Re: [PATCH] mm: slub: Panic if the object corruption is checked.

[kernel test robot]

Hi Hyesoo,

kernel test robot noticed the following build warnings:

[auto build test WARNING on akpm-mm/mm-everything]

url:    https://github.com/intel-lab-lkp/linux/commits/Hyesoo-Yu/mm-slub-Panic-if-the-object-corruption-is-checked/20250120-163233
base:   https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-everything
patch link:    https://lore.kernel.org/r/20250120082908.4162780-1-hyesoo.yu%40samsung.com
patch subject: [PATCH] mm: slub: Panic if the object corruption is checked.
config: mips-randconfig-r111-20250121 (https://download.01.org/0day-ci/archive/20250121/202501212026.lUnLNhv6-lkp@xxxxxxxxx/config)
compiler: mips-linux-gcc (GCC) 14.2.0
reproduce: (https://download.01.org/0day-ci/archive/20250121/202501212026.lUnLNhv6-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/202501212026.lUnLNhv6-lkp@xxxxxxxxx/

sparse warnings: (new ones prefixed by >>)
>> mm/slub.c:1308:9: sparse: sparse: cast from restricted slab_flags_t
   mm/slub.c:1394:17: sparse: sparse: cast from restricted slab_flags_t
   mm/slub.c:4440:47: sparse: sparse: context imbalance in '__slab_free' - unexpected unlock

vim +1308 mm/slub.c

  1273	
  1274	/* Check the pad bytes at the end of a slab page */
  1275	static pad_check_attributes void
  1276	slab_pad_check(struct kmem_cache *s, struct slab *slab)
  1277	{
  1278		u8 *start;
  1279		u8 *fault;
  1280		u8 *end;
  1281		u8 *pad;
  1282		int length;
  1283		int remainder;
  1284	
  1285		if (!(s->flags & SLAB_POISON))
  1286			return;
  1287	
  1288		start = slab_address(slab);
  1289		length = slab_size(slab);
  1290		end = start + length;
  1291		remainder = length % s->size;
  1292		if (!remainder)
  1293			return;
  1294	
  1295		pad = end - remainder;
  1296		metadata_access_enable();
  1297		fault = memchr_inv(kasan_reset_tag(pad), POISON_INUSE, remainder);
  1298		metadata_access_disable();
  1299		if (!fault)
  1300			return;
  1301		while (end > fault && end[-1] == POISON_INUSE)
  1302			end--;
  1303	
  1304		slab_err(s, slab, "Padding overwritten. 0x%p-0x%p @offset=%tu",
  1305				fault, end - 1, fault - start);
  1306		print_section(KERN_ERR, "Padding ", pad, remainder);
  1307	
> 1308		BUG_ON(s->flags & SLAB_CORRUPTION_PANIC);
  1309	
  1310		restore_bytes(s, "slab padding", POISON_INUSE, fault, end);
  1311	}
  1312	

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