linux-kernel - Re: Regression in 2.6.25-rc3: s2ram segfaults before suspending

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Date:	Thu, 28 Feb 2008 08:08:55 +0100
From:	"Klaus S. Madsen" <ksm@...rnemadsen.org>
To:	LKML <linux-kernel@...r.kernel.org>
Cc:	Ingo Molnar <mingo@...e.hu>, Pavel Machek <pavel@....cz>,
	"Rafael J. Wysocki" <rjw@...k.pl>
Subject: Re: Regression in 2.6.25-rc3: s2ram segfaults before suspending

On Wed, Feb 27, 2008 at 23:10:33 +0100, Klaus S. Madsen wrote:
> Hi all,
> 
> 	I have a Thinkpad T61p, which I'm able to suspend with s2ram on
> Linux 2.6.24.3. However when I try to suspend it on 2.6.25-rc3, s2ram
> dies after changing to vt1, with a segfault. I'm using s2ram from cvs,
> and libx86 version 0.99 from http://www.codon.org.uk/~mjg59/libx86/.
> 
> Some details about the segfault:
> 
> $ sudo gdb ./s2ram
> (gdb) run
> Starting program: /home/ksm/downloads/suspend/s2ram 
> Switching from vt7 to vt1
> Calling get_mode
> 
> Program received signal SIGSEGV, Segmentation fault.
> 0xb7facf4a in run_vm86 () at lrmi.c:526
> 526             asm volatile (
> (gdb) list
> 521     static int
> 522     lrmi_vm86(struct vm86_struct *vm)
> 523     {
> 524             int r;
> 525     #ifdef __PIC__
> 526             asm volatile (
> 527              "pushl %%ebx\n\t"
> 528              "movl %2, %%ebx\n\t"
> 529              "int $0x80\n\t"
> 530              "popl %%ebx"
> (gdb) bt 
> #0  0xb7facf4a in run_vm86 () at lrmi.c:526
> #1  0xb7fad61b in LRMI_int (i=16, r=0xbffca670) at lrmi.c:844
> #2  0x0804acfc in do_vbe_service (AX=20227, BX=0, regs=0xbffca670)
>     at vbetool/vbetool.c:158
> #3  0x0804af7e in __get_mode () at vbetool/vbetool.c:453
> #4  0x0804a30f in s2ram_hacks () at s2ram-x86.c:268
> #5  0x0804954f in main (argc=1, argv=0x0) at s2ram-main.c:92
> 
> I have tried to bisect the problem, and it fingered the following
> commit:
> 
> commit 82bc03fc158e28c90d7ed9919410776039cb4e14
> Author: Ingo Molnar <mingo@...e.hu>
> 
>     x86: add PWT to NOCACHE flags
> 
> Reverting this commit in the bisected tree (by executing git show
> 82bc03fc158e28c90d7ed9919410776039cb4e14 | patch -R -p1), makes the
> segfault go away. I've run make clean between each kernel compile, to be
> sure the tree was correctly compiled.
> 
> I have attached the .config I'm using for 2.6.25-rc3 (when bisecting, I
> just choose the default on every question). If necessary, I can try to
> reconstruct the one I ended up with after the bisection.
I have attached my .config now, in case it's important.

-- 
Kind regards
	Klaus S. Madsen

View attachment "config-t61p.txt" of type "text/plain" (50563 bytes)