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Message-ID: <202307041252.XCQcx0eb-lkp@intel.com>
Date: Tue, 4 Jul 2023 12:15:03 +0800
From: kernel test robot <lkp@...el.com>
To: Matteo Rizzo <matteorizzo@...gle.com>, linux-mm@...ck.org,
linux-kernel@...r.kernel.org, cl@...ux.com, penberg@...nel.org,
rientjes@...gle.com, iamjoonsoo.kim@....com,
akpm@...ux-foundation.org, vbabka@...e.cz
Cc: llvm@...ts.linux.dev, oe-kbuild-all@...ts.linux.dev,
roman.gushchin@...ux.dev, 42.hyeyoo@...il.com, jannh@...gle.com,
matteorizzo@...gle.com
Subject: Re: [PATCH] mm/slub: refactor freelist to use custom type
Hi Matteo,
kernel test robot noticed the following build errors:
[auto build test ERROR on a901a3568fd26ca9c4a82d8bc5ed5b3ed844d451]
url: https://github.com/intel-lab-lkp/linux/commits/Matteo-Rizzo/mm-slub-refactor-freelist-to-use-custom-type/20230703-223944
base: a901a3568fd26ca9c4a82d8bc5ed5b3ed844d451
patch link: https://lore.kernel.org/r/20230703143820.152479-1-matteorizzo%40google.com
patch subject: [PATCH] mm/slub: refactor freelist to use custom type
config: arm-randconfig-r001-20230703 (https://download.01.org/0day-ci/archive/20230704/202307041252.XCQcx0eb-lkp@intel.com/config)
compiler: clang version 15.0.7 (https://github.com/llvm/llvm-project.git 8dfdcc7b7bf66834a761bd8de445840ef68e4d1a)
reproduce: (https://download.01.org/0day-ci/archive/20230704/202307041252.XCQcx0eb-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@...el.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202307041252.XCQcx0eb-lkp@intel.com/
All errors (new ones prefixed by >>):
mm/slub.c:368:15: error: unknown type name 'freeptr_t'
static inline freeptr_t freelist_ptr_encode(const struct kmem_cache *s,
^
>> mm/slub.c:385:10: error: use of undeclared identifier 'freeptr_t'
return (freeptr_t){.v = (unsigned long)ptr};
^
mm/slub.c:390:6: error: unknown type name 'freeptr_t'
freeptr_t ptr, unsigned long ptr_addr)
^
>> mm/slub.c:408:45: error: expected expression
return freelist_ptr_decode(s, *(freeptr_t *)(ptr_addr),
^
mm/slub.c:408:34: error: use of undeclared identifier 'freeptr_t'
return freelist_ptr_decode(s, *(freeptr_t *)(ptr_addr),
^
mm/slub.c:415:45: error: expected expression
return freelist_dereference(s, (freeptr_t *)(object + s->offset));
^
mm/slub.c:415:34: error: use of undeclared identifier 'freeptr_t'
return freelist_dereference(s, (freeptr_t *)(object + s->offset));
^
mm/slub.c:439:2: error: use of undeclared identifier 'freeptr_t'
freeptr_t p;
^
mm/slub.c:446:43: error: expected expression
copy_from_kernel_nofault(&p, (freeptr_t *)freepointer_addr, sizeof(p));
^
mm/slub.c:446:32: error: use of undeclared identifier 'freeptr_t'
copy_from_kernel_nofault(&p, (freeptr_t *)freepointer_addr, sizeof(p));
^
>> mm/slub.c:446:69: error: use of undeclared identifier 'p'
copy_from_kernel_nofault(&p, (freeptr_t *)freepointer_addr, sizeof(p));
^
mm/slub.c:446:28: error: use of undeclared identifier 'p'
copy_from_kernel_nofault(&p, (freeptr_t *)freepointer_addr, sizeof(p));
^
mm/slub.c:447:32: error: use of undeclared identifier 'p'
return freelist_ptr_decode(s, p, freepointer_addr);
^
mm/slub.c:459:15: error: expected expression
*(freeptr_t *)freeptr_addr = freelist_ptr_encode(s, fp, freeptr_addr);
^
mm/slub.c:459:4: error: use of undeclared identifier 'freeptr_t'
*(freeptr_t *)freeptr_addr = freelist_ptr_encode(s, fp, freeptr_addr);
^
mm/slub.c:2285:15: warning: variable 'partial_slabs' set but not used [-Wunused-but-set-variable]
unsigned int partial_slabs = 0;
^
1 warning and 15 errors generated.
vim +/freeptr_t +385 mm/slub.c
358
359 /********************************************************************
360 * Core slab cache functions
361 *******************************************************************/
362
363 /*
364 * Returns freelist pointer (ptr). With hardening, this is obfuscated
365 * with an XOR of the address where the pointer is held and a per-cache
366 * random number.
