* Re: [PATCH v3 1/4] cpumask: Fix invalid uniprocessor mask assumption
[not found] <cc1f7d3334348cccbf9fde091015a802f379a9be.1654410109.git.sander@svanheule.net>
@ 2022-06-06 0:48 ` kernel test robot
2022-06-06 10:40 ` Andy Shevchenko
0 siblings, 1 reply; 3+ messages in thread
From: kernel test robot @ 2022-06-06 0:48 UTC (permalink / raw)
To: Sander Vanheule, Peter Zijlstra, Yury Norov, Andrew Morton,
Valentin Schneider, Thomas Gleixner, Greg Kroah-Hartman,
Marco Elver
Cc: kbuild-all, Linux Memory Management List, linux-kernel,
Andy Shevchenko, Sander Vanheule
Hi Sander,
I love your patch! Yet something to improve:
[auto build test ERROR on akpm-mm/mm-everything]
[also build test ERROR on linus/master v5.18 next-20220603]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]
url: https://github.com/intel-lab-lkp/linux/commits/Sander-Vanheule/cpumask-Fix-invalid-uniprocessor-assumptions/20220606-004959
base: https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-everything
config: i386-randconfig-a009 (https://download.01.org/0day-ci/archive/20220606/202206060858.wA0FOzRy-lkp@intel.com/config)
compiler: gcc-11 (Debian 11.3.0-1) 11.3.0
reproduce (this is a W=1 build):
# https://github.com/intel-lab-lkp/linux/commit/37b3f10c4604ea299b454f39ac5ba3cad903ae16
git remote add linux-review https://github.com/intel-lab-lkp/linux
git fetch --no-tags linux-review Sander-Vanheule/cpumask-Fix-invalid-uniprocessor-assumptions/20220606-004959
git checkout 37b3f10c4604ea299b454f39ac5ba3cad903ae16
# save the config file
mkdir build_dir && cp config build_dir/.config
make W=1 O=build_dir ARCH=i386 SHELL=/bin/bash
If you fix the issue, kindly add following tag where applicable
Reported-by: kernel test robot <lkp@intel.com>
All errors (new ones prefixed by >>):
ld: arch/x86/kernel/cpu/cacheinfo.o: in function `__cache_amd_cpumap_setup':
arch/x86/kernel/cpu/cacheinfo.c:890: undefined reference to `cpu_llc_shared_map'
>> ld: arch/x86/kernel/cpu/cacheinfo.c:895: undefined reference to `cpu_llc_shared_map'
--
0-DAY CI Kernel Test Service
https://01.org/lkp
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH v3 1/4] cpumask: Fix invalid uniprocessor mask assumption
2022-06-06 0:48 ` [PATCH v3 1/4] cpumask: Fix invalid uniprocessor mask assumption kernel test robot
@ 2022-06-06 10:40 ` Andy Shevchenko
2022-06-08 17:59 ` Sander Vanheule
0 siblings, 1 reply; 3+ messages in thread
From: Andy Shevchenko @ 2022-06-06 10:40 UTC (permalink / raw)
To: kernel test robot
Cc: Sander Vanheule, Peter Zijlstra, Yury Norov, Andrew Morton,
Valentin Schneider, Thomas Gleixner, Greg Kroah-Hartman,
Marco Elver, kbuild-all, Linux Memory Management List,
linux-kernel
On Mon, Jun 06, 2022 at 08:48:05AM +0800, kernel test robot wrote:
> Hi Sander,
>
> I love your patch! Yet something to improve:
>
> [auto build test ERROR on akpm-mm/mm-everything]
> [also build test ERROR on linus/master v5.18 next-20220603]
> [If your patch is applied to the wrong git tree, kindly drop us a note.
> And when submitting patch, we suggest to use '--base' as documented in
> https://git-scm.com/docs/git-format-patch]
>
> url: https://github.com/intel-lab-lkp/linux/commits/Sander-Vanheule/cpumask-Fix-invalid-uniprocessor-assumptions/20220606-004959
> base: https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-everything
> config: i386-randconfig-a009 (https://download.01.org/0day-ci/archive/20220606/202206060858.wA0FOzRy-lkp@intel.com/config)
> compiler: gcc-11 (Debian 11.3.0-1) 11.3.0
> reproduce (this is a W=1 build):
> # https://github.com/intel-lab-lkp/linux/commit/37b3f10c4604ea299b454f39ac5ba3cad903ae16
> git remote add linux-review https://github.com/intel-lab-lkp/linux
> git fetch --no-tags linux-review Sander-Vanheule/cpumask-Fix-invalid-uniprocessor-assumptions/20220606-004959
> git checkout 37b3f10c4604ea299b454f39ac5ba3cad903ae16
> # save the config file
> mkdir build_dir && cp config build_dir/.config
> make W=1 O=build_dir ARCH=i386 SHELL=/bin/bash
>
> If you fix the issue, kindly add following tag where applicable
> Reported-by: kernel test robot <lkp@intel.com>
>
> All errors (new ones prefixed by >>):
>
> ld: arch/x86/kernel/cpu/cacheinfo.o: in function `__cache_amd_cpumap_setup':
> arch/x86/kernel/cpu/cacheinfo.c:890: undefined reference to `cpu_llc_shared_map'
> >> ld: arch/x86/kernel/cpu/cacheinfo.c:895: undefined reference to `cpu_llc_shared_map'
Seems like somewhere we need stubs for UP builds for those cache related functions.
