Re: [PATCH] cgroup/rstat: change cgroup_base_stat to atomic

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

Hi Bertrand,

kernel test robot noticed the following build errors:

[auto build test ERROR on tj-cgroup/for-next]
[also build test ERROR on linus/master v6.16-rc2 next-20250617]
[cannot apply to trace/for-next]
[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/Bertrand-Wlodarczyk/cgroup-rstat-change-cgroup_base_stat-to-atomic/20250617-183242
base:   https://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup.git for-next
patch link:    https://lore.kernel.org/r/20250617102644.752201-2-bertrand.wlodarczyk%40intel.com
patch subject: [PATCH] cgroup/rstat: change cgroup_base_stat to atomic
config: arc-randconfig-001-20250617 (https://download.01.org/0day-ci/archive/20250617/202506172158.OEJ5qjT6-lkp@intel.com/config)
compiler: arc-linux-gcc (GCC) 11.5.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250617/202506172158.OEJ5qjT6-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>
| Closes: https://lore.kernel.org/oe-kbuild-all/202506172158.OEJ5qjT6-lkp@intel.com/

All errors (new ones prefixed by >>):

   kernel/cgroup/rstat.c: In function 'css_rstat_init':
   kernel/cgroup/rstat.c:415:55: warning: variable 'rstatbc' set but not used [-Wunused-but-set-variable]
     415 |                         struct cgroup_rstat_base_cpu *rstatbc;
         |                                                       ^~~~~~~
   kernel/cgroup/rstat.c: In function 'root_cgroup_cputime':
>> kernel/cgroup/rstat.c:629:42: error: passing argument 2 of 'atomic64_add' from incompatible pointer type [-Werror=incompatible-pointer-types]
     629 |                 atomic64_add(sys + user, &cputime->sum_exec_runtime);
         |                                          ^~~~~~~~~~~~~~~~~~~~~~~~~~
         |                                          |
         |                                          atomic_long_t * {aka atomic_t *}
   In file included from include/linux/atomic.h:82,
                    from include/asm-generic/bitops/lock.h:5,
                    from arch/arc/include/asm/bitops.h:188,
                    from include/linux/bitops.h:67,
                    from include/linux/thread_info.h:27,
                    from include/linux/sched.h:14,
                    from include/linux/cgroup.h:12,
                    from kernel/cgroup/cgroup-internal.h:5,
                    from kernel/cgroup/rstat.c:2:
   include/linux/atomic/atomic-instrumented.h:1680:33: note: expected 'atomic64_t *' but argument is of type 'atomic_long_t *' {aka 'atomic_t *'}
    1680 | atomic64_add(s64 i, atomic64_t *v)
         |                     ~~~~~~~~~~~~^
   In file included from ./arch/arc/include/generated/asm/div64.h:1,
                    from include/linux/math.h:6,
                    from include/linux/kernel.h:27,
                    from include/linux/cpumask.h:11,
                    from include/linux/smp.h:13,
                    from include/linux/lockdep.h:14,
                    from include/linux/spinlock.h:63,
                    from include/linux/sched.h:2209,
                    from include/linux/cgroup.h:12,
                    from kernel/cgroup/cgroup-internal.h:5,
                    from kernel/cgroup/rstat.c:2:
   kernel/cgroup/rstat.c: In function 'cgroup_base_stat_cputime_show':
   include/asm-generic/div64.h:183:35: warning: comparison of distinct pointer types lacks a cast
     183 |         (void)(((typeof((n)) *)0) == ((uint64_t *)0));  \
         |                                   ^~
   kernel/cgroup/rstat.c:677:9: note: in expansion of macro 'do_div'
     677 |         do_div(utime, NSEC_PER_USEC);
         |         ^~~~~~
   include/asm-generic/div64.h:183:35: warning: comparison of distinct pointer types lacks a cast
     183 |         (void)(((typeof((n)) *)0) == ((uint64_t *)0));  \
         |                                   ^~
   kernel/cgroup/rstat.c:681:9: note: in expansion of macro 'do_div'
     681 |         do_div(stime, NSEC_PER_USEC);
         |         ^~~~~~
   include/asm-generic/div64.h:183:35: warning: comparison of distinct pointer types lacks a cast
     183 |         (void)(((typeof((n)) *)0) == ((uint64_t *)0));  \
         |                                   ^~
   kernel/cgroup/rstat.c:685:9: note: in expansion of macro 'do_div'
     685 |         do_div(ntime, NSEC_PER_USEC);
         |         ^~~~~~
   cc1: some warnings being treated as errors


vim +/atomic64_add +629 kernel/cgroup/rstat.c

   599	
   600	/*
   601	 * compute the cputime for the root cgroup by getting the per cpu data
   602	 * at a global level, then categorizing the fields in a manner consistent
   603	 * with how it is done by __cgroup_account_cputime_field for each bit of
   604	 * cpu time attributed to a cgroup.
   605	 */
   606	static void root_cgroup_cputime(struct cgroup_base_stat *bstat)
   607	{
   608		struct atomic_task_cputime *cputime = &bstat->cputime;
   609		int i;
   610	
   611		memset(bstat, 0, sizeof(*bstat));
   612		for_each_possible_cpu(i) {
   613			struct kernel_cpustat kcpustat;
   614			u64 *cpustat = kcpustat.cpustat;
   615			u64 user = 0;
   616			u64 sys = 0;
   617	
   618			kcpustat_cpu_fetch(&kcpustat, i);
   619	
   620			user += cpustat[CPUTIME_USER];
   621			user += cpustat[CPUTIME_NICE];
   622			atomic64_add(user, &cputime->utime);
   623	
   624			sys += cpustat[CPUTIME_SYSTEM];
   625			sys += cpustat[CPUTIME_IRQ];
   626			sys += cpustat[CPUTIME_SOFTIRQ];
   627			atomic64_add(sys, &cputime->stime);
   628	
 > 629			atomic64_add(sys + user, &cputime->sum_exec_runtime);
   630	

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