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Date: Mon, 30 Oct 2000 22:18:48 -0800 (PST)
From: iwaki@bc.niigata-u.ac.jp
To: freebsd-gnats-submit@FreeBSD.org
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Subject: kern/22435: linprocfs causes system down and reboot
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>Number:         22435
>Category:       kern
>Synopsis:       linprocfs causes system down and reboot
>Confidential:   no
>Severity:       critical
>Priority:       high
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Mon Oct 30 22:20:01 PST 2000
>Closed-Date:
>Last-Modified:
>Originator:     Mamoru Iwaki
>Release:        FreeBSD 4.1.1-STABLE
>Organization:
Niigata University
>Environment:
FreeBSD mi000.merlin.gs.niigata-u.ac.jp 4.1.1-STABLE FreeBSD 4.1.1-STABLE #0: Tue Oct 31 14:34:58 JST 2000     root@mi000.merlin.gs.niigata-u.ac.jp:/usr/obj/amd/mi004/home2/FreeBSD-src/stable4/src/sys/MI  i386

>Description:
Using linprocfs on 4.1.1-STABLE system, 

% cat /compat/linux/proc/stat

or

% cat /compat/linux/proc/uptime

cause a panic with the following message

 Fatal trap 18: integer divide fault while in kernel mode
 instruction pointer     = 0x8:0xc0933030
 stack pointer           = 0x10:0xc60dddc8
 frame pointer           = 0x10:0xc60dde20
 code segment            = base 0x0, limit 0xfffff, type 0x1b
                         = DPL 0, pres 1, def32 1, gran 1
 processor eflags        = interrupt enabled, resume, IOPL = 0
 current process         = 325 (cat)
 interrupt mask          = none
 trap number             = 18
 panic: integer divide fault

and then the system reboots immediately.  At least, this problem has
exist since 4.1.1-STABLE around 24 Oct., but around 17 Oct..  

This is dangerous because every user can make system down easily.  

I heard that the CURRENT around 28 Oct. works good with the same
operations, so this problem maybe exist only in 4.1.1-STABLE.  
>How-To-Repeat:
Use the above commands on 4.1.1-STABLE around 24 Oct.  
>Fix:
In private communication, assar@freebsd.org proposed the following 
patch, which looks working well.  

In src/sys/i386/linux/linprocfs, 

--- linprocfs_misc.c.org        Fri Sep 22 17:01:45 2000
+++ linprocfs_misc.c    Tue Oct 31 10:10:18 2000
@@ -65,8 +65,8 @@
 
 #include <i386/linux/linprocfs/linprocfs.h>
 
-#define T2J(x) (((x) * 100) / stathz)
-#define T2S(x) ((x) / stathz)
+#define T2J(x) (((x) * 100) / (stathz ? stathz : hz))		/* ticks to jiffies */
+#define T2S(x) ((x) / (stathz ? stathz : hz))		/* ticks to seconds */
 
 int
 linprocfs_domeminfo(curp, p, pfs, uio)


>Release-Note:
>Audit-Trail:
>Unformatted:


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