--
With Best Regards,
Andy Shevchenko
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH v3 1/4] cpumask: Fix invalid uniprocessor mask assumption
2022-06-06 10:40 ` Andy Shevchenko
@ 2022-06-08 17:59 ` Sander Vanheule
0 siblings, 0 replies; 3+ messages in thread
From: Sander Vanheule @ 2022-06-08 17:59 UTC (permalink / raw)
To: Andy Shevchenko, kernel test robot
Cc: Peter Zijlstra, Yury Norov, Andrew Morton, Valentin Schneider,
Thomas Gleixner, Greg Kroah-Hartman, Marco Elver, kbuild-all,
Linux Memory Management List, linux-kernel
On Mon, 2022-06-06 at 13:40 +0300, Andy Shevchenko wrote:
> On Mon, Jun 06, 2022 at 08:48:05AM +0800, kernel test robot wrote:
> > Hi Sander,
> >
> > I love your patch! Yet something to improve:
> >
> > [auto build test ERROR on akpm-mm/mm-everything]
> > [also build test ERROR on linus/master v5.18 next-20220603]
> > [If your patch is applied to the wrong git tree, kindly drop us a note.
> > And when submitting patch, we suggest to use '--base' as documented in
> > https://git-scm.com/docs/git-format-patch]
> >
> > url:
> > https://github.com/intel-lab-lkp/linux/commits/Sander-Vanheule/cpumask-Fix-invalid-uniprocessor-assumptions/20220606-004959
> > base: https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-everything
> > config: i386-randconfig-a009
> > (https://download.01.org/0day-ci/archive/20220606/202206060858.wA0FOzRy-lkp@intel.com/config)
> > compiler: gcc-11 (Debian 11.3.0-1) 11.3.0
> > reproduce (this is a W=1 build):
> > # https://github.com/intel-lab-lkp/linux/commit/37b3f10c4604ea299b454f39ac5ba3cad903ae16
> > git remote add linux-review https://github.com/intel-lab-lkp/linux
> > git fetch --no-tags linux-review Sander-Vanheule/cpumask-Fix-invalid-uniprocessor-
> > assumptions/20220606-004959
> > git checkout 37b3f10c4604ea299b454f39ac5ba3cad903ae16
> > # save the config file
> > mkdir build_dir && cp config build_dir/.config
> > make W=1 O=build_dir ARCH=i386 SHELL=/bin/bash
> >
> > If you fix the issue, kindly add following tag where applicable
> > Reported-by: kernel test robot <lkp@intel.com>
> >
> > All errors (new ones prefixed by >>):
> >
> > ld: arch/x86/kernel/cpu/cacheinfo.o: in function `__cache_amd_cpumap_setup':
> > arch/x86/kernel/cpu/cacheinfo.c:890: undefined reference to `cpu_llc_shared_map'
> > > > ld: arch/x86/kernel/cpu/cacheinfo.c:895: undefined reference to `cpu_llc_shared_map'
>
> Seems like somewhere we need stubs for UP builds for those cache related functions.
>
I think I finally figured out what's going on here.
cpu_llc_shared_map is always declared with DECLARE_PER_CPU_READ_MOSTLY, but defined in
arch/x86/kernel/smpboot.c which only builds on CONFIG_SMP=y.
cpu_llc_shared_map is accessed in a for_each_cpu loop:
for_each_cpu(i, cpu_llc_shared_mask(cpu))
The old (wrong) UP implementation would ignore the mask, so cpu_llc_shared_map access was optimised
out and the linker would never see that symbol.
Adding a stub for the two inline functions in arch/x86/include/smp.h won't be sufficient I'm afraid.
But I think we can safely make the following assumptions (nobody complained before):
* anything using cpumask_first_zero(), cpumask_next_zero(), and for_each_cpu_not() was expecting an
empty mask on UP builds,
* anything else would have expected a filled mask on UP builds.
I'll think about how to identify all the possible cases, but may not be able to spend a lot of time
on this in the two coming weeks. Any suggestions, or alternative solutions, are of course welcome.
Best,
Sander
^ permalink raw reply [flat|nested] 3+ messages in thread
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2022-06-06 0:48 ` [PATCH v3 1/4] cpumask: Fix invalid uniprocessor mask assumption kernel test robot
2022-06-06 10:40 ` Andy Shevchenko
2022-06-08 17:59 ` Sander Vanheule
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