Re: kern/58043: kernel crash in assert_sleepable() in -current, dk(4) driver?

[triaxx%NetBSD.org@localhost]

I have a system with:

    $ dmesg -t | grep ccd
    dk7 at wd1: "ccd0p0", 488397088 blocks at 40, type: ccd
    dk8 at wd2: "ccd0p1", 488397088 blocks at 40, type: ccd
    ccd0: Interleaving 2 components (63 block interleave)
    ccd0: /dev/dk7 (488397042 blocks)
    ccd0: /dev/dk8 (488397042 blocks)
    ccd0: total 976794084 blocks
    ccd0: GPT GUID: 546b7b1d-bf71-46a2-9788-226ebaf7ae2d
    dk12 at ccd0: "ccd0", 976794008 blocks at 40, type: ffs

The patch fixes the issue with the kernel that crashes on this system.

> I've already converted my config to raid0 instead of ccd, so I am sorry
> that I am unable to test the patch.  :-(
>
> On Mon, 18 Mar 2024, J. Hannken-Illjes wrote:
>
> > The following reply was made to PR kern/58043; it has been noted by 
> > GNATS.
> >
> > From: "J. Hannken-Illjes" <hannken%mailbox.org@localhost>
> > To: gnats-bugs%netbsd.org@localhost
> > Cc:
> > Subject: Re: kern/58043: kernel crash in assert_sleepable() in 
> > -current, dk(4)
> > driver?
> > Date: Mon, 18 Mar 2024 10:52:09 +0100
> >
> > Paul,
> >
> > please try the attached patch -- if it prevents assert_sleepable() to 
> > fire
> > it is the call to CCD_GETBUF() aka. pool_cache_get(ccd_cache, PR_WAITOK)
> > from softint context that has to be fixed.
> >
> > --
> > J. Hannken-Illjes - hannken%mailbox.org@localhost <mailto:hannken%mailbox.org@localhost>
> >
> > ccd_defer
> >
> > Always defer requests to the helper thread so ccdstart() doesn't
> > get called from softint anymore.
> >
> > diff -r 8b8d2498ffd9 -r 2ec4e85f1120 sys/dev/ccd.c
> > --- sys/dev/ccd.c
> > +++ sys/dev/ccd.c
> > @@ -777,17 +777,10 @@ ccdstrategy(struct buf *bp)
> >          return;
> >      }
> >
> > -    /* Defer to thread if system is low on memory. */
> > +    /* Always defer to thread. */
> >      bufq_put(cs->sc_bufq, bp);
> > -    if (__predict_false(ccdbackoff(cs))) {
> > -        mutex_exit(cs->sc_iolock);
> > -#ifdef DEBUG
> > -         if (ccddebug & CCDB_FOLLOW)
> > -             printf("ccdstrategy: holding off on I/O\n");
> > -#endif
> > -        return;
> > -    }
> > -    ccdstart(cs);
> > +    cv_broadcast(&cs->sc_push);
> > +    mutex_exit(cs->sc_iolock);
> >  }
> >
> >  static void