[parisc-linux] Kernel 2.4 bug (fwd)

[parisc-linux] Kernel 2.4 bug (fwd)

[Roy Keene]

Btw, `submit@bugs.parisc-linux.org' doesn't work.

---------- Forwarded message ----------
Date: Tue, 20 Apr 2004 00:34:27 -0500 (CDT)
From: Roy Keene <parisc@rkeene.org>
To: submit@bugs.parisc-linux.org
Subject: Kernel 2.4 bug

I'd like to report a bug in the main kernel and parisc patched kernel, it
can be reliably reproduced:

do_page_fault() pid=10963 command='test' type=15 address=0x00042004
vm_start = 0x00021000, vm_end = 0x00042000

     YZrvWESTHLNXBCVMcbcbcbcbOGFRQPDI
PSW: 00000000000001100000000000001111 Not tainted
r00-03  00000000 40183344 400a90e3 40187c50
r04-07  40186108 40187c50 00020ade 00000001
r08-11  00020ae6 000de988 00000000 00000000
r12-15  000e29c8 000a0800 000ddca8 000e1dc8
r16-19  000e29c8 00000000 00000000 40186108
r20-23  fffdf048 00000048 00020fb9 00020fb8
r24-27  00021050 00042000 00021048 000209d0
r28-31  00000000 00000000 bff00a40 400a8a93
sr0-3   0000003f 0000003f 00000000 0000003f
sr4-7   0000003f 0000003f 0000003f 0000003f

IASQ: 0000003f 0000003f IAOQ: 400aac07 400aac0b
 IIR: 0f28109d    ISR: 0000003f  IOR: 00042004
 CPU:        0   CR30: 37fb0000 CR31: 10380000
 ORIG_R28: 00021000



I'm running:
Linux hammer.oc9.org 2.4.25-pa0 #3 Fri Mar 12 19:49:36 CST 2004 parisc GNU/Linux

This is my CPU information:
processor       : 0
cpu family      : PA-RISC 2.0
cpu             : PA8500 (PCX-W)
cpu MHz         : 400.000000
model           : 9000/785/C3000
model name      : AllegroHigh W
hversion        : 0x00005bb0
sversion        : 0x00000481
I-cache         : 512 KB
D-cache         : 1024 KB (WB)
ITLB entries    : 160
DTLB entries    : 160 - shared with ITLB
bogomips        : 799.53
software id     : 2007272275

This is the source to cause the problem:
#include <unistd.h>
#include <stdlib.h>

int main(void) {
        char *x;
        x=malloc(4096);
        x[0]='0';
        x[4095]='0';
        free(x);
        free(x);
        return(0);
}



(double free() shouldn't cause the kernel to give page faults, running it
 enough times eventually crashes the kernel)

Re: [parisc-linux] Kernel 2.4 bug (fwd)

[Randolph Chung]

> (double free() shouldn't cause the kernel to give page faults, running it
>  enough times eventually crashes the kernel)

actually, the page fault message from the kernel is just informational.
it tells you what is the processor state when you get a segfault. it's
quite useful for some types of debugging.

however, this should NOT cause your kernel to crash. When your kernel
crashes, do you see a different type of register dump show up? does the
machine hang? hpmc? print some errors? the important bit to look at is
the IAOQ listed in the register dump. If the last 2 bits are set, then
it's a userspace page fault (and should be safe). If you get one where
the last 2 bits are 0 then it's a kernel-space fault, and we should try
to figure out where that comes from.

randolph
-- 
Randolph Chung
Debian GNU/Linux Developer, hppa/ia64 ports
http://www.tausq.org/

Re: [parisc-linux] Kernel 2.4 bug (fwd)

[Roy Keene]

When it crashes I get no messages :-)

There might be something on the serial console, but I've never been
attached to it when it happened.

