NetBSD Problem Report #59727

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Message-Id: <20251026093950.ABF971A923A@mollari.NetBSD.org>
Date: Sun, 26 Oct 2025 09:39:50 +0000 (UTC)
From: nia@pkgsrc.org
Reply-To: nia@pkgsrc.org
To: gnats-bugs@NetBSD.org
Subject: wsmux changes in April 2025 seem to have broken kqueue on wsmux
X-Send-Pr-Version: www-1.0

>Number:         59727
>Category:       kern
>Synopsis:       wsmux changes in April 2025 seem to have broken kqueue on wsmux
>Confidential:   no
>Severity:       critical
>Priority:       medium
>Responsible:    hans
>State:          closed
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Sun Oct 26 09:40:00 +0000 2025
>Closed-Date:    Thu Nov 27 15:53:29 +0000 2025
>Last-Modified:  Thu Nov 27 15:53:29 +0000 2025
>Originator:     nia
>Release:        -11, -current...
>Organization:
The NetBSD Foundation
>Environment:
NetBSD siphon 11.99.3 NetBSD 11.99.3 (SIPHON) #13: Thu Oct 23 23:06:13 CEST 2025  nia@siphon:/encrypt/obj/sys/arch/amd64/compile/SIPHON amd64
>Description:
System panicked: kernel diagnostic assertion "sc->sc_base.me_evp == NULL" failed: file "/encrypt/src/sys/dev/wscons/wsmux.c", line 592 wsmuxkqfilter: not open

Backtrace from time of crash is available.
crash> bt
vmx_insn_failinvalid() at 0
kern_reboot() at kern_reboot+0x5f
vpanic() at vpanic+0x193
kern_assert() at __x86_indirect_thunk_rax
wsmuxkqfilter() at wsmuxkqfilter+0x78
cdev_kqfilter() at cdev_kqfilter+0x7f
spec_kqfilter() at spec_kqfilter+0x71
VOP_KQFILTER() at VOP_KQFILTER+0x5c
kevent1() at kevent1+0xfe5
sys___kevent100() at sys___kevent100+0x35
syscall() at syscall+0x9d
--- syscall (number 501) ---
syscall+0x9d:
>How-To-Repeat:
install wm/velox, follow the instructions in MESSAGE to run it, observe
instant panic
>Fix:
revert wsmux changes from 2025 that replaced diagnostic checks with
asserts

>Release-Note:

>Audit-Trail:

Responsible-Changed-From-To: kern-bug-people->hans
Responsible-Changed-By: nia@NetBSD.org
Responsible-Changed-When: Sun, 26 Oct 2025 12:58:50 +0000
Responsible-Changed-Why:
can you take a look? thanks :)


State-Changed-From-To: open->analyzed
State-Changed-By: nia@NetBSD.org
State-Changed-When: Sun, 26 Oct 2025 12:58:50 +0000
State-Changed-Why:





From: Martin Husemann <martin@duskware.de>
To: gnats-bugs@NetBSD.org
Cc: hans@NetBSD.org
Subject: Re: kern/59727: wsmux changes broke kqueue
Date: Fri, 21 Nov 2025 20:43:45 +0100

 Any update on this?

 Nia, could you undo that hunk (like below) and run a ktrace of your
 reproducer?

 Martin

 Index: wsmux.c
 ===================================================================
 RCS file: /cvsroot/src/sys/dev/wscons/wsmux.c,v
 retrieving revision 1.68
 diff -u -p -r1.68 wsmux.c
 --- wsmux.c	7 Apr 2025 11:18:44 -0000	1.68
 +++ wsmux.c	21 Nov 2025 19:42:58 -0000
 @@ -589,7 +589,12 @@ wsmuxkqfilter(dev_t dev, struct knote *k
  		return (1);
  	}

 -	KASSERTMSG(sc->sc_base.me_evp == NULL, "wsmuxkqfilter: not open\n");
 +	if (sc->sc_base.me_evp == NULL) {
 +#ifdef DIAGNOSTIC
 +		printf("wsmuxkqfilter: not open\n");
 +#endif
 +		return (1);
 +	}

  	return (wsevent_kqfilter(sc->sc_base.me_evp, kn));
  }

From: "Taylor R Campbell" <riastradh@netbsd.org>
To: gnats-bugs@gnats.NetBSD.org
Cc: 
Subject: PR/59727 CVS commit: src/sys/dev/wscons
Date: Sat, 22 Nov 2025 15:39:24 +0000

 Module Name:	src
 Committed By:	riastradh
 Date:		Sat Nov 22 15:39:24 UTC 2025

 Modified Files:
 	src/sys/dev/wscons: wsmux.c

 Log Message:
 wsmux(4): Fix sense of assertion in kqfilter.

