PROBLEM: Kernel hangs and/or becomes unstable

Prashant TR (prashant_tr@yahoo.com)
Tue, 31 Aug 1999 00:34:29 -0700 (PDT)


There are two bugs:

1> Kernel Crashes
2> Kernel becomes very unstable

I'm not sure what can be done about the 1st bug since I don't know how
to reproduce it but the other one is highly reproducible.

My system configuration:

CPU: Intel Pentium (P54C) with F00F bug. (stepping 0Ch)
Kernel version: 2.2.5-15
Kernel Modules: 2.2.121
GNU C: egcs-2.91.66
Binutils: 2.9.1.0.23
Linux C Library: 2.1.1
Dynamic linker: ldd (GNU libc) 2.1.1
Procps: 2.0.2
Mount: 2.9o
Net Tools: (1999-01-31)
Kbd: [option...]
Sh-utils: 1.16
Modules loaded: nls_iso8859-1 nls_cp437 vfat vfat opl3 sb uart401 sound
soundlow soundcore

BUG 1: (UNKNOWN REASON)

The kernel hanged when I was playing DOOM. It uses SVGALIB and I feel
it has something to do with the I/O permissions or the sound driver.
But I couldn't reproduce this bug.

The CPU "froze" and nothing worked. I could not even switch to another
console or reboot the system. Ctrl-Alt-Del failed. Only the sound was
being played perfectly. It was apparent that the CPU had halted
completely since there was no sound from both my hard drives and
nothing else was responding.

All this happened when I was in the superuser mode. There was no other
console where I had logged on.

BUG 2: ("FORK"ING CONTINUOUSLY MAKES THE SYSTEM UNSTABLE)

The system runs out of resources then I run this simple program. This
need not be run at the superuser level. The code is shown below.

int main()
{
while (1) fork();
return 0;
}

Run this as a background process: ./a.out &

If this program is run even for a few seconds the system runs out of
resources. None of the commands except "pwd" and the very primitive
ones work (not even ls). I switched over to another console where I had
logged on as root. I issued "init 0" and it took 15 minutes to respond
to this command. I saw only one "OK" messsage that is normally
displayed while shutting down and this took 45 minutes. I didn't have
the patience to see ot shut down completely and I reset the system. I
also tried "killall" but the same thing essentially happens.

It seems that the "fork.c" in the kernel sources has a bug. I looked at
the listing but couldn't figure out anything. Doesn't Linux allocate
some specific amount of resources for a user rather than allocating
everything ?

Thank you,
Prashant TR

IF THIS/THESE BUG(S) CAN BE FIXED, PLEASE LET ME KNOW WHERE I CAN GET
THE PATCH FOR THIS. I HAVE IMPORTANT DATA ON MY SYSTEM AND CANNOT
AFFORD TO RISK ANYTHING.

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