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Date: Fri, 27 Apr 2001 10:18:23 -0400 (EDT)
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Cc:
Subject: Kernel panic during ktrace (vrele: negative ref cnt)
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>Number:         26896
>Category:       kern
>Synopsis:       Kernel panic during ktrace (vrele: negative ref cnt)
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    freebsd-bugs
>State:          closed
>Quarter:        
>Keywords:       
>Date-Required:  
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Fri Apr 27 07:20:01 PDT 2001
>Closed-Date:    Thu Jan 10 11:11:54 PST 2002
>Last-Modified:  Thu Jan 10 11:12:16 PST 2002
>Originator:     Jim Hranicky (jfh@cise.ufl.edu)
>Release:        FreeBSD 4.3-STABLE i386
>Organization:
University of Florida CISE Department
>Environment:

	System: FreeBSD 4.3-STABLE #2: Mon Apr 23 14:49:54 EDT 2001 
		700MHz Pentium III
		Intel 440BX motherboard
		ad0: 19470MB <WDC WD204BA>

>Description:
	
	Panic immediately after running "ktrace -C" to end a
	"ktrace -id -p <pid>" process. From the dump:

	   (kgdb) where
	   #0  dumpsys () at /usr/src/sys/kern/kern_shutdown.c:469
	   #1  0xc019d0d7 in boot (howto=256)
	       at /usr/src/sys/kern/kern_shutdown.c:309
	   #2  0xc019d46d in panic (fmt=0xc03448dc "vrele: negative ref cnt")
	       at /usr/src/sys/kern/kern_shutdown.c:556
	   #3  0xc01c9356 in vrele (vp=0xd2a37c80)
	       at /usr/src/sys/kern/vfs_subr.c:1452
	   #4  0xc01975dd in ktrops (curp=0xd1f1aa00, p=0xd29912a0, ops=1, facs=254,
	       vp=0x0) at /usr/src/sys/kern/kern_ktrace.c:411
	   #5  0xc019761a in ktrsetchildren (curp=0xd1f1aa00, top=0xd1f1de00, ops=1,
	       facs=254, vp=0x0) at /usr/src/sys/kern/kern_ktrace.c:431
	   #6  0xc019742e in ktrace (curp=0xd1f1aa00, uap=0xd2962f80)
	       at /usr/src/sys/kern/kern_ktrace.c:330
	   #7  0xc03042a9 in syscall2 (frame={tf_fs = 47, tf_es = 47, tf_ds = 47,
	         tf_edi = -1077938544, tf_esi = 1, tf_ebp = -1077938636,
	         tf_isp = -761909292, tf_ebx = 1, tf_edx = -2012235704, tf_ecx = 11,
	         tf_eax = 45, tf_trapno = 12, tf_err = 2, tf_eip = -2012608448,
	         tf_cs = 31, tf_eflags = 582, tf_esp = -1077938808, tf_ss = 47})
	       at /usr/src/sys/i386/i386/trap.c:1150
	   #8  0xc02f5a45 in Xint0x80_syscall ()
	   #9  0x80487e5 in ?? ()

	This is the second panic in vrele due to negative ref cnts in as many days
	at my site.

	kernel and dump are available if anyone needs them.

>How-To-Repeat:
	Unknown
>Fix:
	Unknown
>Release-Note:
>Audit-Trail:
State-Changed-From-To: open->closed 
State-Changed-By: dd 
State-Changed-When: Sat Apr 28 19:03:52 PDT 2001 
State-Changed-Why:  
Duplicate of 26878 

http://www.freebsd.org/cgi/query-pr.cgi?pr=26896 
State-Changed-From-To: closed->open 
State-Changed-By: dd 
State-Changed-When: Sat Apr 28 20:13:18 PDT 2001 
State-Changed-Why:  
Last close was bogus; even though the error message is the same, it 
seems to be a different problem. 

http://www.freebsd.org/cgi/query-pr.cgi?pr=26896 
State-Changed-From-To: open->closed 
State-Changed-By: silby 
State-Changed-When: Thu Jan 10 11:11:54 PST 2002 
State-Changed-Why:  
kern_ktrace 1.57 sounds like it fixes this problem: 

Fix ktrace enablement/disablement races that can result in a vnode 
ref count panic. 

Bug noticed by: ps 
Reviewed by:    ps 
MFC after:      1 day 

If somehow this can still be reproduced, the PR can be reopened. 

http://www.FreeBSD.org/cgi/query-pr.cgi?pr=26896 
>Unformatted:
