[openeuler:OLK-5.10 1213/30000] mm/memcontrol.c:7050 uncharge_page() error: uninitialized symbol 'objcg'.

[kernel test robot <lkp@intel.com>]

BCC: lkp@intel.com
CC: oe-kbuild-all@lists.linux.dev
TO: kernel@openeuler.org
TO: Zheng Zengkai <zhengzengkai@huawei.com>

tree:   https://gitee.com/openeuler/kernel.git OLK-5.10
head:   950c74b8b6db893114b092f9fd2548037daa73f7
commit: 63472377281639f1cce1e1328288a69f9ed8beba [1213/30000] mm: memcontrol: use obj_cgroup APIs to charge kmem pages
:::::: branch date: 28 hours ago
:::::: commit date: 3 years ago
config: x86_64-randconfig-161-20241022 (https://download.01.org/0day-ci/archive/20241022/202410221923.9WVki2nh-lkp@intel.com/config)
compiler: gcc-12 (Debian 12.2.0-14) 12.2.0

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: Dan Carpenter <error27@gmail.com>
| Closes: https://lore.kernel.org/r/202410221923.9WVki2nh-lkp@intel.com/

smatch warnings:
mm/memcontrol.c:7050 uncharge_page() error: uninitialized symbol 'objcg'.

vim +/objcg +7050 mm/memcontrol.c

747db954cab64c Johannes Weiner         2014-08-08  7003  
a9d5adeeb4b2c7 Jérôme Glisse           2017-09-08  7004  static void uncharge_page(struct page *page, struct uncharge_gather *ug)
747db954cab64c Johannes Weiner         2014-08-08  7005  {
9f762dbe19b9f1 Johannes Weiner         2020-06-03  7006  	unsigned long nr_pages;
63472377281639 Muchun Song             2021-10-30  7007  	struct mem_cgroup *memcg;
63472377281639 Muchun Song             2021-10-30  7008  	struct obj_cgroup *objcg;
9f762dbe19b9f1 Johannes Weiner         2020-06-03  7009  
747db954cab64c Johannes Weiner         2014-08-08  7010  	VM_BUG_ON_PAGE(PageLRU(page), page);
747db954cab64c Johannes Weiner         2014-08-08  7011  
747db954cab64c Johannes Weiner         2014-08-08  7012  	/*
747db954cab64c Johannes Weiner         2014-08-08  7013  	 * Nobody should be changing or seriously looking at
63472377281639 Muchun Song             2021-10-30  7014  	 * page memcg or objcg at this point, we have fully
2983331575bfb2 Johannes Weiner         2014-12-10  7015  	 * exclusive access to the page.
747db954cab64c Johannes Weiner         2014-08-08  7016  	 */
63472377281639 Muchun Song             2021-10-30  7017  	if (PageMemcgKmem(page)) {
63472377281639 Muchun Song             2021-10-30  7018  		objcg = __page_objcg(page);
63472377281639 Muchun Song             2021-10-30  7019  		/*
63472377281639 Muchun Song             2021-10-30  7020  		 * This get matches the put at the end of the function and
63472377281639 Muchun Song             2021-10-30  7021  		 * kmem pages do not hold memcg references anymore.
63472377281639 Muchun Song             2021-10-30  7022  		 */
63472377281639 Muchun Song             2021-10-30  7023  		memcg = get_mem_cgroup_from_objcg(objcg);
63472377281639 Muchun Song             2021-10-30  7024  	} else {
63472377281639 Muchun Song             2021-10-30  7025  		memcg = __page_memcg(page);
63472377281639 Muchun Song             2021-10-30  7026  	}
63472377281639 Muchun Song             2021-10-30  7027  
63472377281639 Muchun Song             2021-10-30  7028  	if (!memcg)
63472377281639 Muchun Song             2021-10-30  7029  		return;
747db954cab64c Johannes Weiner         2014-08-08  7030  
63472377281639 Muchun Song             2021-10-30  7031  	if (ug->memcg != memcg) {
a9d5adeeb4b2c7 Jérôme Glisse           2017-09-08  7032  		if (ug->memcg) {
a9d5adeeb4b2c7 Jérôme Glisse           2017-09-08  7033  			uncharge_batch(ug);
a9d5adeeb4b2c7 Jérôme Glisse           2017-09-08  7034  			uncharge_gather_clear(ug);
747db954cab64c Johannes Weiner         2014-08-08  7035  		}
63472377281639 Muchun Song             2021-10-30  7036  		ug->memcg = memcg;
66a3bf90a949b5 Muchun Song             2021-10-30  7037  		ug->dummy_page = page;
f1796544a0ca0f Michal Hocko            2020-09-04  7038  
f1796544a0ca0f Michal Hocko            2020-09-04  7039  		/* pairs with css_put in uncharge_batch */
63472377281639 Muchun Song             2021-10-30  7040  		css_get(&memcg->css);
747db954cab64c Johannes Weiner         2014-08-08  7041  	}
747db954cab64c Johannes Weiner         2014-08-08  7042  
d8c6546b1aea84 Matthew Wilcox (Oracle  2019-09-23  7043) 	nr_pages = compound_nr(page);
9f762dbe19b9f1 Johannes Weiner         2020-06-03  7044  
63472377281639 Muchun Song             2021-10-30  7045  	if (PageMemcgKmem(page)) {
63472377281639 Muchun Song             2021-10-30  7046  		ug->nr_memory += nr_pages;
9f762dbe19b9f1 Johannes Weiner         2020-06-03  7047  		ug->nr_kmem += nr_pages;
63472377281639 Muchun Song             2021-10-30  7048  
63472377281639 Muchun Song             2021-10-30  7049  		page->memcg_data = 0;
63472377281639 Muchun Song             2021-10-30 @7050  		obj_cgroup_put(objcg);
63472377281639 Muchun Song             2021-10-30  7051  	} else {
63472377281639 Muchun Song             2021-10-30  7052  		/* LRU pages aren't accounted at the root level */
63472377281639 Muchun Song             2021-10-30  7053  		if (!mem_cgroup_is_root(memcg))
63472377281639 Muchun Song             2021-10-30  7054  			ug->nr_memory += nr_pages;
492cf0b0c21dc6 Roman Gushchin          2021-10-30  7055  		ug->pgpgout++;
747db954cab64c Johannes Weiner         2014-08-08  7056  
d1b942b7ac549e Roman Gushchin          2021-10-30  7057  		page->memcg_data = 0;
63472377281639 Muchun Song             2021-10-30  7058  	}
63472377281639 Muchun Song             2021-10-30  7059  
63472377281639 Muchun Song             2021-10-30  7060  	css_put(&memcg->css);
a9d5adeeb4b2c7 Jérôme Glisse           2017-09-08  7061  }
a9d5adeeb4b2c7 Jérôme Glisse           2017-09-08  7062  

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