Re: [PATCH] mm: fix race between kmem_cache destroy, create and deactivate

From: kbuild test robot <lkp@intel.com>
To: Shakeel Butt <shakeelb@google.com>
Cc: kbuild-all@01.org, Michal Hocko <mhocko@kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Greg Thelen <gthelen@google.com>,
	Christoph Lameter <cl@linux.com>,
	Pekka Enberg <penberg@kernel.org>,
	David Rientjes <rientjes@google.com>,
	Joonsoo Kim <iamjoonsoo.kim@lge.com>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Vladimir Davydov <vdavydov.dev@gmail.com>,
	Tejun Heo <tj@kernel.org>, Linux MM <linux-mm@kvack.org>,
	cgroups@vger.kernel.org, LKML <linux-kernel@vger.kernel.org>,
	Shakeel Butt <shakeelb@google.com>
Subject: Re: [PATCH] mm: fix race between kmem_cache destroy, create and deactivate
Date: Wed, 23 May 2018 06:07:39 +0800	[thread overview]
Message-ID: <201805230631.w8mAKXOz%fengguang.wu@intel.com> (raw)
In-Reply-To: <20180521174116.171846-1-shakeelb@google.com>

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Hi Shakeel,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on mmotm/master]
[also build test ERROR on v4.17-rc6 next-20180517]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/Shakeel-Butt/mm-fix-race-between-kmem_cache-destroy-create-and-deactivate/20180523-041715
base:   git://git.cmpxchg.org/linux-mmotm.git master
config: i386-randconfig-a0-201820 (attached as .config)
compiler: gcc-4.9 (Debian 4.9.4-2) 4.9.4
reproduce:
        # save the attached .config to linux build tree
        make ARCH=i386 

All errors (new ones prefixed by >>):

   mm/slub.c: In function '__kmem_cache_alias':
>> mm/slub.c:4251:4: error: implicit declaration of function 'kmem_cache_put_locked' [-Werror=implicit-function-declaration]
       kmem_cache_put_locked(s);
       ^
   cc1: some warnings being treated as errors

vim +/kmem_cache_put_locked +4251 mm/slub.c

  4226	
  4227	struct kmem_cache *
  4228	__kmem_cache_alias(const char *name, unsigned int size, unsigned int align,
  4229			   slab_flags_t flags, void (*ctor)(void *))
  4230	{
  4231		struct kmem_cache *s, *c;
  4232	
  4233		s = find_mergeable(size, align, flags, name, ctor);
  4234		if (s && kmem_cache_tryget(s)) {
  4235			s->alias_count++;
  4236	
  4237			/*
  4238			 * Adjust the object sizes so that we clear
  4239			 * the complete object on kzalloc.
  4240			 */
  4241			s->object_size = max(s->object_size, size);
  4242			s->inuse = max(s->inuse, ALIGN(size, sizeof(void *)));
  4243	
  4244			for_each_memcg_cache(c, s) {
  4245				c->object_size = s->object_size;
  4246				c->inuse = max(c->inuse, ALIGN(size, sizeof(void *)));
  4247			}
  4248	
  4249			if (sysfs_slab_alias(s, name)) {
  4250				s->alias_count--;
> 4251				kmem_cache_put_locked(s);
  4252				s = NULL;
  4253			}
  4254		}
  4255	
  4256		return s;
  4257	}
  4258	

---
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