Re: [PATCH v8] mm: slub: move sysfs slab alloc/free interfaces to debugfs

[Faiyaz Mohammed]

On 6/1/2021 5:44 PM, Vlastimil Babka wrote:
> On 6/1/21 1:08 PM, kernel test robot wrote:
>> Hi Faiyaz,
>>
>> Thank you for the patch! Yet something to improve:
>>
>> [auto build test ERROR on linus/master]
>> [also build test ERROR on v5.13-rc4]
>> [cannot apply to hnaz-linux-mm/master next-20210601]
>> [If your patch is applied to the wrong git tree, kindly drop us a note.
>> And when submitting patch, we suggest to use '--base' as documented in
>> https://git-scm.com/docs/git-format-patch]
>>
>> url:    https://github.com/0day-ci/linux/commits/Faiyaz-Mohammed/mm-slub-move-sysfs-slab-alloc-free-interfaces-to-debugfs/20210601-180903
>> base:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git c2131f7e73c9e9365613e323d65c7b9e5b910f56
>> config: i386-tinyconfig (attached as .config)
>> compiler: gcc-9 (Debian 9.3.0-22) 9.3.0
>> reproduce (this is a W=1 build):
>>         # https://github.com/0day-ci/linux/commit/9540acc4691d680b7124d8daa1a2eb98a97ee19a
>>         git remote add linux-review https://github.com/0day-ci/linux
>>         git fetch --no-tags linux-review Faiyaz-Mohammed/mm-slub-move-sysfs-slab-alloc-free-interfaces-to-debugfs/20210601-180903
>>         git checkout 9540acc4691d680b7124d8daa1a2eb98a97ee19a
>>         # save the attached .config to linux build tree
>>         make W=1 ARCH=i386 
>>
>> If you fix the issue, kindly add following tag as appropriate
>> Reported-by: kernel test robot <lkp@xxxxxxxxx>
>>
>> All errors (new ones prefixed by >>):
>>
>>    mm/slab_common.c: In function 'slab_caches_to_rcu_destroy_workfn':
>>>> mm/slab_common.c:452:3: error: implicit declaration of function 'debugfs_slab_release' [-Werror=implicit-function-declaration]
>>      452 |   debugfs_slab_release(s);
>>          |   ^~~~~~~~~~~~~~~~~~~~
>>    cc1: some warnings being treated as errors
> 
> Oh, right, CONFIG_SLOB.
> How about moving the ifdef-ed declaration from slub-def.h to mm/slab.h and
> discarding the slab-def.h empty one. That will take care of SLOB too.
> 

Yes, doing the same.
>> vim +/debugfs_slab_release +452 mm/slab_common.c
>>
>>    427	
>>    428	static void slab_caches_to_rcu_destroy_workfn(struct work_struct *work)
>>    429	{
>>    430		LIST_HEAD(to_destroy);
>>    431		struct kmem_cache *s, *s2;
>>    432	
>>    433		/*
>>    434		 * On destruction, SLAB_TYPESAFE_BY_RCU kmem_caches are put on the
>>    435		 * @slab_caches_to_rcu_destroy list.  The slab pages are freed
>>    436		 * through RCU and the associated kmem_cache are dereferenced
>>    437		 * while freeing the pages, so the kmem_caches should be freed only
>>    438		 * after the pending RCU operations are finished.  As rcu_barrier()
>>    439		 * is a pretty slow operation, we batch all pending destructions
>>    440		 * asynchronously.
>>    441		 */
>>    442		mutex_lock(&slab_mutex);
>>    443		list_splice_init(&slab_caches_to_rcu_destroy, &to_destroy);
>>    444		mutex_unlock(&slab_mutex);
>>    445	
>>    446		if (list_empty(&to_destroy))
>>    447			return;
>>    448	
>>    449		rcu_barrier();
>>    450	
>>    451		list_for_each_entry_safe(s, s2, &to_destroy, list) {
>>  > 452			debugfs_slab_release(s);
>>    453			kfence_shutdown_cache(s);
>>    454	#ifdef SLAB_SUPPORTS_SYSFS
>>    455			sysfs_slab_release(s);
>>    456	#else
>>    457			slab_kmem_cache_release(s);
>>    458	#endif
>>    459		}
>>    460	}
>>    461	
>>
>> ---
>> 0-DAY CI Kernel Test Service, Intel Corporation
>> https://lists.01.org/hyperkitty/list/kbuild-all@xxxxxxxxxxxx
>>
>