Re: [PATCH] mm/slab: improve kmem_cache_alloc_bulk
From: kernel test robot
Date: Thu May 28 2026 - 05:00:12 EST
Hi Christoph,
kernel test robot noticed the following build errors:
[auto build test ERROR on akpm-mm/mm-everything]
url: https://github.com/intel-lab-lkp/linux/commits/Christoph-Hellwig/mm-slab-improve-kmem_cache_alloc_bulk/20260527-150421
base: https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-everything
patch link: https://lore.kernel.org/r/20260527070239.2252948-2-hch%40lst.de
patch subject: [PATCH] mm/slab: improve kmem_cache_alloc_bulk
config: parisc-randconfig-r071-20260528 (https://download.01.org/0day-ci/archive/20260528/202605281629.y8HhAihO-lkp@xxxxxxxxx/config)
compiler: hppa-linux-gcc (GCC) 8.5.0
smatch: v0.5.0-9185-gbcc58b9c
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260528/202605281629.y8HhAihO-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/202605281629.y8HhAihO-lkp@xxxxxxxxx/
All errors (new ones prefixed by >>):
lib/test_meminit.c: In function 'do_kmem_cache_size':
>> lib/test_meminit.c:239:29: error: 'ret' undeclared (first use in this function); did you mean 'net'?
kmem_cache_free_bulk(c, ret, bulk_array);
^~~
net
lib/test_meminit.c:239:29: note: each undeclared identifier is reported only once for each function it appears in
vim +239 lib/test_meminit.c
dc5c5ad79f0cc2d Laura Abbott 2019-12-04 209
5015a300a522c8f Alexander Potapenko 2019-07-16 210 /*
5015a300a522c8f Alexander Potapenko 2019-07-16 211 * Test kmem_cache with given parameters:
5015a300a522c8f Alexander Potapenko 2019-07-16 212 * want_ctor - use a constructor;
5015a300a522c8f Alexander Potapenko 2019-07-16 213 * want_rcu - use SLAB_TYPESAFE_BY_RCU;
5015a300a522c8f Alexander Potapenko 2019-07-16 214 * want_zero - use __GFP_ZERO.
5015a300a522c8f Alexander Potapenko 2019-07-16 215 */
5015a300a522c8f Alexander Potapenko 2019-07-16 216 static int __init do_kmem_cache_size(size_t size, bool want_ctor,
5015a300a522c8f Alexander Potapenko 2019-07-16 217 bool want_rcu, bool want_zero,
5015a300a522c8f Alexander Potapenko 2019-07-16 218 int *total_failures)
5015a300a522c8f Alexander Potapenko 2019-07-16 219 {
5015a300a522c8f Alexander Potapenko 2019-07-16 220 struct kmem_cache *c;
5015a300a522c8f Alexander Potapenko 2019-07-16 221 int iter;
5015a300a522c8f Alexander Potapenko 2019-07-16 222 bool fail = false;
5015a300a522c8f Alexander Potapenko 2019-07-16 223 gfp_t alloc_mask = GFP_KERNEL | (want_zero ? __GFP_ZERO : 0);
5015a300a522c8f Alexander Potapenko 2019-07-16 224 void *buf, *buf_copy;
5015a300a522c8f Alexander Potapenko 2019-07-16 225
5015a300a522c8f Alexander Potapenko 2019-07-16 226 c = kmem_cache_create("test_cache", size, 1,
5015a300a522c8f Alexander Potapenko 2019-07-16 227 want_rcu ? SLAB_TYPESAFE_BY_RCU : 0,
5015a300a522c8f Alexander Potapenko 2019-07-16 228 want_ctor ? test_ctor : NULL);
5015a300a522c8f Alexander Potapenko 2019-07-16 229 for (iter = 0; iter < 10; iter++) {
dc5c5ad79f0cc2d Laura Abbott 2019-12-04 230 /* Do a test of bulk allocations */
dc5c5ad79f0cc2d Laura Abbott 2019-12-04 231 if (!want_rcu && !want_ctor) {
863d4ee245fb4d6 Christoph Hellwig 2026-05-27 232 if (!kmem_cache_alloc_bulk(c, alloc_mask, BULK_SIZE,
863d4ee245fb4d6 Christoph Hellwig 2026-05-27 233 bulk_array)) {
dc5c5ad79f0cc2d Laura Abbott 2019-12-04 234 fail = true;
dc5c5ad79f0cc2d Laura Abbott 2019-12-04 235 } else {
dc5c5ad79f0cc2d Laura Abbott 2019-12-04 236 int i;
863d4ee245fb4d6 Christoph Hellwig 2026-05-27 237 for (i = 0; i < BULK_SIZE; i++)
