Hi Jan, kernel test robot noticed the following build warnings: [auto build test WARNING on linus/master] [also build test WARNING on v6.6-rc6 next-20231018] [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/Jan-Kara/lib-find-Make-functions-safe-on-changing-bitmaps/20231011-230553 base: linus/master patch link: https://lore.kernel.org/r/20231011150252.32737-1-jack%40suse.cz patch subject: [PATCH 1/2] lib/find: Make functions safe on changing bitmaps config: i386-randconfig-002-20231018 (https://download.01.org/0day-ci/archive/20231019/202310190005.NqJcRXtK-lkp@xxxxxxxxx/config) compiler: gcc-12 (Debian 12.2.0-14) 12.2.0 reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20231019/202310190005.NqJcRXtK-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/202310190005.NqJcRXtK-lkp@xxxxxxxxx/ All warnings (new ones prefixed by >>): mm/percpu.c: In function 'pcpu_build_alloc_info': >> mm/percpu.c:2885:26: warning: array subscript 32 is above array bounds of 'int[32]' [-Warray-bounds] 2885 | group_map[cpu] = group; | ~~~~~~~~~^~~~~ mm/percpu.c:2842:20: note: while referencing 'group_map' 2842 | static int group_map[NR_CPUS] __initdata; | ^~~~~~~~~ vim +2885 mm/percpu.c 3c9a024fde58b0 Tejun Heo 2010-09-09 2813 3c9a024fde58b0 Tejun Heo 2010-09-09 2814 /* pcpu_build_alloc_info() is used by both embed and page first chunk */ 3c9a024fde58b0 Tejun Heo 2010-09-09 2815 #if defined(BUILD_EMBED_FIRST_CHUNK) || defined(BUILD_PAGE_FIRST_CHUNK) 3c9a024fde58b0 Tejun Heo 2010-09-09 2816 /** 3c9a024fde58b0 Tejun Heo 2010-09-09 2817 * pcpu_build_alloc_info - build alloc_info considering distances between CPUs 3c9a024fde58b0 Tejun Heo 2010-09-09 2818 * @reserved_size: the size of reserved percpu area in bytes 3c9a024fde58b0 Tejun Heo 2010-09-09 2819 * @dyn_size: minimum free size for dynamic allocation in bytes 3c9a024fde58b0 Tejun Heo 2010-09-09 2820 * @atom_size: allocation atom size 3c9a024fde58b0 Tejun Heo 2010-09-09 2821 * @cpu_distance_fn: callback to determine distance between cpus, optional 3c9a024fde58b0 Tejun Heo 2010-09-09 2822 * 3c9a024fde58b0 Tejun Heo 2010-09-09 2823 * This function determines grouping of units, their mappings to cpus 3c9a024fde58b0 Tejun Heo 2010-09-09 2824 * and other parameters considering needed percpu size, allocation 3c9a024fde58b0 Tejun Heo 2010-09-09 2825 * atom size and distances between CPUs. 3c9a024fde58b0 Tejun Heo 2010-09-09 2826 * bffc4375897ea0 Yannick Guerrini 2015-03-06 2827 * Groups are always multiples of atom size and CPUs which are of 3c9a024fde58b0 Tejun Heo 2010-09-09 2828 * LOCAL_DISTANCE both ways are grouped together and share space for 3c9a024fde58b0 Tejun Heo 2010-09-09 2829 * units in the same group. The returned configuration is guaranteed 3c9a024fde58b0 Tejun Heo 2010-09-09 2830 * to have CPUs on different nodes on different groups and >=75% usage 3c9a024fde58b0 Tejun Heo 2010-09-09 2831 * of allocated virtual address space. 