367 */
> 368 static inline freeptr_t freelist_ptr_encode(const struct kmem_cache *s,
369 void *ptr, unsigned long ptr_addr)
370 {
371 #ifdef CONFIG_SLAB_FREELIST_HARDENED
372 /*
373 * When CONFIG_KASAN_SW/HW_TAGS is enabled, ptr_addr might be tagged.
374 * Normally, this doesn't cause any issues, as both set_freepointer()
375 * and get_freepointer() are called with a pointer with the same tag.
376 * However, there are some issues with CONFIG_SLUB_DEBUG code. For
377 * example, when __free_slub() iterates over objects in a cache, it
378 * passes untagged pointers to check_object(). check_object() in turns
379 * calls get_freepointer() with an untagged pointer, which causes the
380 * freepointer to be restored incorrectly.
381 */
382 return (freeptr_t){.v = (unsigned long)ptr ^ s->random ^
383 swab((unsigned long)kasan_reset_tag((void *)ptr_addr))};
384 #else
> 385 return (freeptr_t){.v = (unsigned long)ptr};
386 #endif
387 }
388
389 static inline void *freelist_ptr_decode(const struct kmem_cache *s,
390 freeptr_t ptr, unsigned long ptr_addr)
391 {
392 void *decoded;
393
394 #ifdef CONFIG_SLAB_FREELIST_HARDENED
395 /* See the comment in freelist_ptr_encode */
396 decoded = (void *)(ptr.v ^ s->random ^
397 swab((unsigned long)kasan_reset_tag((void *)ptr_addr)));
398 #else
399 decoded = (void *)ptr.v;
400 #endif
401 return decoded;
402 }
403
404 /* Returns the freelist pointer recorded at location ptr_addr. */
405 static inline void *freelist_dereference(const struct kmem_cache *s,
406 void *ptr_addr)
407 {
> 408 return freelist_ptr_decode(s, *(freeptr_t *)(ptr_addr),
409 (unsigned long)ptr_addr);
410 }
411
412 static inline void *get_freepointer(struct kmem_cache *s, void *object)
413 {
414 object = kasan_reset_tag(object);
415 return freelist_dereference(s, (freeptr_t *)(object + s->offset));
416 }
417
418 #ifndef CONFIG_SLUB_TINY
419 static void prefetch_freepointer(const struct kmem_cache *s, void *object)
420 {
421 prefetchw(object + s->offset);
422 }
423 #endif
424
425 /*
426 * When running under KMSAN, get_freepointer_safe() may return an uninitialized
427 * pointer value in the case the current thread loses the race for the next
428 * memory chunk in the freelist. In that case this_cpu_cmpxchg_double() in
429 * slab_alloc_node() will fail, so the uninitialized value won't be used, but
430 * KMSAN will still check all arguments of cmpxchg because of imperfect
431 * handling of inline assembly.
432 * To work around this problem, we apply __no_kmsan_checks to ensure that
433 * get_freepointer_safe() returns initialized memory.
434 */
435 __no_kmsan_checks
436 static inline void *get_freepointer_safe(struct kmem_cache *s, void *object)
437 {
438 unsigned long freepointer_addr;
> 439 freeptr_t p;
440
441 if (!debug_pagealloc_enabled_static())
442 return get_freepointer(s, object);
443
444 object = kasan_reset_tag(object);
445 freepointer_addr = (unsigned long)object + s->offset;
> 446 copy_from_kernel_nofault(&p, (freeptr_t *)freepointer_addr, sizeof(p));
447 return freelist_ptr_decode(s, p, freepointer_addr);
448 }
449
--
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https://github.com/intel/lkp-tests/wiki
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