linux-kernel - Re: [PATCH 1/4] mm/swap, memcg: Introduce infrastructure for cgroup-based swap priority

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Message-ID: <202507171936.fGW4muEc-lkp@intel.com>
Date: Thu, 17 Jul 2025 19:20:58 +0800
From: kernel test robot <lkp@...el.com>
To: Youngjun Park <youngjun.park@....com>, akpm@...ux-foundation.org,
	hannes@...xchg.org
Cc: oe-kbuild-all@...ts.linux.dev, mhocko@...nel.org,
	roman.gushchin@...ux.dev, shakeel.butt@...ux.dev,
	muchun.song@...ux.dev, shikemeng@...weicloud.com,
	kasong@...cent.com, nphamcs@...il.com, bhe@...hat.com,
	baohua@...nel.org, chrisl@...nel.org, cgroups@...r.kernel.org,
	linux-mm@...ck.org, linux-kernel@...r.kernel.org, gunho.lee@....com,
	iamjoonsoo.kim@....com, taejoon.song@....com,
	Youngjun Park <youngjun.park@....com>,
	Michal Koutný <mkoutny@...e.com>
Subject: Re: [PATCH 1/4] mm/swap, memcg: Introduce infrastructure for
 cgroup-based swap priority

Hi Youngjun,

kernel test robot noticed the following build warnings:

[auto build test WARNING on 347e9f5043c89695b01e66b3ed111755afcf1911]

url:    https://github.com/intel-lab-lkp/linux/commits/Youngjun-Park/mm-swap-memcg-Introduce-infrastructure-for-cgroup-based-swap-priority/20250717-042648
base:   347e9f5043c89695b01e66b3ed111755afcf1911
patch link:    https://lore.kernel.org/r/20250716202006.3640584-2-youngjun.park%40lge.com
patch subject: [PATCH 1/4] mm/swap, memcg: Introduce infrastructure for cgroup-based swap priority
config: loongarch-allyesconfig (https://download.01.org/0day-ci/archive/20250717/202507171936.fGW4muEc-lkp@intel.com/config)
compiler: clang version 21.0.0git (https://github.com/llvm/llvm-project 16534d19bf50bde879a83f0ae62875e2c5120e64)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250717/202507171936.fGW4muEc-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/202507171936.fGW4muEc-lkp@intel.com/

All warnings (new ones prefixed by >>):

>> mm/memcontrol.c:5462:12: warning: variable 'id' is uninitialized when used here [-Wuninitialized]
    5462 |                                 memcg, id, SWAP_PRIORITY_GLOBAL);
         |                                        ^~
   mm/memcontrol.c:5414:8: note: initialize the variable 'id' to silence this warning
    5414 |         u64 id;
         |               ^
         |                = 0
   1 warning generated.


vim +/id +5462 mm/memcontrol.c

  5408	
  5409	#ifdef CONFIG_SWAP_CGROUP_PRIORITY
  5410	static ssize_t swap_cgroup_priority_write(struct kernfs_open_file *of,
  5411						  char *buf, size_t nbytes, loff_t off)
  5412	{
  5413		struct mem_cgroup *memcg = mem_cgroup_from_css(of_css(of));
  5414		u64 id;
  5415		int prio;
  5416		int ret;
  5417		char first_token[32];
  5418		char second_token[32];
  5419		char dummy[2];
  5420		char *stripped_buf;
  5421		int num_parsed;
  5422	
  5423		stripped_buf = strstrip(buf);
  5424		num_parsed = sscanf(stripped_buf, "%31s %31s %1s", first_token,
  5425				    second_token, dummy);
  5426		if (num_parsed == 2) {
  5427			if (strcmp(first_token, "default") == 0) {
  5428				if (strcmp(second_token, "none") == 0)
  5429					ret = apply_swap_cgroup_priority(
  5430						memcg, DEFAULT_ID, SWAP_PRIORITY_GLOBAL);
  5431				else if (strcmp(second_token, "disabled") == 0)
  5432					ret = apply_swap_cgroup_priority(
  5433						memcg, DEFAULT_ID, SWAP_PRIORITY_DISABLE);
  5434				else
  5435					ret = -EINVAL;
  5436			} else {
  5437				ret = kstrtoull(first_token, 10, &id);
  5438				if (ret)
  5439					return -EINVAL;
  5440	
  5441				if (strcmp(second_token, "none") == 0) {
  5442					ret = apply_swap_cgroup_priority(
  5443						memcg, id, SWAP_PRIORITY_GLOBAL);
  5444				} else if (strcmp(second_token, "disabled") == 0) {
  5445					ret = apply_swap_cgroup_priority(
  5446						memcg, id, SWAP_PRIORITY_DISABLE);
  5447				} else {
  5448					ret = kstrtoint(second_token, 10, &prio);
  5449					if (ret)
  5450						return -EINVAL;
  5451					if (prio == -1)
  5452						return -EINVAL;
  5453					else if (prio > SHRT_MAX || prio < SHRT_MIN)
  5454						return -EINVAL;
  5455					ret = apply_swap_cgroup_priority(memcg, id,
  5456									 prio);
  5457				}
  5458			}
  5459		} else if (num_parsed == 1) {
  5460			if (strcmp(first_token, "none") == 0)
  5461				ret = apply_swap_cgroup_priority(
> 5462					memcg, id, SWAP_PRIORITY_GLOBAL);
  5463			else if (strcmp(first_token, "disabled") == 0)
  5464				ret = apply_swap_cgroup_priority(
  5465					memcg, id, SWAP_PRIORITY_DISABLE);
  5466			else
  5467				ret = -EINVAL;
  5468		} else {
  5469			return -EINVAL;
  5470		}
  5471	
  5472		if (ret)
  5473			return ret;
  5474	
  5475		return nbytes;
  5476	}
  5477	

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki