Re: [linux-next:master 8008/8345] mm/shrinker.c:100:1-7: preceding lock on line 83 (fwd)

[Qi Zheng <zhengqi.arch@bytedance.com>]

Hi Julia,

On 2023/9/29 22:33, Julia Lawall wrote:
> Should shrinker_mutex be released on the error path?

Yes, and this has been fixed by 
https://lore.kernel.org/lkml/20230928141517.12164-1-zhengqi.arch@bytedance.com/.

Thanks,
Qi
	

> 
> julia
> 
> ---------- Forwarded message ----------
> Date: Fri, 29 Sep 2023 21:31:25 +0800
> From: kernel test robot <lkp@intel.com>
> To: oe-kbuild@lists.linux.dev
> Cc: lkp@intel.com, Julia Lawall <julia.lawall@inria.fr>
> Subject: [linux-next:master 8008/8345] mm/shrinker.c:100:1-7: preceding lock on
>      line 83
> 
> BCC: lkp@intel.com
> CC: oe-kbuild-all@lists.linux.dev
> CC: Linux Memory Management List <linux-mm@kvack.org>
> TO: Qi Zheng <zhengqi.arch@bytedance.com>
> CC: Andrew Morton <akpm@linux-foundation.org>
> CC: Linux Memory Management List <linux-mm@kvack.org>
> CC: Muchun Song <songmuchun@bytedance.com>
> 
> Hi Qi,
> 
> FYI, the error/warning was bisected to this commit, please ignore it if it's irrelevant.
> 
> tree:   https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master
> head:   df964ce9ef9fea10cf131bf6bad8658fde7956f6
> commit: 3b0ec351e30dfbe71675deb22da8a9fe1894c87f [8008/8345] mm: shrinker: convert shrinker_rwsem to mutex
> :::::: branch date: 9 hours ago
> :::::: commit date: 3 days ago
> config: x86_64-randconfig-103-20230927 (https://download.01.org/0day-ci/archive/20230929/202309292114.VMjkyBBq-lkp@intel.com/config)
> compiler: gcc-12 (Debian 12.2.0-14) 12.2.0
> reproduce: (https://download.01.org/0day-ci/archive/20230929/202309292114.VMjkyBBq-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@intel.com>
> | Reported-by: Julia Lawall <julia.lawall@inria.fr>
> | Closes: https://lore.kernel.org/r/202309292114.VMjkyBBq-lkp@intel.com/
> 
> cocci warnings: (new ones prefixed by >>)
>>> mm/shrinker.c:100:1-7: preceding lock on line 83
> 
> vim +100 mm/shrinker.c
> 
> 2babd0d6e9cfca Qi Zheng 2023-09-11   76
> 2babd0d6e9cfca Qi Zheng 2023-09-11   77  int alloc_shrinker_info(struct mem_cgroup *memcg)
> 2babd0d6e9cfca Qi Zheng 2023-09-11   78  {
> 2babd0d6e9cfca Qi Zheng 2023-09-11   79  	struct shrinker_info *info;
> b6884b5f15cf5a Qi Zheng 2023-09-11   80  	int nid, ret = 0;
> b6884b5f15cf5a Qi Zheng 2023-09-11   81  	int array_size = 0;
> 2babd0d6e9cfca Qi Zheng 2023-09-11   82
> 3b0ec351e30dfb Qi Zheng 2023-09-11  @83  	mutex_lock(&shrinker_mutex);
> b6884b5f15cf5a Qi Zheng 2023-09-11   84  	array_size = shrinker_unit_size(shrinker_nr_max);
> 2babd0d6e9cfca Qi Zheng 2023-09-11   85  	for_each_node(nid) {
> b6884b5f15cf5a Qi Zheng 2023-09-11   86  		info = kvzalloc_node(sizeof(*info) + array_size, GFP_KERNEL, nid);
> b6884b5f15cf5a Qi Zheng 2023-09-11   87  		if (!info)
> b6884b5f15cf5a Qi Zheng 2023-09-11   88  			goto err;
> 2babd0d6e9cfca Qi Zheng 2023-09-11   89  		info->map_nr_max = shrinker_nr_max;
> b6884b5f15cf5a Qi Zheng 2023-09-11   90  		if (shrinker_unit_alloc(info, NULL, nid))
> b6884b5f15cf5a Qi Zheng 2023-09-11   91  			goto err;
> 2babd0d6e9cfca Qi Zheng 2023-09-11   92  		rcu_assign_pointer(memcg->nodeinfo[nid]->shrinker_info, info);
> 2babd0d6e9cfca Qi Zheng 2023-09-11   93  	}
> 3b0ec351e30dfb Qi Zheng 2023-09-11   94  	mutex_unlock(&shrinker_mutex);
> 2babd0d6e9cfca Qi Zheng 2023-09-11   95
> 2babd0d6e9cfca Qi Zheng 2023-09-11   96  	return ret;
> b6884b5f15cf5a Qi Zheng 2023-09-11   97
> b6884b5f15cf5a Qi Zheng 2023-09-11   98  err:
> b6884b5f15cf5a Qi Zheng 2023-09-11   99  	free_shrinker_info(memcg);
> b6884b5f15cf5a Qi Zheng 2023-09-11 @100  	return -ENOMEM;
> 2babd0d6e9cfca Qi Zheng 2023-09-11  101  }
> 2babd0d6e9cfca Qi Zheng 2023-09-11  102
> 
> :::::: The code at line 100 was first introduced by commit
> :::::: b6884b5f15cf5acf6886ec0704d799035477ad7e mm: shrinker: add a secondary array for shrinker_info::{map, nr_deferred}
> 
> :::::: TO: Qi Zheng <zhengqi.arch@bytedance.com>
> :::::: CC: Andrew Morton <akpm@linux-foundation.org>
>