3c9a024fde58b0 Tejun Heo 2010-09-09 2832 * 3c9a024fde58b0 Tejun Heo 2010-09-09 2833 * RETURNS: 3c9a024fde58b0 Tejun Heo 2010-09-09 2834 * On success, pointer to the new allocation_info is returned. On 3c9a024fde58b0 Tejun Heo 2010-09-09 2835 * failure, ERR_PTR value is returned. 3c9a024fde58b0 Tejun Heo 2010-09-09 2836 */ 258e0815e2b170 Dennis Zhou 2021-02-14 2837 static struct pcpu_alloc_info * __init __flatten pcpu_build_alloc_info( 3c9a024fde58b0 Tejun Heo 2010-09-09 2838 size_t reserved_size, size_t dyn_size, 3c9a024fde58b0 Tejun Heo 2010-09-09 2839 size_t atom_size, 3c9a024fde58b0 Tejun Heo 2010-09-09 2840 pcpu_fc_cpu_distance_fn_t cpu_distance_fn) 3c9a024fde58b0 Tejun Heo 2010-09-09 2841 { 3c9a024fde58b0 Tejun Heo 2010-09-09 2842 static int group_map[NR_CPUS] __initdata; 3c9a024fde58b0 Tejun Heo 2010-09-09 2843 static int group_cnt[NR_CPUS] __initdata; d7d29ac76f7efb Wonhyuk Yang 2020-10-30 2844 static struct cpumask mask __initdata; 3c9a024fde58b0 Tejun Heo 2010-09-09 2845 const size_t static_size = __per_cpu_end - __per_cpu_start; 3c9a024fde58b0 Tejun Heo 2010-09-09 2846 int nr_groups = 1, nr_units = 0; 3c9a024fde58b0 Tejun Heo 2010-09-09 2847 size_t size_sum, min_unit_size, alloc_size; 3f649ab728cda8 Kees Cook 2020-06-03 2848 int upa, max_upa, best_upa; /* units_per_alloc */ 3c9a024fde58b0 Tejun Heo 2010-09-09 2849 int last_allocs, group, unit; 3c9a024fde58b0 Tejun Heo 2010-09-09 2850 unsigned int cpu, tcpu; 3c9a024fde58b0 Tejun Heo 2010-09-09 2851 struct pcpu_alloc_info *ai; 3c9a024fde58b0 Tejun Heo 2010-09-09 2852 unsigned int *cpu_map; 3c9a024fde58b0 Tejun Heo 2010-09-09 2853 3c9a024fde58b0 Tejun Heo 2010-09-09 2854 /* this function may be called multiple times */ 3c9a024fde58b0 Tejun Heo 2010-09-09 2855 memset(group_map, 0, sizeof(group_map)); 3c9a024fde58b0 Tejun Heo 2010-09-09 2856 memset(group_cnt, 0, sizeof(group_cnt)); d7d29ac76f7efb Wonhyuk Yang 2020-10-30 2857 cpumask_clear(&mask); 3c9a024fde58b0 Tejun Heo 2010-09-09 2858 3c9a024fde58b0 Tejun Heo 2010-09-09 2859 /* calculate size_sum and ensure dyn_size is enough for early alloc */ 3c9a024fde58b0 Tejun Heo 2010-09-09 2860 size_sum = PFN_ALIGN(static_size + reserved_size + 3c9a024fde58b0 Tejun Heo 2010-09-09 2861 max_t(size_t, dyn_size, PERCPU_DYNAMIC_EARLY_SIZE)); 3c9a024fde58b0 Tejun Heo 2010-09-09 2862 dyn_size = size_sum - static_size - reserved_size; 3c9a024fde58b0 Tejun Heo 2010-09-09 2863 3c9a024fde58b0 Tejun Heo 2010-09-09 2864 /* 3c9a024fde58b0 Tejun Heo 2010-09-09 2865 * Determine min_unit_size, alloc_size and max_upa such that 3c9a024fde58b0 Tejun Heo 2010-09-09 2866 * alloc_size is multiple of atom_size and is the smallest 25985edcedea63 Lucas De Marchi 2011-03-30 2867 * which can accommodate 4k aligned segments which are equal to 3c9a024fde58b0 Tejun Heo 2010-09-09 2868 * or larger than min_unit_size. 3c9a024fde58b0 Tejun Heo 2010-09-09 2869 */ 3c9a024fde58b0 Tejun Heo 2010-09-09 2870 min_unit_size = max_t(size_t, size_sum, PCPU_MIN_UNIT_SIZE); 3c9a024fde58b0 Tejun Heo 2010-09-09 2871 9c01516278ef87 Dennis Zhou (Facebook 2017-07-15 2872) /* determine the maximum # of units that can fit in an allocation */ 3c9a024fde58b0 Tejun Heo 2010-09-09 2873 alloc_size = roundup(min_unit_size, atom_size); 3c9a024fde58b0 Tejun Heo 2010-09-09 2874 upa = alloc_size / min_unit_size; f09f1243ca2d5d Alexander Kuleshov 2015-11-05 2875 while (alloc_size % upa || (offset_in_page(alloc_size / upa))) 3c9a024fde58b0 Tejun Heo 2010-09-09 2876 upa--; 3c9a024fde58b0 Tejun Heo 2010-09-09 2877 max_upa = upa; 3c9a024fde58b0 Tejun Heo 2010-09-09 2878 d7d29ac76f7efb Wonhyuk Yang 2020-10-30 2879 cpumask_copy(&mask, cpu_possible_mask); d7d29ac76f7efb Wonhyuk Yang 2020-10-30 2880 3c9a024fde58b0 Tejun Heo 2010-09-09 2881 /* group cpus according to their proximity */ d7d29ac76f7efb Wonhyuk Yang 2020-10-30 2882 for (group = 0; !cpumask_empty(&mask); group++) { d7d29ac76f7efb Wonhyuk Yang 2020-10-30 2883 /* pop the group's first cpu */ d7d29ac76f7efb Wonhyuk Yang 2020-10-30 2884 cpu = cpumask_first(&mask); 3c9a024fde58b0 Tejun Heo 2010-09-09 @2885 group_map[cpu] = group; 3c9a024fde58b0 Tejun Heo 2010-09-09 2886 group_cnt[group]++; d7d29ac76f7efb Wonhyuk Yang 2020-10-30 2887 cpumask_clear_cpu(cpu, &mask); d7d29ac76f7efb Wonhyuk Yang 2020-10-30 2888 d7d29ac76f7efb Wonhyuk Yang 2020-10-30 2889 for_each_cpu(tcpu, &mask) { d7d29ac76f7efb Wonhyuk Yang 2020-10-30 2890 if (!cpu_distance_fn || d7d29ac76f7efb Wonhyuk Yang 2020-10-30 2891 (cpu_distance_fn(cpu, tcpu) == LOCAL_DISTANCE && d7d29ac76f7efb Wonhyuk Yang 2020-10-30 2892 cpu_distance_fn(tcpu, cpu) == LOCAL_DISTANCE)) { d7d29ac76f7efb Wonhyuk Yang 2020-10-30 2893 group_map[tcpu] = group; d7d29ac76f7efb Wonhyuk Yang 2020-10-30 2894 group_cnt[group]++; d7d29ac76f7efb Wonhyuk Yang 2020-10-30 2895 cpumask_clear_cpu(tcpu, &mask); d7d29ac76f7efb Wonhyuk Yang 2020-10-30 2896 } d7d29ac76f7efb Wonhyuk Yang 2020-10-30 2897 } 3c9a024fde58b0 Tejun Heo 2010-09-09 2898 } d7d29ac76f7efb Wonhyuk Yang 2020-10-30 2899 nr_groups = group; 3c9a024fde58b0 Tejun Heo 2010-09-09 2900 3c9a024fde58b0 Tejun Heo 2010-09-09 2901 /* 9c01516278ef87 Dennis Zhou (Facebook 2017-07-15 2902) * Wasted space is caused by a ratio imbalance of upa to group_cnt. 9c01516278ef87 Dennis Zhou (Facebook 2017-07-15 2903) * Expand the unit_size until we use >= 75% of the units allocated. 