Re: [PATCH 8/8] mm/swap: reduce swap cache search space

From: kernel test robot
Date: Thu Apr 18 2024 - 14:22:07 EST

Hi Kairui,

kernel test robot noticed the following build errors:

[auto build test ERROR on ceph-client/testing]
[also build test ERROR on ceph-client/for-linus trondmy-nfs/linux-next konis-nilfs2/upstream jaegeuk-f2fs/dev-test jaegeuk-f2fs/dev cifs/for-next linus/master v6.9-rc4]
[cannot apply to akpm-mm/mm-everything next-20240418]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url: https://github.com/intel-lab-lkp/linux/commits/Kairui-Song/NFS-remove-nfs_page_lengthg-and-usage-of-page_index/20240418-001343
base: https://github.com/ceph/ceph-client.git testing
patch link: https://lore.kernel.org/r/20240417160842.76665-9-ryncsn%40gmail.com
patch subject: [PATCH 8/8] mm/swap: reduce swap cache search space
config: i386-buildonly-randconfig-002-20240419 (https://download.01.org/0day-ci/archive/20240419/202404190258.wljFnvCL-lkp@xxxxxxxxx/config)
compiler: gcc-9 (Ubuntu 9.5.0-4ubuntu2) 9.5.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240419/202404190258.wljFnvCL-lkp@xxxxxxxxx/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@xxxxxxxxx>
| Closes: https://lore.kernel.org/oe-kbuild-all/202404190258.wljFnvCL-lkp@xxxxxxxxx/

All errors (new ones prefixed by >>):

mm/huge_memory.c: In function '__split_huge_page':
>> mm/huge_memory.c:2906:12: error: implicit declaration of function 'swap_cache_index' [-Werror=implicit-function-declaration]
2906 | offset = swap_cache_index(folio->swap);
| ^~~~~~~~~~~~~~~~
cc1: some warnings being treated as errors


vim +/swap_cache_index +2906 mm/huge_memory.c

2888
2889 static void __split_huge_page(struct page *page, struct list_head *list,
2890 pgoff_t end, unsigned int new_order)
2891 {
2892 struct folio *folio = page_folio(page);
2893 struct page *head = &folio->page;
2894 struct lruvec *lruvec;
2895 struct address_space *swap_cache = NULL;
2896 unsigned long offset = 0;
2897 int i, nr_dropped = 0;
2898 unsigned int new_nr = 1 << new_order;
2899 int order = folio_order(folio);
2900 unsigned int nr = 1 << order;
2901
2902 /* complete memcg works before add pages to LRU */
2903 split_page_memcg(head, order, new_order);
2904
2905 if (folio_test_anon(folio) && folio_test_swapcache(folio)) {
> 2906 offset = swap_cache_index(folio->swap);
2907 swap_cache = swap_address_space(folio->swap);
2908 xa_lock(&swap_cache->i_pages);
2909 }
2910
2911 /* lock lru list/PageCompound, ref frozen by page_ref_freeze */
2912 lruvec = folio_lruvec_lock(folio);
2913
2914 ClearPageHasHWPoisoned(head);
2915
2916 for (i = nr - new_nr; i >= new_nr; i -= new_nr) {
2917 __split_huge_page_tail(folio, i, lruvec, list, new_order);
2918 /* Some pages can be beyond EOF: drop them from page cache */
2919 if (head[i].index >= end) {
2920 struct folio *tail = page_folio(head + i);
2921
2922 if (shmem_mapping(folio->mapping))
2923 nr_dropped++;
2924 else if (folio_test_clear_dirty(tail))
2925 folio_account_cleaned(tail,
2926 inode_to_wb(folio->mapping->host));
2927 __filemap_remove_folio(tail, NULL);
2928 folio_put(tail);
2929 } else if (!PageAnon(page)) {
2930 __xa_store(&folio->mapping->i_pages, head[i].index,
2931 head + i, 0);
2932 } else if (swap_cache) {
2933 __xa_store(&swap_cache->i_pages, offset + i,
2934 head + i, 0);
2935 }
2936 }
2937
2938 if (!new_order)
2939 ClearPageCompound(head);
2940 else {
2941 struct folio *new_folio = (struct folio *)head;
2942
2943 folio_set_order(new_folio, new_order);
2944 }
2945 unlock_page_lruvec(lruvec);
2946 /* Caller disabled irqs, so they are still disabled here */
2947
2948 split_page_owner(head, order, new_order);
2949
2950 /* See comment in __split_huge_page_tail() */
2951 if (folio_test_anon(folio)) {
2952 /* Additional pin to swap cache */
2953 if (folio_test_swapcache(folio)) {
2954 folio_ref_add(folio, 1 + new_nr);
2955 xa_unlock(&swap_cache->i_pages);
2956 } else {
2957 folio_ref_inc(folio);
2958 }
2959 } else {
2960 /* Additional pin to page cache */
2961 folio_ref_add(folio, 1 + new_nr);
2962 xa_unlock(&folio->mapping->i_pages);
2963 }
2964 local_irq_enable();
2965
2966 if (nr_dropped)
2967 shmem_uncharge(folio->mapping->host, nr_dropped);
2968 remap_page(folio, nr);
2969
2970 if (folio_test_swapcache(folio))
2971 split_swap_cluster(folio->swap);
2972
2973 /*
2974 * set page to its compound_head when split to non order-0 pages, so
2975 * we can skip unlocking it below, since PG_locked is transferred to
2976 * the compound_head of the page and the caller will unlock it.
2977 */
2978 if (new_order)
2979 page = compound_head(page);
2980
2981 for (i = 0; i < nr; i += new_nr) {
2982 struct page *subpage = head + i;
2983 struct folio *new_folio = page_folio(subpage);
2984 if (subpage == page)
2985 continue;
2986 folio_unlock(new_folio);
2987
2988 /*
2989 * Subpages may be freed if there wasn't any mapping
2990 * like if add_to_swap() is running on a lru page that
2991 * had its mapping zapped. And freeing these pages
2992 * requires taking the lru_lock so we do the put_page
2993 * of the tail pages after the split is complete.
2994 */
2995 free_page_and_swap_cache(subpage);
2996 }
2997 }
2998

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