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SubjectRe: [PATCH 2/2] mm: kfence: fix objcgs vector allocation
Hi Muchun,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on hnaz-mm/master]

url: https://github.com/intel-lab-lkp/linux/commits/Muchun-Song/mm-kfence-fix-missing-objcg-housekeeping-for-SLAB/20220327-132038
base: https://github.com/hnaz/linux-mm master
config: x86_64-randconfig-c022 (https://download.01.org/0day-ci/archive/20220327/202203271619.Ni4lY7Mc-lkp@intel.com/config)
compiler: gcc-9 (Ubuntu 9.4.0-1ubuntu1~20.04.1) 9.4.0
reproduce (this is a W=1 build):
# https://github.com/intel-lab-lkp/linux/commit/a33cf78311711db98d9f77541d0a4b50bc466875
git remote add linux-review https://github.com/intel-lab-lkp/linux
git fetch --no-tags linux-review Muchun-Song/mm-kfence-fix-missing-objcg-housekeeping-for-SLAB/20220327-132038
git checkout a33cf78311711db98d9f77541d0a4b50bc466875
# save the config file to linux build tree
mkdir build_dir
make W=1 O=build_dir ARCH=x86_64 SHELL=/bin/bash mm/kfence/

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>

All warnings (new ones prefixed by >>):

mm/kfence/core.c: In function 'kfence_init_pool':
>> mm/kfence/core.c:593:36: warning: passing argument 1 of 'virt_to_slab' makes pointer from integer without a cast [-Wint-conversion]
593 | struct slab *slab = virt_to_slab(addr);
| ^~~~
| |
| long unsigned int
In file included from mm/kfence/kfence.h:17,
from mm/kfence/core.c:35:
mm/kfence/../slab.h:173:53: note: expected 'const void *' but argument is of type 'long unsigned int'
173 | static inline struct slab *virt_to_slab(const void *addr)
| ~~~~~~~~~~~~^~~~
mm/kfence/core.c:597:7: error: 'struct slab' has no member named 'memcg_data'
597 | slab->memcg_data = (unsigned long)&meta->objcg | MEMCG_DATA_OBJCGS;
| ^~
mm/kfence/core.c:597:52: error: 'MEMCG_DATA_OBJCGS' undeclared (first use in this function)
597 | slab->memcg_data = (unsigned long)&meta->objcg | MEMCG_DATA_OBJCGS;
| ^~~~~~~~~~~~~~~~~
mm/kfence/core.c:597:52: note: each undeclared identifier is reported only once for each function it appears in


vim +/virt_to_slab +593 mm/kfence/core.c

543
544 /*
545 * Initialization of the KFENCE pool after its allocation.
546 * Returns 0 on success; otherwise returns the address up to
547 * which partial initialization succeeded.
548 */
549 static unsigned long kfence_init_pool(void)
550 {
551 unsigned long addr = (unsigned long)__kfence_pool;
552 struct page *pages;
553 int i;
554
555 if (!arch_kfence_init_pool())
556 return addr;
557
558 pages = virt_to_page(addr);
559
560 /*
561 * Set up object pages: they must have PG_slab set, to avoid freeing
562 * these as real pages.
563 *
564 * We also want to avoid inserting kfence_free() in the kfree()
565 * fast-path in SLUB, and therefore need to ensure kfree() correctly
566 * enters __slab_free() slow-path.
567 */
568 for (i = 0; i < KFENCE_POOL_SIZE / PAGE_SIZE; i++) {
569 if (!i || (i % 2))
570 continue;
571
572 /* Verify we do not have a compound head page. */
573 if (WARN_ON(compound_head(&pages[i]) != &pages[i]))
574 return addr;
575
576 __SetPageSlab(&pages[i]);
577 }
578
579 /*
580 * Protect the first 2 pages. The first page is mostly unnecessary, and
581 * merely serves as an extended guard page. However, adding one
582 * additional page in the beginning gives us an even number of pages,
583 * which simplifies the mapping of address to metadata index.
584 */
585 for (i = 0; i < 2; i++) {
586 if (unlikely(!kfence_protect(addr)))
587 return addr;
588
589 addr += PAGE_SIZE;
590 }
591
592 for (i = 0; i < CONFIG_KFENCE_NUM_OBJECTS; i++) {
> 593 struct slab *slab = virt_to_slab(addr);
594 struct kfence_metadata *meta = &kfence_metadata[i];
595
596 /* Initialize metadata. */
597 slab->memcg_data = (unsigned long)&meta->objcg | MEMCG_DATA_OBJCGS;
598 INIT_LIST_HEAD(&meta->list);
599 raw_spin_lock_init(&meta->lock);
600 meta->state = KFENCE_OBJECT_UNUSED;
601 meta->addr = addr; /* Initialize for validation in metadata_to_pageaddr(). */
602 list_add_tail(&meta->list, &kfence_freelist);
603
604 /* Protect the right redzone. */
605 if (unlikely(!kfence_protect(addr + PAGE_SIZE)))
606 return addr;
607
608 addr += 2 * PAGE_SIZE;
609 }
610
611 /*
612 * The pool is live and will never be deallocated from this point on.
613 * Remove the pool object from the kmemleak object tree, as it would
614 * otherwise overlap with allocations returned by kfence_alloc(), which
615 * are registered with kmemleak through the slab post-alloc hook.
616 */
617 kmemleak_free(__kfence_pool);
618
619 return 0;
620 }
621

--
0-DAY CI Kernel Test Service
https://01.org/lkp

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