Re: kernel BUG at block/bio.c:1787! while initializing scsi_debug on ppc64 host

[Eryu Guan <guaneryu@gmail.com>]

On Tue, Dec 15, 2015 at 09:27:14PM +0800, Ming Lei wrote:
> On Tue, Dec 15, 2015 at 9:06 PM, Eryu Guan <guaneryu@gmail.com> wrote:
> > On Tue, Dec 15, 2015 at 08:06:47PM +0800, Ming Lei wrote:
> >> On Tue, Dec 15, 2015 at 7:20 PM, Eryu Guan <guaneryu@gmail.com> wrote:
> >> > On Fri, Dec 11, 2015 at 07:53:40PM +0800, Eryu Guan wrote:
> >> >> Hi,
> >> >>
> >> >> I saw this kernel BUG_ON on 4.4-rc4 kernel, and this can be reproduced
> >> >> easily on ppc64 host by:
> >> >
> >> > This is still reproducible with 4.4-rc5 kernel.
> >>
> >> Could you capture the debug log after appyling the attached patch and
> >> the reproduction?
> >
> > Thanks for looking into this! dmesg shows:
> >
> > [  686.217682] bio_split: sectors 0, bio_sectors 128, bi_rw 0
> 
> Then I guess queue_max_sectors(q) is bad, could you apply the
> attached patch(and the last patch) and post the log?

[  301.279018] blk_bio_segment_split: nseg 0, max_secs 64, max segs 2048
[  301.279023]   bv.len 65536, bv.offset 0
[  301.279026] bio_split: sectors 0, bio_sectors 128, bi_rw 0

If full call trace is needed please let me know.

Thanks,
Eryu