Re: [PATCH 2/3] hugetlb: Remove a few calls to page_folio()

[Dan Carpenter <dan.carpenter@linaro.org>]

Hi Matthew,

kernel test robot noticed the following build warnings:

https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Matthew-Wilcox-Oracle/hugetlb-Remove-a-few-calls-to-page_folio/20230823-002932
base:   https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-everything
patch link:    https://lore.kernel.org/r/20230822162808.4131399-2-willy%40infradead.org
patch subject: [PATCH 2/3] hugetlb: Remove a few calls to page_folio()
config: x86_64-randconfig-161-20230827 (https://download.01.org/0day-ci/archive/20231013/202310131039.ZgssYfIB-lkp@intel.com/config)
compiler: gcc-12 (Debian 12.2.0-14) 12.2.0
reproduce: (https://download.01.org/0day-ci/archive/20231013/202310131039.ZgssYfIB-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: Dan Carpenter <dan.carpenter@linaro.org>
| Closes: https://lore.kernel.org/r/202310131039.ZgssYfIB-lkp@intel.com/

smatch warnings:
mm/hugetlb.c:2246 remove_pool_huge_page() error: uninitialized symbol 'folio'.

vim +/folio +2246 mm/hugetlb.c

10c6ec49802b17 Mike Kravetz            2021-05-04  2224  static struct page *remove_pool_huge_page(struct hstate *h,
10c6ec49802b17 Mike Kravetz            2021-05-04  2225  						nodemask_t *nodes_allowed,
6ae11b278bca1c Lee Schermerhorn        2009-12-14  2226  						 bool acct_surplus)
e8c5c8249878fb Lee Schermerhorn        2009-09-21  2227  {
b2261026825ed3 Joonsoo Kim             2013-09-11  2228  	int nr_nodes, node;
cfd5082b514765 Sidhartha Kumar         2022-11-29  2229  	struct folio *folio;
e8c5c8249878fb Lee Schermerhorn        2009-09-21  2230  
9487ca60fd7fa2 Mike Kravetz            2021-05-04  2231  	lockdep_assert_held(&hugetlb_lock);
b2261026825ed3 Joonsoo Kim             2013-09-11  2232  	for_each_node_mask_to_free(h, nr_nodes, node, nodes_allowed) {
685f345708096e Lee Schermerhorn        2009-09-21  2233  		/*
685f345708096e Lee Schermerhorn        2009-09-21  2234  		 * If we're returning unused surplus pages, only examine
685f345708096e Lee Schermerhorn        2009-09-21  2235  		 * nodes with surplus pages.
685f345708096e Lee Schermerhorn        2009-09-21  2236  		 */
b2261026825ed3 Joonsoo Kim             2013-09-11  2237  		if ((!acct_surplus || h->surplus_huge_pages_node[node]) &&
b2261026825ed3 Joonsoo Kim             2013-09-11  2238  		    !list_empty(&h->hugepage_freelists[node])) {
e601ce76a2aabd Matthew Wilcox (Oracle  2023-08-22  2239) 			folio = list_entry(h->hugepage_freelists[node].next,
e601ce76a2aabd Matthew Wilcox (Oracle  2023-08-22  2240) 					  struct folio, lru);
cfd5082b514765 Sidhartha Kumar         2022-11-29  2241  			remove_hugetlb_folio(h, folio, acct_surplus);
9a76db09970938 Lee Schermerhorn        2009-12-14  2242  			break;

So we're always guaranteed to hit this break statement?

e8c5c8249878fb Lee Schermerhorn        2009-09-21  2243  		}
b2261026825ed3 Joonsoo Kim             2013-09-11  2244  	}
e8c5c8249878fb Lee Schermerhorn        2009-09-21  2245  
e601ce76a2aabd Matthew Wilcox (Oracle  2023-08-22 @2246) 	return &folio->page;
e8c5c8249878fb Lee Schermerhorn        2009-09-21  2247  }

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