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

[Stephen Rothwell]

Hi Greg,

On Mon, 9 Jan 2012 07:42:59 -0800 Greg KH <greg@xxxxxxxxx> wrote:
>
> On Mon, Jan 09, 2012 at 05:20:16PM +1100, Stephen Rothwell wrote:
> > On Mon, 9 Jan 2012 16:59:50 +1100 Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx> wrote:
> > >
> > > On Thu, 5 Jan 2012 16:04:48 -0800 Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> wrote:
> > > >
> > > > On Thu, 5 Jan 2012 19:04:05 +1100
> > > > Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx> wrote:
> > > > 
> > > > > After merging the final tree, today's linux-next build (sparc64 defconfig)
> > > > > failed like this:
> > > > > 
> > > > > In file included from include/trace/ftrace.h:567:0,
> > > > >                  from include/trace/define_trace.h:86,
> > > > >                  from include/trace/events/power.h:240,
> > > > >                  from kernel/trace/power-traces.c:14:
> > > > > include/trace/events/kmem.h: In function 'ftrace_test_probe_kmalloc':
> > > > > include/trace/events/kmem.h:45:1: error: implicit declaration of function 'check_trace_callback_type_kmalloc' [-Werror=implicit-function-declaration]
> > > > > include/trace/events/kmem.h: In function 'ftrace_test_probe_kmem_cache_alloc':
> > > > >
> > > > > ...
> > > > >
> > > > > include/trace/events/kmem.h:267:1: error: implicit declaration of function 'check_trace_callback_type_mm_page_alloc_extfrag' [-Werror=implicit-function-declaration]
> > > > > In file included from include/trace/ftrace.h:774:0,
> > > > >                  from include/trace/define_trace.h:86,
> > > > >                  from include/trace/events/power.h:240,
> > > > >                  from kernel/trace/power-traces.c:14:
> > > > > include/trace/events/kmem.h: In function 'perf_test_probe_mm_page_pcpu_drain':
> > > > > include/trace/events/kmem.h:256:1: error: implicit declaration of function 'check_trace_callback_type_mm_page_pcpu_drain' [-Werror=implicit-function-declaration]
> > > > > 
> > > > > I have no idea what has gone wrong here, but I did not get this error
> > > > > yesterday.  The only thing that touched include/trace/events/kmem.h is
> > > > > patch "mm-tracepoint: rename page-free events" from the akpm tree, but
> > > > > that was there yesterday as well and doesn't look suspicious.
> > > > 
> > > > Yes, it's not due to anything in the akpm tree.  Tracing stuff blew up.
> > > > 
> > > > > I just have to leave things broken for today in the hope that someone
> > > > > figures something out.  This does not affect my X86_64 allmodconfig build
> > > > > or my PowerPC builds (including an allyesconfig build).
> > > > 
> > > > It fails with sparc64 defconfig but succeeds with sparc64 allmodconfig.
> > > > Some config-dependent thing.  3.2 is OK, so it's something in -next.
> > > > 
> > > > It could be that some far-off sparc64 Kconfig change is newly
> > > > triggering this.  
> > > > 
> > > > I suppose I could get off my ass and actually work out why it broke,
> > > > but the tracing code is too icky.
> > > 
> > > This failure is now in Linus' tree.  I am not sure when it got there.
> > 
> > Bisected down to:
> > 
> > 8a25a2fd126c621f44f3aeaef80d51f00fc11639 is the first bad commit
> > commit 8a25a2fd126c621f44f3aeaef80d51f00fc11639
> > Author: Kay Sievers <kay.sievers@xxxxxxxx>
> > Date:   Wed Dec 21 14:29:42 2011 -0800
> > 
> >     cpu: convert 'cpu' and 'machinecheck' sysdev_class to a regular subsystem
> 
> How is this triggering this build problem?  I didn't see this happen
> before, and it wasn't showing up in linux-next in the past, right?

I think this error showed up the first time that the sysdev removal stuff
was included in linux-next i.e. after the other errors/warnings had been
dealt with.

> This patch has nothing to to with tracing, perhaps it is an #include
> file problem?  Or is the build error a different one (remember the
> -Werror problem in linux-next that I fixed up for PPC?)
> 
> confused,

The tracing code is obscure and I suspect that there may be some ordering
issue in there.  What seems to have triggered this is the include of
device.h instead of sysdev.h in cpu.h.  This has caused a whole lot more
tracepoints(?) to be defined.

So it is a side effect and needs the tracing guys to track it down :-(
-- 
Cheers,
Stephen Rothwell                    sfr@xxxxxxxxxxxxxxxx
http://www.canb.auug.org.au/~sfr/

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