9c01516278ef87 Dennis Zhou (Facebook 2017-07-15 2904) * Related to atom_size, which could be much larger than the unit_size. 3c9a024fde58b0 Tejun Heo 2010-09-09 2905 */ 3c9a024fde58b0 Tejun Heo 2010-09-09 2906 last_allocs = INT_MAX; 4829c791b22f98 Dennis Zhou 2021-06-14 2907 best_upa = 0; 3c9a024fde58b0 Tejun Heo 2010-09-09 2908 for (upa = max_upa; upa; upa--) { 3c9a024fde58b0 Tejun Heo 2010-09-09 2909 int allocs = 0, wasted = 0; 3c9a024fde58b0 Tejun Heo 2010-09-09 2910 f09f1243ca2d5d Alexander Kuleshov 2015-11-05 2911 if (alloc_size % upa || (offset_in_page(alloc_size / upa))) 3c9a024fde58b0 Tejun Heo 2010-09-09 2912 continue; 3c9a024fde58b0 Tejun Heo 2010-09-09 2913 3c9a024fde58b0 Tejun Heo 2010-09-09 2914 for (group = 0; group < nr_groups; group++) { 3c9a024fde58b0 Tejun Heo 2010-09-09 2915 int this_allocs = DIV_ROUND_UP(group_cnt[group], upa); 3c9a024fde58b0 Tejun Heo 2010-09-09 2916 allocs += this_allocs; 3c9a024fde58b0 Tejun Heo 2010-09-09 2917 wasted += this_allocs * upa - group_cnt[group]; 3c9a024fde58b0 Tejun Heo 2010-09-09 2918 } 3c9a024fde58b0 Tejun Heo 2010-09-09 2919 3c9a024fde58b0 Tejun Heo 2010-09-09 2920 /* 3c9a024fde58b0 Tejun Heo 2010-09-09 2921 * Don't accept if wastage is over 1/3. The 3c9a024fde58b0 Tejun Heo 2010-09-09 2922 * greater-than comparison ensures upa==1 always 3c9a024fde58b0 Tejun Heo 2010-09-09 2923 * passes the following check. 3c9a024fde58b0 Tejun Heo 2010-09-09 2924 */ 3c9a024fde58b0 Tejun Heo 2010-09-09 2925 if (wasted > num_possible_cpus() / 3) 3c9a024fde58b0 Tejun Heo 2010-09-09 2926 continue; 3c9a024fde58b0 Tejun Heo 2010-09-09 2927 3c9a024fde58b0 Tejun Heo 2010-09-09 2928 /* and then don't consume more memory */ 3c9a024fde58b0 Tejun Heo 2010-09-09 2929 if (allocs > last_allocs) 3c9a024fde58b0 Tejun Heo 2010-09-09 2930 break; 3c9a024fde58b0 Tejun Heo 2010-09-09 2931 last_allocs = allocs; 3c9a024fde58b0 Tejun Heo 2010-09-09 2932 best_upa = upa; 3c9a024fde58b0 Tejun Heo 2010-09-09 2933 } 4829c791b22f98 Dennis Zhou 2021-06-14 2934 BUG_ON(!best_upa); 3c9a024fde58b0 Tejun Heo 2010-09-09 2935 upa = best_upa; 3c9a024fde58b0 Tejun Heo 2010-09-09 2936 3c9a024fde58b0 Tejun Heo 2010-09-09 2937 /* allocate and fill alloc_info */ 3c9a024fde58b0 Tejun Heo 2010-09-09 2938 for (group = 0; group < nr_groups; group++) 3c9a024fde58b0 Tejun