Hi Minchan,

I love your patch! Yet something to improve:

[auto build test ERROR on linux/master]
[also build test ERROR on linus/master v5.12-rc2 next-20210309]
[cannot apply to hnaz-linux-mm/master]
[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]

url:    
https://github.com/0day-ci/linux/commits/Minchan-Kim/mm-disable-LRU-pagevec-during-the-migration-temporarily/20210309-131826
base:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 
144c79ef33536b4ecb4951e07dbc1f2b7fa99d32
config: openrisc-randconfig-r026-20210308 (attached as .config)
compiler: or1k-linux-gcc (GCC) 9.3.0
reproduce (this is a W=1 build):
        wget 
https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O 
~/bin/make.cross
        chmod +x ~/bin/make.cross
        # 
https://github.com/0day-ci/linux/commit/dfca8699b8fb8cf3bed2297e261fca53c0fc523c
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review 
Minchan-Kim/mm-disable-LRU-pagevec-during-the-migration-temporarily/20210309-131826
        git checkout dfca8699b8fb8cf3bed2297e261fca53c0fc523c
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross 
ARCH=openrisc 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <l...@intel.com>

All errors (new ones prefixed by >>):

   mm/swap.c:745:6: warning: no previous prototype for '__lru_add_drain_all' 
[-Wmissing-prototypes]
     745 | void __lru_add_drain_all(bool force_all_cpus)
         |      ^~~~~~~~~~~~~~~~~~~
   mm/swap.c: In function '__lru_add_drain_all':
>> mm/swap.c:827:7: error: implicit declaration of function 'has_bh_in_lru' 
>> [-Werror=implicit-function-declaration]
     827 |       has_bh_in_lru(cpu, NULL)) {
         |       ^~~~~~~~~~~~~
   cc1: some warnings being treated as errors


vim +/has_bh_in_lru +827 mm/swap.c

   744  
   745  void __lru_add_drain_all(bool force_all_cpus)
   746  {
   747          /*
   748           * lru_drain_gen - Global pages generation number
   749           *
   750           * (A) Definition: global lru_drain_gen = x implies that all 
generations
   751           *     0 < n <= x are already *scheduled* for draining.
   752           *
   753           * This is an optimization for the highly-contended use case 
where a
   754           * user space workload keeps constantly generating a flow of 
pages for
   755           * each CPU.
   756           */
   757          static unsigned int lru_drain_gen;
   758          static struct cpumask has_work;
   759          static DEFINE_MUTEX(lock);
   760          unsigned cpu, this_gen;
   761  
   762          /*
   763           * Make sure nobody triggers this path before mm_percpu_wq is 
fully
   764           * initialized.
   765           */
   766          if (WARN_ON(!mm_percpu_wq))
   767                  return;
   768  
   769          /*
   770           * Guarantee pagevec counter stores visible by this CPU are 
visible to
   771           * other CPUs before loading the current drain generation.
   772           */
   773          smp_mb();
   774  
   775          /*
   776           * (B) Locally cache global LRU draining generation number
   777           *
   778           * The read barrier ensures that the counter is loaded before 
the mutex
   779           * is taken. It pairs with smp_mb() inside the mutex critical 
section
   780           * at (D).
   781           */
   782          this_gen = smp_load_acquire(&lru_drain_gen);
   783  
   784          mutex_lock(&lock);
   785  
   786          /*
   787           * (C) Exit the draining operation if a newer generation, from 
another
   788           * lru_add_drain_all(), was already scheduled for draining. 
Check (A).
   789           */
   790          if (unlikely(this_gen != lru_drain_gen && !force_all_cpus))
   791                  goto done;
   792  
   793          /*
   794           * (D) Increment global generation number
   795           *
   796           * Pairs with smp_load_acquire() at (B), outside of the critical
   797           * section. Use a full memory barrier to guarantee that the new 
global
   798           * drain generation number is stored before loading pagevec 
counters.
   799           *
   800           * This pairing must be done here, before the 
for_each_online_cpu loop
   801           * below which drains the page vectors.
   802           *
   803           * Let x, y, and z represent some system CPU numbers, where x < 
y < z.
   804           * Assume CPU #z is is in the middle of the for_each_online_cpu 
loop
   805           * below and has already reached CPU #y's per-cpu data. CPU #x 
comes
   806           * along, adds some pages to its per-cpu vectors, then calls
   807           * lru_add_drain_all().
   808           *
   809           * If the paired barrier is done at any later step, e.g. after 
the
   810           * loop, CPU #x will just exit at (C) and miss flushing out all 
of its
   811           * added pages.
   812           */
   813          WRITE_ONCE(lru_drain_gen, lru_drain_gen + 1);
   814          smp_mb();
   815  
   816          cpumask_clear(&has_work);
   817          for_each_online_cpu(cpu) {
   818                  struct work_struct *work = &per_cpu(lru_add_drain_work, 
cpu);
   819  
   820                  if (force_all_cpus ||
   821                      pagevec_count(&per_cpu(lru_pvecs.lru_add, cpu)) ||
   822                      data_race(pagevec_count(&per_cpu(lru_rotate.pvec, 
cpu))) ||
   823                      
pagevec_count(&per_cpu(lru_pvecs.lru_deactivate_file, cpu)) ||
   824                      pagevec_count(&per_cpu(lru_pvecs.lru_deactivate, 
cpu)) ||
   825                      pagevec_count(&per_cpu(lru_pvecs.lru_lazyfree, 
cpu)) ||
   826                      need_activate_page_drain(cpu) ||
 > 827                      has_bh_in_lru(cpu, NULL)) {
   828                          INIT_WORK(work, lru_add_drain_per_cpu);
   829                          queue_work_on(cpu, mm_percpu_wq, work);
   830                          __cpumask_set_cpu(cpu, &has_work);
   831                  }
   832          }
   833  
   834          for_each_cpu(cpu, &has_work)
   835                  flush_work(&per_cpu(lru_add_drain_work, cpu));
   836  
   837  done:
   838          mutex_unlock(&lock);
   839  }
   840  

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-...@lists.01.org

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