Re: include/linux/huge_mm.h:285:undefined reference to `mthp_stats'

[Barry Song]

> tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
> head:   c760b3725e52403dc1b28644fb09c47a83cacea6
> commit: ec33687c674934dfefd782a8ffd58370b080b503 mm: add per-order mTHP anon_fault_alloc and anon_fault_fallback counters
> date:   2 weeks ago
> config: s390-randconfig-r005-20230226 (https://download.01.org/0day-ci/archive/20240523/202405231728.tCAogiSI-lkp@xxxxxxxxx/config)
> compiler: s390-linux-gcc (GCC) 13.2.0
> reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240523/202405231728.tCAogiSI-lkp@xxxxxxxxx/reproduce)

> If you fix the issue in a separate patch/commit (i.e. not just a new version of
> the same patch/commit), kindly add following tags
> | Reported-by: kernel test robot <lkp@xxxxxxxxx>
> | Closes: https://lore.kernel.org/oe-kbuild-all/202405231728.tCAogiSI-lkp@xxxxxxxxx/
> 
> All errors (new ones prefixed by >>):
> 
>    s390-linux-ld: mm/memory.o: in function `count_mthp_stat':
>>> include/linux/huge_mm.h:285:(.text+0x191c): undefined reference to `mthp_stats'
>    s390-linux-ld: mm/huge_memory.o:(.rodata+0x10): undefined reference to `mthp_stats'
> 
> 
> vim +285 include/linux/huge_mm.h
> 
>    279	
>    280	static inline void count_mthp_stat(int order, enum mthp_stat_item item)
>    281	{
>    282		if (order <= 0 || order > PMD_ORDER)
>    283			return;
>    284	
>>   285		this_cpu_inc(mthp_stats.stats[order][item]);
>    286	}
>    287	

Thanks, would you please test if the below patch fixes the problem,

From: Barry Song <v-songbaohua@xxxxxxxx>
Date: Fri, 24 May 2024 08:50:48 +1200
Subject: [PATCH] mm: huge_mm: fix undefined reference to `mthp_stats' for
 CONFIG_SYSFS=n

if CONFIG_SYSFS is not enabled in config, we get the below error,

All errors (new ones prefixed by >>):

   s390-linux-ld: mm/memory.o: in function `count_mthp_stat':
>> include/linux/huge_mm.h:285:(.text+0x191c): undefined reference to `mthp_stats'
   s390-linux-ld: mm/huge_memory.o:(.rodata+0x10): undefined reference to `mthp_stats'

vim +285 include/linux/huge_mm.h

   279
   280  static inline void count_mthp_stat(int order, enum mthp_stat_item item)
   281  {
   282          if (order <= 0 || order > PMD_ORDER)
   283                  return;
   284
 > 285          this_cpu_inc(mthp_stats.stats[order][item]);
   286  }
   287

Reported-by: kernel test robot <lkp@xxxxxxxxx>
Closes: https://lore.kernel.org/oe-kbuild-all/202405231728.tCAogiSI-lkp@xxxxxxxxx/
Signed-off-by: Barry Song <v-songbaohua@xxxxxxxx>
---
 include/linux/huge_mm.h | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
index c8d3ec116e29..09c5744d9124 100644
--- a/include/linux/huge_mm.h
+++ b/include/linux/huge_mm.h
@@ -278,6 +278,7 @@ struct mthp_stat {
 	unsigned long stats[ilog2(MAX_PTRS_PER_PTE) + 1][__MTHP_STAT_COUNT];
 };
 
+#ifdef CONFIG_SYSFS
 DECLARE_PER_CPU(struct mthp_stat, mthp_stats);
 
 static inline void count_mthp_stat(int order, enum mthp_stat_item item)
@@ -287,6 +288,11 @@ static inline void count_mthp_stat(int order, enum mthp_stat_item item)
 
 	this_cpu_inc(mthp_stats.stats[order][item]);
 }
+#else
+static inline void count_mthp_stat(int order, enum mthp_stat_item item)
+{
+}
+#endif
 
 #define transparent_hugepage_use_zero_page()				\
 	(transparent_hugepage_flags &					\
-- 
2.34.1