 This was recently changed in rev. 1.68 to tighten bogus run-time
 conditionals into assertions -- with a small snag in this particular
 hunk:

 @@ -613,12 +589,7 @@ wsmuxkqfilter(dev_t dev, struct knote *kn)
  		return (1);
  	}

 -	if (sc->sc_base.me_evp == NULL) {
 -#ifdef DIAGNOSTIC
 -		printf("wsmuxkqfilter: not open\n");
 -#endif
 -		return (1);
 -	}
 +	KASSERTMSG(sc->sc_base.me_evp == NULL, "wsmuxkqfilter: not open\n");

  	return (wsevent_kqfilter(sc->sc_base.me_evp, kn));
  }

 An astute reader will notice that there is something amiss in the
 translation from `if (<cond>)' to `KASSERTMSG(<cond>, ...)'.

 Candidate fix for:

 PR kern/59727: wsmux changes in April 2025 seem to have broken kqueue
 on wsmux

 (Evidently we need some better testing for all this wscons(4)
 business.)


 To generate a diff of this commit:
 cvs rdiff -u -r1.68 -r1.69 src/sys/dev/wscons/wsmux.c

 Please note that diffs are not public domain; they are subject to the
 copyright notices on the relevant files.

State-Changed-From-To: analyzed->needs-pullups
State-Changed-By: nia@NetBSD.org
State-Changed-When: Sat, 22 Nov 2025 17:17:15 +0000
State-Changed-Why:



From: "Martin Husemann" <martin@netbsd.org>
To: gnats-bugs@gnats.NetBSD.org
Cc: 
Subject: PR/59727 CVS commit: [netbsd-11] src/sys/dev/wscons
Date: Mon, 24 Nov 2025 16:50:18 +0000

 Module Name:	src
 Committed By:	martin
 Date:		Mon Nov 24 16:50:18 UTC 2025

 Modified Files:
 	src/sys/dev/wscons [netbsd-11]: wsmux.c

 Log Message:
 Pull up following revision(s) (requested by nia in ticket #101):

 	sys/dev/wscons/wsmux.c: revision 1.69

 wsmux(4): Fix sense of assertion in kqfilter.

 This was recently changed in rev. 1.68 to tighten bogus run-time
 conditionals into assertions -- with a small snag in this particular
 hunk:
 @@ -613,12 +589,7 @@ wsmuxkqfilter(dev_t dev, struct knote *kn)
                 return (1);
         }
 -       if (sc->sc_base.me_evp == NULL) {
 -#ifdef DIAGNOSTIC
 -               printf("wsmuxkqfilter: not open\n");
 -#endif
 -               return (1);
 -       }
 +       KASSERTMSG(sc->sc_base.me_evp == NULL, "wsmuxkqfilter: not open\n");
         return (wsevent_kqfilter(sc->sc_base.me_evp, kn));
  }

 An astute reader will notice that there is something amiss in the
 translation from `if (<cond>)' to `KASSERTMSG(<cond>, ...)'.
 Candidate fix for:

 PR kern/59727: wsmux changes in April 2025 seem to have broken kqueue
 on wsmux

 (Evidently we need some better testing for all this wscons(4)
 business.)


 To generate a diff of this commit:
 cvs rdiff -u -r1.68 -r1.68.2.1 src/sys/dev/wscons/wsmux.c

 Please note that diffs are not public domain; they are subject to the
 copyright notices on the relevant files.

State-Changed-From-To: needs-pullups->closed
State-Changed-By: nia@NetBSD.org
State-Changed-When: Thu, 27 Nov 2025 15:53:29 +0000
State-Changed-Why:


>Unformatted:

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