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Date: Wed, 24 Oct 2007 20:06:57 +0200
From: Jens Axboe <jens.axboe@oracle.com>
To: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>
Cc: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>, apw@shadowen.org,
       linux-kernel@vger.kernel.org
Subject: Re: [BUG] 2.6.23-git18 Kernel oops in sg helpers
Message-ID: <20071024180656.GF14671@kernel.dk>
References: <471E110C.20404@linux.vnet.ibm.com> <20071023184419.GD14671@kernel.dk> <20071024115436.GT32058@shadowen.org> <20071024214014C.fujita.tomonori@lab.ntt.co.jp> <471F6DFE.3040304@linux.vnet.ibm.com>
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On Wed, Oct 24 2007, Kamalesh Babulal wrote:
> FUJITA Tomonori wrote:
> > On Wed, 24 Oct 2007 12:54:36 +0100
> > Andy Whitcroft <apw@shadowen.org> wrote:
> > 
> >> On Tue, Oct 23, 2007 at 08:44:20PM +0200, Jens Axboe wrote:
> >>> On Tue, Oct 23 2007, Kamalesh Babulal wrote:
> >>>> Hi,
> >>>>
> >>>> Kernel oops is triggered while running fsx-linux test, followed by cpu softlock
> >>>> over the AMD box
> >>>>
> >>>> Unable to handle kernel NULL pointer dereference at 0000000000000018 RIP: 
> >>>>  [<ffffffff8021f2f6>] gart_map_sg+0x26c/0x406
> >>>> PGD 10185b067 PUD 10075b067 PMD 0 
> >>>> Oops: 0002 [1] SMP 
> >>>> CPU 3 
> >>>> Modules linked in:
> >>>> Pid: 18676, comm: fsx-linux Not tainted 2.6.23-git18-autokern1 #1
> >>>> RIP: 0010:[<ffffffff8021f2f6>]  [<ffffffff8021f2f6>] gart_map_sg+0x26c/0x406
> >>>> RSP: 0000:ffff810181edf948  EFLAGS: 00010002
> >>> Can you check where gart_map_sg+0x26c is at? Make sure you have
> >>> CONFIG_DEBUG_INFO defined, then do:
> >>>
> >>> $ gdb vmlinux
> >>> $ l *gart_map_sg+0x26c
> >> Ok, this problem still seems to be about in 2.6.24-rc1.  Here is the gdb
> >> output from that version, the panic (also below) seems the same:
> >>
> >> (gdb) l *gart_map_sg+0x26c
> >> 0xffffffff8022011e is in gart_map_sg (arch/x86/kernel/pci-gart_64.c:433).
> >> 428                     goto error;
> >> 429             out++;
> >> 430             flush_gart();
> >> 431             if (out < nents) {
> >> 432                     sgmap = sg_next(sgmap);
> >> 433                     sgmap->dma_length = 0;
> >> 434             }
> >> 435             return out;
> >> 436
> >> 437     error:
> >>
> >> So it seems sg_next has returned 0.
> > 
> > Have you tried this?
> > 
> > http://marc.info/?l=linux-kernel&m=119317981406073&w=2
> > -
> Hi,
> Thanks, this patch solves the kernel oops.

Tomo, please do write the proper changelog so we can get this upstream.

-- 
Jens Axboe

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