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

[triaxx%NetBSD.org@localhost]

The following reply was made to PR kern/58043; it has been noted by GNATS.

From: triaxx%NetBSD.org@localhost
To: Paul Goyette <paul%whooppee.com@localhost>, gnats-bugs%netbsd.org@localhost
Cc: kern-bug-people%netbsd.org@localhost, gnats-admin%netbsd.org@localhost, netbsd-bugs%netbsd.org@localhost
Subject: Re: kern/58043: kernel crash in assert_sleepable() in -current, dk(4)
 driver?
Date: Wed, 27 Mar 2024 11:55:11 +0100

 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)
 >> Â Â Â Â Â Â Â Â  return;
 >> Â Â Â Â  }
 >>
 >> -Â Â Â  /* Defer to thread if system is low on memory. */
 >> +Â Â Â  /* Always defer to thread. */
 >> Â Â Â Â  bufq_put(cs->sc_bufq, bp);
 >> -Â Â Â  if (__predict_false(ccdbackoff(cs))) {
 >> -Â Â Â Â Â Â Â  mutex_exit(cs->sc_iolock);
 >> -#ifdef DEBUG
 >> -Â Â Â Â Â Â Â Â  if (ccddebug & CCDB_FOLLOW)
 >> -Â Â Â Â Â Â Â Â Â Â Â Â  printf("ccdstrategy: holding off on I/O\n");
 >> -#endif
 >> -Â Â Â Â Â Â Â  return;
 >> -Â Â Â  }
 >> -Â Â Â  ccdstart(cs);
 >> +Â Â Â  cv_broadcast(&cs->sc_push);
 >> +Â Â Â  mutex_exit(cs->sc_iolock);
 >> Â }
 >>
 >> Â static void