Let me know when there is a patch I can test, or for debug.
>
> There was a device removal that was just fixed, I've already sent the
> pull request to Linus but in the meantime try this branch:
>
> https://evilpiepirate.org/git/bcachefs.git/log/?h=bcachefs-for-upstream
>
> If you still hit it, I'll turn your reproducer into a ktest test and
> hunt it down.

This did reproduce on the second cycle on bcachefs-for-upstream SHA
415e5107b0dc; let me know if you can't trigger it and I'll make some
adjustments.

Thanks,
Dan
--
Daniel J Blueman