Re: mmotm 2009-04-24-18-14 uploaded - NVidia indigestion

[Nick Piggin]

On Fri, Apr 24, 2009 at 11:06:40PM -0400, Valdis.Kletnieks@xxxxxx wrote:
> On Fri, 24 Apr 2009 18:14:22 PDT, akpm@xxxxxxxxxxxxxxxxxxxx said:
> > The mm-of-the-moment snapshot 2009-04-24-18-14 has been uploaded to
> > 
> >    http://userweb.kernel.org/~akpm/mmotm/
> 
> This jumped out and asked if I wanted SLQB as the default allocator (even
> though I've had SLAB defined for ages).  I said to myself "what the heck"
> and accepted the change...

Heh, it was a sneaky trick to get more testing before merging. Worked
well :)

 
> Tried to build the NVidia binary, and it choked during config on something
> that will likely give a *lot* of programs indigestion.
> 
> The test program:
> 
> #include <linux/autoconf.h>
>     #if defined(CONFIG_XEN) &&         defined(CONFIG_XEN_INTERFACE_VERSION) &&  !defined(__XEN_INTERFACE_VERSION__)
>     #define __XEN_INTERFACE_VERSION__ CONFIG_XEN_INTERFACE_VERSION
>     #endif
>             #include <linux/version.h>
>             #include <linux/utsname.h>
>             int main() {
>               if (LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,0)) {
>                 return 0;
>               } else {
>                 return 1;
>               }
>             }
> 
> The command line:
> 
> cc -D__KERNEL__ -DKBUILD_BASENAME="#conftest23112" -DKBUILD_MODNAME="#conftest23112" -nostdinc -isystem /usr/lib/gcc/x86_64-redhat-linux/4.4.0/include -I/lib/modules/2.6.30-rc3-mmotm0424/source/include/asm-x86_64/mach-default -I/lib/modules/2.6.30-rc3-mmotm0424/source/include/asm-x86/mach-default -I/lib/modules/2.6.30-rc3-mmotm0424/source/arch/x86/include/asm/mach-default -I/lib/modules/2.6.30-rc3-mmotm0424/build/include2 -I/lib/modules/2.6.30-rc3-mmotm0424/build/include -I/lib/modules/2.6.30-rc3-mmotm0424/source/include -I/lib/modules/2.6.30-rc3-mmotm0424/source/arch/x86/include -o conftest23112 conftest23112.c
> 
> and the joy it got me:
> 
> In file included from /lib/modules/2.6.30-rc3-mmotm0424/build/include/linux/slab.h:161,
>                  from /lib/modules/2.6.30-rc3-mmotm0424/build/include/linux/percpu.h:5,
>                  from /lib/modules/2.6.30-rc3-mmotm0424/build/include/linux/sched.h:76,
>                  from /lib/modules/2.6.30-rc3-mmotm0424/build/include/linux/utsname.h:35,
>                  from conftest2465.c:6:
> /lib/modules/2.6.30-rc3-mmotm0424/build/include/linux/slqb_def.h: In function ???kmalloc_slab???:
> /lib/modules/2.6.30-rc3-mmotm0424/build/include/linux/slqb_def.h:240: error: size of array ???type name??? is negative
> 
> Why does utsname.h care about SLAB versus SLUB?  (Looks to me like somebody
> forgot to add a #include to slqb_def.h for all the headers it needed, and
> it choked.  Interestingly enough, line 240 reads:
> 
>         BUILD_BUG_ON(!__builtin_constant_p(size));
> 
> but I didn't think this was the way BUILD_BUG_ON worked?

Yeah BUILD_BUG_ON does work like that. I can't for the life of me
understand why it triggered though. Is anything in your external
code calling kmalloc_slab directly?

What's the preprocessor output look like?

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