On Mon, 19 Apr 2004, Randolph Chung wrote:

> > (double free() shouldn't cause the kernel to give page faults, running it
> >  enough times eventually crashes the kernel)
>
> actually, the page fault message from the kernel is just informational.
> it tells you what is the processor state when you get a segfault. it's
> quite useful for some types of debugging.
>
> however, this should NOT cause your kernel to crash. When your kernel
> crashes, do you see a different type of register dump show up? does the
> machine hang? hpmc? print some errors? the important bit to look at is
> the IAOQ listed in the register dump. If the last 2 bits are set, then
> it's a userspace page fault (and should be safe). If you get one where
> the last 2 bits are 0 then it's a kernel-space fault, and we should try
> to figure out where that comes from.
>
> randolph
> --
> Randolph Chung
> Debian GNU/Linux Developer, hppa/ia64 ports
> http://www.tausq.org/
>

Re: [parisc-linux] Kernel 2.4 bug (fwd)

[Randolph Chung]

In reference to a message from Roy Keene, dated Apr 20:
> When it crashes I get no messages :-)
> 
> There might be something on the serial console, but I've never been
> attached to it when it happened.

try some of the steps at:
http://www.parisc-linux.org/faq/kernelbug-howto.html

randolph
-- 
Randolph Chung
Debian GNU/Linux Developer, hppa/ia64 ports
http://www.tausq.org/

Re: [parisc-linux] Kernel 2.4 bug (fwd)

[Matthew Wilcox]

On Tue, Apr 20, 2004 at 12:41:23AM -0500, Roy Keene wrote:
> Btw, `submit@bugs.parisc-linux.org' doesn't work.

Where do you see that email address still?  It should have been removed ...

> (double free() shouldn't cause the kernel to give page faults, running it
>  enough times eventually crashes the kernel)

What you see there is debug information to help you diagnose your app's
breakage ;-).  You can turn it off by changing #define PRINT_USER_FAULTS
to #undef PRINT_USER_FAULTS in arch/parisc/mm/fault.c.  I believe the
Debian kernel does this by default.

Eventually crashinig the kernel is a different matter.  Can you provide
more information about this?

-- 
"Next the statesmen will invent cheap lies, putting the blame upon 
the nation that is attacked, and every man will be glad of those
conscience-soothing falsities, and will diligently study them, and refuse
to examine any refutations of them; and thus he will by and by convince 
himself that the war is just, and will thank God for the better sleep 
he enjoys after this process of grotesque self-deception." -- Mark Twain

Re: [parisc-linux] Kernel 2.4 bug (fwd)

[Roy Keene]

http://parisc-linux.org/   -> "Bug Reporting" (http://bugs.parisc-linux.org/Reporting.html)

How to report a bug in PA-RISC Linux

Send mail to submit@bugs.parisc-linux.org, as described below.

Please don't report several unrelated bugs - especially ones in different
packages - in one message. Also, please don't mail your bug report to any
mailing lists or recipients other than submit@bugs.parisc-linux.org (for
details of how to do this right, see below).



If these are informational only messages they may not be what's causing
the crashes, but they're all I see before the crash occurs (immediately
before)

On Tue, 20 Apr 2004, Matthew Wilcox wrote:

> On Tue, Apr 20, 2004 at 12:41:23AM -0500, Roy Keene wrote:
> > Btw, `submit@bugs.parisc-linux.org' doesn't work.
>
> Where do you see that email address still?  It should have been removed ...
>
> > (double free() shouldn't cause the kernel to give page faults, running it
> >  enough times eventually crashes the kernel)
>
> What you see there is debug information to help you diagnose your app's
> breakage ;-).  You can turn it off by changing #define PRINT_USER_FAULTS
> to #undef PRINT_USER_FAULTS in arch/parisc/mm/fault.c.  I believe the
> Debian kernel does this by default.
>
> Eventually crashinig the kernel is a different matter.  Can you provide
> more information about this?
>
> --
> "Next the statesmen will invent cheap lies, putting the blame upon
> the nation that is attacked, and every man will be glad of those
> conscience-soothing falsities, and will diligently study them, and refuse
> to examine any refutations of them; and thus he will by and by convince
> himself that the war is just, and will thank God for the better sleep
> he enjoys after this process of grotesque self-deception." -- Mark Twain
>

Re: [parisc-linux] Kernel 2.4 bug (fwd)

[Grant Grundler]

On Tue, Apr 20, 2004 at 07:48:12AM -0500, Roy Keene wrote:
> http://parisc-linux.org/   -> "Bug Reporting" (http://bugs.parisc-linux.org/Reporting.html)

Roy,
thanks!

I've hacked that page to redirect folks to the right mailing lists now.
I've attempted to remove or cleaned up (nearly) all references
to bugs.parisc-linux.org.

[ If other on p-l team don't agree with my wording, I don't blame
  ya since it's almost midnight here and I'm too tired to write
  something shorter. ]

I have one more change for the parisc-linux.org navigation bar
but will for now just leave it...I'm thinking "Report.html"
file really belongs in our CVS tree and will move/change that later.

thanks,
grant