dc5c5ad79f0cc2d Laura Abbott 2019-12-04 238 fail |= check_buf(bulk_array[i], size, want_ctor, want_rcu, want_zero);
dc5c5ad79f0cc2d Laura Abbott 2019-12-04 @239 kmem_cache_free_bulk(c, ret, bulk_array);
dc5c5ad79f0cc2d Laura Abbott 2019-12-04 240 }
dc5c5ad79f0cc2d Laura Abbott 2019-12-04 241 }
dc5c5ad79f0cc2d Laura Abbott 2019-12-04 242
5015a300a522c8f Alexander Potapenko 2019-07-16 243 buf = kmem_cache_alloc(c, alloc_mask);
5015a300a522c8f Alexander Potapenko 2019-07-16 244 /* Check that buf is zeroed, if it must be. */
dc5c5ad79f0cc2d Laura Abbott 2019-12-04 245 fail |= check_buf(buf, size, want_ctor, want_rcu, want_zero);
5015a300a522c8f Alexander Potapenko 2019-07-16 246 fill_with_garbage_skip(buf, size, want_ctor ? CTOR_BYTES : 0);
d3a811617ae629d Arnd Bergmann 2019-07-16 247
d3a811617ae629d Arnd Bergmann 2019-07-16 248 if (!want_rcu) {
d3a811617ae629d Arnd Bergmann 2019-07-16 249 kmem_cache_free(c, buf);
d3a811617ae629d Arnd Bergmann 2019-07-16 250 continue;
d3a811617ae629d Arnd Bergmann 2019-07-16 251 }
d3a811617ae629d Arnd Bergmann 2019-07-16 252
5015a300a522c8f Alexander Potapenko 2019-07-16 253 /*
5015a300a522c8f Alexander Potapenko 2019-07-16 254 * If this is an RCU cache, use a critical section to ensure we
5015a300a522c8f Alexander Potapenko 2019-07-16 255 * can touch objects after they're freed.
5015a300a522c8f Alexander Potapenko 2019-07-16 256 */
5015a300a522c8f Alexander Potapenko 2019-07-16 257 rcu_read_lock();
5015a300a522c8f Alexander Potapenko 2019-07-16 258 /*
5015a300a522c8f Alexander Potapenko 2019-07-16 259 * Copy the buffer to check that it's not wiped on
5015a300a522c8f Alexander Potapenko 2019-07-16 260 * free().
5015a300a522c8f Alexander Potapenko 2019-07-16 261 */
733d1d1a7745113 Alexander Potapenko 2019-08-02 262 buf_copy = kmalloc(size, GFP_ATOMIC);
5015a300a522c8f Alexander Potapenko 2019-07-16 263 if (buf_copy)
5015a300a522c8f Alexander Potapenko 2019-07-16 264 memcpy(buf_copy, buf, size);
d3a811617ae629d Arnd Bergmann 2019-07-16 265
4ab7ace465466d2 Alexander Potapenko 2019-07-16 266 kmem_cache_free(c, buf);
5015a300a522c8f Alexander Potapenko 2019-07-16 267 /*
5015a300a522c8f Alexander Potapenko 2019-07-16 268 * Check that |buf| is intact after kmem_cache_free().
5015a300a522c8f Alexander Potapenko 2019-07-16 269 * |want_zero| is false, because we wrote garbage to
5015a300a522c8f Alexander Potapenko 2019-07-16 270 * the buffer already.
5015a300a522c8f Alexander Potapenko 2019-07-16 271 */
5015a300a522c8f Alexander Potapenko 2019-07-16 272 fail |= check_buf(buf, size, want_ctor, want_rcu,
5015a300a522c8f Alexander Potapenko 2019-07-16 273 false);
5015a300a522c8f Alexander Potapenko 2019-07-16 274 if (buf_copy) {
5015a300a522c8f Alexander Potapenko 2019-07-16 275 fail |= (bool)memcmp(buf, buf_copy, size);
5015a300a522c8f Alexander Potapenko 2019-07-16 276 kfree(buf_copy);
5015a300a522c8f Alexander Potapenko 2019-07-16 277 }
5015a300a522c8f Alexander Potapenko 2019-07-16 278 rcu_read_unlock();
5015a300a522c8f Alexander Potapenko 2019-07-16 279 }
5015a300a522c8f Alexander Potapenko 2019-07-16 280 kmem_cache_destroy(c);
5015a300a522c8f Alexander Potapenko 2019-07-16 281
5015a300a522c8f Alexander Potapenko 2019-07-16 282 *total_failures += fail;
5015a300a522c8f Alexander Potapenko 2019-07-16 283 return 1;
5015a300a522c8f Alexander Potapenko 2019-07-16 284 }
5015a300a522c8f Alexander Potapenko 2019-07-16 285
--
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