[vbabka-slab:slab/for-7.0/obj_metadata 8/10] mm/slub.c:904 need_slab_obj_exts() warn: bitwise AND condition is false here

[vbabka-slab:slab/for-7.0/obj_metadata 8/10] mm/slub.c:904 need_slab_obj_exts() warn: bitwise AND condition is false here

[kernel test robot]

BCC: lkp@intel.com
CC: oe-kbuild-all@lists.linux.dev
CC: linux-mm@kvack.org
TO: Harry Yoo <harry.yoo@oracle.com>
CC: Vlastimil Babka <vbabka@suse.cz>

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/vbabka/slab.git slab/for-7.0/obj_metadata
head:   6edcc2867ee1ba95ae6c7695d66124bfdf0771a1
commit: 4fad56bdb6b4c4bc0ea2d919df1ae4eef7b69919 [8/10] mm/slab: save memory by allocating slabobj_ext array from leftover
:::::: branch date: 11 hours ago
:::::: commit date: 11 hours ago
config: nios2-randconfig-r072-20260119 (https://download.01.org/0day-ci/archive/20260120/202601200218.2dRYmU4Q-lkp@intel.com/config)
compiler: nios2-linux-gcc (GCC) 11.5.0
smatch version: v0.5.0-8985-g2614ff1a

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>
| Reported-by: Dan Carpenter <error27@gmail.com>
| Closes: https://lore.kernel.org/r/202601200218.2dRYmU4Q-lkp@intel.com/

New smatch warnings:
mm/slub.c:904 need_slab_obj_exts() warn: bitwise AND condition is false here

Old smatch warnings:
arch/nios2/include/asm/thread_info.h:62 current_thread_info() error: uninitialized symbol 'sp'.

vim +904 mm/slub.c

4fad56bdb6b4c4b Harry Yoo 2026-01-13  890  
4fad56bdb6b4c4b Harry Yoo 2026-01-13  891  /*
4fad56bdb6b4c4b Harry Yoo 2026-01-13  892   * Check if memory cgroup or memory allocation profiling is enabled.
4fad56bdb6b4c4b Harry Yoo 2026-01-13  893   * If enabled, SLUB tries to reduce memory overhead of accounting
4fad56bdb6b4c4b Harry Yoo 2026-01-13  894   * slab objects. If neither is enabled when this function is called,
4fad56bdb6b4c4b Harry Yoo 2026-01-13  895   * the optimization is simply skipped to avoid affecting caches that do not
4fad56bdb6b4c4b Harry Yoo 2026-01-13  896   * need slabobj_ext metadata.
4fad56bdb6b4c4b Harry Yoo 2026-01-13  897   *
4fad56bdb6b4c4b Harry Yoo 2026-01-13  898   * However, this may disable optimization when memory cgroup or memory
4fad56bdb6b4c4b Harry Yoo 2026-01-13  899   * allocation profiling is used, but slabs are created too early
4fad56bdb6b4c4b Harry Yoo 2026-01-13  900   * even before those subsystems are initialized.
4fad56bdb6b4c4b Harry Yoo 2026-01-13  901   */
4fad56bdb6b4c4b Harry Yoo 2026-01-13  902  static inline bool need_slab_obj_exts(struct kmem_cache *s)
4fad56bdb6b4c4b Harry Yoo 2026-01-13  903  {
4fad56bdb6b4c4b Harry Yoo 2026-01-13 @904  	if (memcg_kmem_online() && (s->flags & SLAB_ACCOUNT))
4fad56bdb6b4c4b Harry Yoo 2026-01-13  905  		return true;
4fad56bdb6b4c4b Harry Yoo 2026-01-13  906  
4fad56bdb6b4c4b Harry Yoo 2026-01-13  907  	if (mem_alloc_profiling_enabled())
4fad56bdb6b4c4b Harry Yoo 2026-01-13  908  		return true;
4fad56bdb6b4c4b Harry Yoo 2026-01-13  909  
4fad56bdb6b4c4b Harry Yoo 2026-01-13  910  	return false;
4fad56bdb6b4c4b Harry Yoo 2026-01-13  911  }
4fad56bdb6b4c4b Harry Yoo 2026-01-13  912  

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