[vbabka:slab-fms-cleanup 2/4] mm/slab.h:107:15: error: static assertion failed due to requirement 'sizeof(struct slab) <= sizeof(struct page)': sizeof(struct slab) <= sizeof(struct page)

[vbabka:slab-fms-cleanup 2/4] mm/slab.h:107:15: error: static assertion failed due to requirement 'sizeof(struct slab) <= sizeof(struct page)': sizeof(struct slab) <= sizeof(struct page)

[kernel test robot]

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/vbabka/linux.git slab-fms-cleanup
head:   e401df7388463ed094dca0ba9c7bac58b1ee4cc7
commit: 382037dcfead97fb0a66368b8237220a7f4a661b [2/4] slab: move counters union to freelist_aba_t
config: loongarch-allnoconfig (https://download.01.org/0day-ci/archive/20251105/202511050409.LJTnpEfF-lkp@intel.com/config)
compiler: clang version 22.0.0git (https://github.com/llvm/llvm-project d2625a438020ad35330cda29c3def102c1687b1b)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20251105/202511050409.LJTnpEfF-lkp@intel.com/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@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202511050409.LJTnpEfF-lkp@intel.com/

All errors (new ones prefixed by >>):

   In file included from mm/mempool.c:21:
>> mm/slab.h:107:15: error: static assertion failed due to requirement 'sizeof(struct slab) <= sizeof(struct page)': sizeof(struct slab) <= sizeof(struct page)
     107 | static_assert(sizeof(struct slab) <= sizeof(struct page));
         |               ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   include/linux/build_bug.h:77:50: note: expanded from macro 'static_assert'
      77 | #define static_assert(expr, ...) __static_assert(expr, ##__VA_ARGS__, #expr)
         |                                                  ^~~~
   include/linux/build_bug.h:78:56: note: expanded from macro '__static_assert'
      78 | #define __static_assert(expr, msg, ...) _Static_assert(expr, msg)
         |                                                        ^~~~
   mm/slab.h:107:35: note: expression evaluates to '64 <= 56'
     107 | static_assert(sizeof(struct slab) <= sizeof(struct page));
         |               ~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~
   include/linux/build_bug.h:77:50: note: expanded from macro 'static_assert'
      77 | #define static_assert(expr, ...) __static_assert(expr, ##__VA_ARGS__, #expr)
         |                                                  ^~~~
   include/linux/build_bug.h:78:56: note: expanded from macro '__static_assert'
      78 | #define __static_assert(expr, msg, ...) _Static_assert(expr, msg)
         |                                                        ^~~~
   1 error generated.


vim +107 mm/slab.h

d122019bf061cc Matthew Wilcox (Oracle  2021-10-04   95) 
d122019bf061cc Matthew Wilcox (Oracle  2021-10-04   96) #define SLAB_MATCH(pg, sl)						\
d122019bf061cc Matthew Wilcox (Oracle  2021-10-04   97) 	static_assert(offsetof(struct page, pg) == offsetof(struct slab, sl))
30908096dd8d79 Matthew Wilcox (Oracle  2025-06-11   98) SLAB_MATCH(flags, flags);
130d4df57390a2 Vlastimil Babka         2022-08-26   99  SLAB_MATCH(compound_head, slab_cache);	/* Ensure bit 0 is clear */
d122019bf061cc Matthew Wilcox (Oracle  2021-10-04  100) SLAB_MATCH(_refcount, __page_refcount);
a52c6330ff2fe1 Alex Shi (Tencent       2024-07-12  101) #ifdef CONFIG_MEMCG
21c690a349baab Suren Baghdasaryan      2024-03-21  102  SLAB_MATCH(memcg_data, obj_exts);
a52c6330ff2fe1 Alex Shi (Tencent       2024-07-12  103) #elif defined(CONFIG_SLAB_OBJ_EXT)
a52c6330ff2fe1 Alex Shi (Tencent       2024-07-12  104) SLAB_MATCH(_unused_slab_obj_exts, obj_exts);
d122019bf061cc Matthew Wilcox (Oracle  2021-10-04  105) #endif
d122019bf061cc Matthew Wilcox (Oracle  2021-10-04  106) #undef SLAB_MATCH
d122019bf061cc Matthew Wilcox (Oracle  2021-10-04 @107) static_assert(sizeof(struct slab) <= sizeof(struct page));
a9e0b9f27266d4 Vlastimil Babka         2023-10-02  108  #if defined(system_has_freelist_aba)
6801be4f2653e5 Peter Zijlstra          2023-05-31  109  static_assert(IS_ALIGNED(offsetof(struct slab, freelist), sizeof(freelist_aba_t)));
130d4df57390a2 Vlastimil Babka         2022-08-26  110  #endif
d122019bf061cc Matthew Wilcox (Oracle  2021-10-04  111) 

:::::: The code at line 107 was first introduced by commit
:::::: d122019bf061cccc4583eb9ad40bf58c2fe517be mm: Split slab into its own type

:::::: TO: Matthew Wilcox (Oracle) <willy@infradead.org>
:::::: CC: Vlastimil Babka <vbabka@suse.cz>

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