Heo 2010-09-09 2939 nr_units += roundup(group_cnt[group], upa); 3c9a024fde58b0 Tejun Heo 2010-09-09 2940 3c9a024fde58b0 Tejun Heo 2010-09-09 2941 ai = pcpu_alloc_alloc_info(nr_groups, nr_units); 3c9a024fde58b0 Tejun Heo 2010-09-09 2942 if (!ai) 3c9a024fde58b0 Tejun Heo 2010-09-09 2943 return ERR_PTR(-ENOMEM); 3c9a024fde58b0 Tejun Heo 2010-09-09 2944 cpu_map = ai->groups[0].cpu_map; 3c9a024fde58b0 Tejun Heo 2010-09-09 2945 3c9a024fde58b0 Tejun Heo 2010-09-09 2946 for (group = 0; group < nr_groups; group++) { 3c9a024fde58b0 Tejun Heo 2010-09-09 2947 ai->groups[group].cpu_map = cpu_map; 3c9a024fde58b0 Tejun Heo 2010-09-09 2948 cpu_map += roundup(group_cnt[group], upa); 3c9a024fde58b0 Tejun Heo 2010-09-09 2949 } 3c9a024fde58b0 Tejun Heo 2010-09-09 2950 3c9a024fde58b0 Tejun Heo 2010-09-09 2951 ai->static_size = static_size; 3c9a024fde58b0 Tejun Heo 2010-09-09 2952 ai->reserved_size = reserved_size; 3c9a024fde58b0 Tejun Heo 2010-09-09 2953 ai->dyn_size = dyn_size; 3c9a024fde58b0 Tejun Heo 2010-09-09 2954 ai->unit_size = alloc_size / upa; 3c9a024fde58b0 Tejun Heo 2010-09-09 2955 ai->atom_size = atom_size; 3c9a024fde58b0 Tejun Heo 2010-09-09 2956 ai->alloc_size = alloc_size; 3c9a024fde58b0 Tejun Heo 2010-09-09 2957 2de7852fe9096e Peng Fan 2019-02-20 2958 for (group = 0, unit = 0; group < nr_groups; group++) { 3c9a024fde58b0 Tejun Heo 2010-09-09 2959 struct pcpu_group_info *gi = &ai->groups[group]; 3c9a024fde58b0 Tejun Heo 2010-09-09 2960 3c9a024fde58b0 Tejun Heo 2010-09-09 2961 /* 3c9a024fde58b0 Tejun Heo 2010-09-09 2962 * Initialize base_offset as if all groups are located 3c9a024fde58b0 Tejun Heo 2010-09-09 2963 * back-to-back. The caller should update this to 3c9a024fde58b0 Tejun Heo 2010-09-09 2964 * reflect actual allocation. 3c9a024fde58b0 Tejun Heo 2010-09-09 2965 */ 3c9a024fde58b0 Tejun Heo 2010-09-09 2966 gi->base_offset = unit * ai->unit_size; 3c9a024fde58b0 Tejun Heo 2010-09-09 2967 3c9a024fde58b0 Tejun Heo 2010-09-09 2968 for_each_possible_cpu(cpu) 3c9a024fde58b0 Tejun Heo 2010-09-09 2969 if (group_map[cpu] == group) 3c9a024fde58b0 Tejun Heo 2010-09-09 2970 gi->cpu_map[gi->nr_units++] = cpu; 3c9a024fde58b0 Tejun Heo 2010-09-09 2971 gi->nr_units = roundup(gi->nr_units, upa); 3c9a024fde58b0 Tejun Heo 2010-09-09 2972 unit += gi->nr_units; 3c9a024fde58b0 Tejun Heo 2010-09-09 2973 } 3c9a024fde58b0 Tejun Heo 2010-09-09 2974 BUG_ON(unit != nr_units); 3c9a024fde58b0 Tejun Heo 2010-09-09 2975 3c9a024fde58b0 Tejun Heo 2010-09-09 2976 return ai; 3c9a024fde58b0 Tejun Heo 2010-09-09 2977 } 23f917169ef157 Kefeng Wang 2022-01-19 2978 -- 0-DAY CI Kernel Test Service https://github.com/intel/lkp-tests/wiki
