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Subjectkernel/sched/isolation.c:143 housekeeping_setup() warn: always true condition '(first_cpu >= 0) => (0-u32max >= 0)'
tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head: 98369dccd2f8e16bf4c6621053af7aa4821dcf8e
commit: 257bf89d84121280904800acd25cc2c444c717ae sched/isolation: Fix boot crash when maxcpus < first housekeeping CPU
date: 2 days ago
config: xtensa-randconfig-r081-20240429 (https://download.01.org/0day-ci/archive/20240430/202404300915.WNvfwBz3-lkp@intel.com/config)
compiler: xtensa-linux-gcc (GCC) 13.2.0

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>
| Closes: https://lore.kernel.org/oe-kbuild-all/202404300915.WNvfwBz3-lkp@intel.com/

New smatch warnings:
kernel/sched/isolation.c:143 housekeeping_setup() warn: always true condition '(first_cpu >= 0) => (0-u32max >= 0)'

Old smatch warnings:
arch/xtensa/include/asm/thread_info.h:97 current_thread_info() warn: inconsistent indenting

vim +143 kernel/sched/isolation.c

117
118 static int __init housekeeping_setup(char *str, unsigned long flags)
119 {
120 cpumask_var_t non_housekeeping_mask, housekeeping_staging;
121 unsigned int first_cpu;
122 int err = 0;
123
124 if ((flags & HK_FLAG_TICK) && !(housekeeping.flags & HK_FLAG_TICK)) {
125 if (!IS_ENABLED(CONFIG_NO_HZ_FULL)) {
126 pr_warn("Housekeeping: nohz unsupported."
127 " Build with CONFIG_NO_HZ_FULL\n");
128 return 0;
129 }
130 }
131
132 alloc_bootmem_cpumask_var(&non_housekeeping_mask);
133 if (cpulist_parse(str, non_housekeeping_mask) < 0) {
134 pr_warn("Housekeeping: nohz_full= or isolcpus= incorrect CPU range\n");
135 goto free_non_housekeeping_mask;
136 }
137
138 alloc_bootmem_cpumask_var(&housekeeping_staging);
139 cpumask_andnot(housekeeping_staging,
140 cpu_possible_mask, non_housekeeping_mask);
141
142 first_cpu = cpumask_first_and(cpu_present_mask, housekeeping_staging);
> 143 if (first_cpu >= nr_cpu_ids || first_cpu >= setup_max_cpus) {
144 __cpumask_set_cpu(smp_processor_id(), housekeeping_staging);
145 __cpumask_clear_cpu(smp_processor_id(), non_housekeeping_mask);
146 if (!housekeeping.flags) {
147 pr_warn("Housekeeping: must include one present CPU, "
148 "using boot CPU:%d\n", smp_processor_id());
149 }
150 }
151
152 if (cpumask_empty(non_housekeeping_mask))
153 goto free_housekeeping_staging;
154
155 if (!housekeeping.flags) {
156 /* First setup call ("nohz_full=" or "isolcpus=") */
157 enum hk_type type;
158
159 for_each_set_bit(type, &flags, HK_TYPE_MAX)
160 housekeeping_setup_type(type, housekeeping_staging);
161 } else {
162 /* Second setup call ("nohz_full=" after "isolcpus=" or the reverse) */
163 enum hk_type type;
164 unsigned long iter_flags = flags & housekeeping.flags;
165
166 for_each_set_bit(type, &iter_flags, HK_TYPE_MAX) {
167 if (!cpumask_equal(housekeeping_staging,
168 housekeeping.cpumasks[type])) {
169 pr_warn("Housekeeping: nohz_full= must match isolcpus=\n");
170 goto free_housekeeping_staging;
171 }
172 }
173
174 iter_flags = flags & ~housekeeping.flags;
175
176 for_each_set_bit(type, &iter_flags, HK_TYPE_MAX)
177 housekeeping_setup_type(type, housekeeping_staging);
178 }
179
180 if ((flags & HK_FLAG_TICK) && !(housekeeping.flags & HK_FLAG_TICK))
181 tick_nohz_full_setup(non_housekeeping_mask);
182
183 housekeeping.flags |= flags;
184 err = 1;
185
186 free_housekeeping_staging:
187 free_bootmem_cpumask_var(housekeeping_staging);
188 free_non_housekeeping_mask:
189 free_bootmem_cpumask_var(non_housekeeping_mask);
190
191 return err;
192 }
193

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

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