Re: [BUG] next-20081216 - WARNING: at kernel/smp.c:333 smp_call_function_mask

Kamalesh Babulal
2008-12-26T17:05:30Z

* Ingo Molnar <mingo@elte.hu> [2008-12-26 16:33:18]:

>
> * Kamalesh Babulal <kamalesh@linux.vnet.ibm.com> wrote:
>
> > * Sam Ravnborg <sam@ravnborg.org> [2008-12-26 11:27:16]:
> >
> > > On Fri, Dec 26, 2008 at 02:05:47AM -0800, Yinghai Lu wrote:
> > > > Kamalesh Babulal wrote:
> > > > > * Yinghai Lu <yinghai@kernel.org> [2008-12-24 12:34:41]:
> > > > >
> > > > >> --
> > > > >
> > > > > After the applying the patch, the kernel panic's with the same backtrace. The
> > > > > box is running Fedora 5 on it.
> > > > >
> > > >
> > > > please try...
> > > > Ingo, do we need to switch to use #idef and inline function instead?
> > >
> > > I recall David Howells had a similar issue with the bootparamter patch set.
> > > The workaround he used was to add a barrier(); call in the weak function
> > > to avoid the inline.
> > >
> > > [full context kept as I added David to to: list].
> > > Sam
> > >
> >
> > Hi Yinghai,
> >
> > Thanks, after applying the patch, the kernel boot's up fine.
>
> how about the patch below, does that work too? (after removing Yinghai's
> patch)
>
> Ingo

Hi Ingo,

Kernel crashes with the same trace, after the applying the patch.

>
> ------------->
> From 0d41e654c877a0de441448ca2f63a72ed11c5d84 Mon Sep 17 00:00:00 2001
> From: Ingo Molnar <mingo@elte.hu>
> Date: Fri, 26 Dec 2008 14:39:51 +0100
> Subject: [PATCH] kbuild, sparseirq: work around GCC bug with __weak aliases
>
> Impact: fix panic on null pointer with sparseirq
>
> Certain versions of GCC inline the weak global functions.
> Work it around by marking __weak functions as noinline.
>
> Signed-off-by: Ingo Molnar <mingo@elte.hu>
> ---
> include/linux/compiler-gcc.h | 8 +++++++-
> 1 files changed, 7 insertions(+), 1 deletions(-)
>
> diff --git a/include/linux/compiler-gcc.h b/include/linux/compiler-gcc.h
> index 5c8351b..1ad72e6 100644
> --- a/include/linux/compiler-gcc.h
> +++ b/include/linux/compiler-gcc.h
> @@ -41,11 +41,17 @@
>
> #define __deprecated __attribute__((deprecated))
> #define __packed __attribute__((packed))
> -#define __weak __attribute__((weak))
> #define __naked __attribute__((naked))
> #define __noreturn __attribute__((noreturn))
>
> /*
> + * Mark weak aliases also noinline, because some GCC versions
> + * incorrectly inline weak aliases (even when a non-weak variant
> + * is there) and thus cause crashes:
> + */
> +#define __weak __attribute__((weak)) noinline
> +
> +/*
> * From the GCC manual:
> *
> * Many functions have no effects except the return value and their
> --
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--
Thanks & Regards,
Kamalesh Babulal,
Linux Technology Center,
IBM, ISTL.