Re: linux-next: build failure after merge of the block tree

[Jens Axboe]

On 04/26/2016 08:40 AM, Nicolas Pitre wrote:
> On Tue, 26 Apr 2016, Stephen Rothwell wrote:
>
> > Hi Michal,
> >
> > On Tue, 26 Apr 2016 15:30:01 +0200 Michal Marek <mmarek@xxxxxxx> wrote:
> > > On 2016-04-26 05:38, Stephen Rothwell wrote:
> > > > Hi Nicolas,
> > > >
> > > > After merging the block tree, today's linux-next build (powerpc
> > > > ppc64_defconfig) failed like this:
> > > >
> > > > ERROR: ".blk_queue_write_cache" [drivers/block/virtio_blk.ko] undefined!
> > > > ERROR: ".blk_queue_write_cache" [drivers/block/ps3disk.ko] undefined!
> > > > ERROR: ".blk_queue_write_cache" [drivers/block/nbd.ko] undefined!
> > > >
> > > > Caused by commit
> > > >
> > > >    089095b8eef9 ("kbuild: better abstract vmlinux sequential prerequisites")
> > > >
> > > > from the kbuild-pite tree.
> > > >
> > > > I have reverted that commit for today.
> > >
> > > I can't reproduce this with today's linux-next and the revert reverted.
> > > Also, CONFIG_TRIM_UNUSED_KSYMS is disabled in the defconfig as expected,
> > > so I have no idea what went wrong.
> >
> > Yeah, I couldn't figure it out either, but the revert made it work for
> > me.  Could it be that I do incremental builds - so today, I would have
> > built commit b087ce990625 ("Merge remote-tracking branch 'input/next'")
> > which worked, then commit 9d67df654092 ("Merge remote-tracking branch
> > 'block/for-next'") which failed.
> >
> > The only suspect code in the block tree has been there since April 13
> > with no build failures.
> >
> > Anyway, I can see how things go tomorrow, but I hate it when things
> > seem fragile like this.
>
> If you can reproduce this build failure, could you try a make mrproper
> and attempt it again?  I, too, would like to find an explanation and a
> way to reproduce.

I just took a look at it, and it doesn't make any sense to me...

--
Jens Axboe