Re: [PATCH 2/4] memcg: reduce memory for the lruvec and memcg stats

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

Hi Shakeel,

kernel test robot noticed the following build errors:

[auto build test ERROR on next-20240422]
[cannot apply to akpm-mm/mm-everything linus/master v6.9-rc5 v6.9-rc4 v6.9-rc3 v6.9-rc5]
[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/Shakeel-Butt/mm-rearrange-node_stat_item-to-put-memcg-stats-at-start/20240423-132451
base:   next-20240422
patch link:    https://lore.kernel.org/r/20240423051826.791934-3-shakeel.butt%40linux.dev
patch subject: [PATCH 2/4] memcg: reduce memory for the lruvec and memcg stats
config: x86_64-buildonly-randconfig-002-20240423 (https://download.01.org/0day-ci/archive/20240423/202404232230.94gQwAI2-lkp@intel.com/config)
compiler: clang version 17.0.6 (https://github.com/llvm/llvm-project 6009708b4367171ccdbf4b5905cb6a803753fe18)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240423/202404232230.94gQwAI2-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/202404232230.94gQwAI2-lkp@intel.com/

All errors (new ones prefixed by >>):

>> mm/memcontrol.c:1651:2: error: call to '__compiletime_assert_963' declared with 'error' attribute: BUILD_BUG_ON failed: ARRAY_SIZE(memory_stats) != MEMCG_NR_STAT - 1
    1651 |         BUILD_BUG_ON(ARRAY_SIZE(memory_stats) != MEMCG_NR_STAT - 1);
         |         ^
   include/linux/build_bug.h:50:2: note: expanded from macro 'BUILD_BUG_ON'
      50 |         BUILD_BUG_ON_MSG(condition, "BUILD_BUG_ON failed: " #condition)
         |         ^
   include/linux/build_bug.h:39:37: note: expanded from macro 'BUILD_BUG_ON_MSG'
      39 | #define BUILD_BUG_ON_MSG(cond, msg) compiletime_assert(!(cond), msg)
         |                                     ^
   include/linux/compiler_types.h:460:2: note: expanded from macro 'compiletime_assert'
     460 |         _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__)
         |         ^
   include/linux/compiler_types.h:448:2: note: expanded from macro '_compiletime_assert'
     448 |         __compiletime_assert(condition, msg, prefix, suffix)
         |         ^
   include/linux/compiler_types.h:441:4: note: expanded from macro '__compiletime_assert'
     441 |                         prefix ## suffix();                             \
         |                         ^
   <scratch space>:40:1: note: expanded from here
      40 | __compiletime_assert_963
         | ^
   1 error generated.


vim +1651 mm/memcontrol.c

  1645	
  1646	static void memcg_stat_format(struct mem_cgroup *memcg, struct seq_buf *s)
  1647	{
  1648		int i;
  1649	
  1650		/* Reduce by 1 for MEMCG_SWAP as that is not exposed in v2. */
> 1651		BUILD_BUG_ON(ARRAY_SIZE(memory_stats) != MEMCG_NR_STAT - 1);
  1652	
  1653		/*
  1654		 * Provide statistics on the state of the memory subsystem as
  1655		 * well as cumulative event counters that show past behavior.
  1656		 *
  1657		 * This list is ordered following a combination of these gradients:
  1658		 * 1) generic big picture -> specifics and details
  1659		 * 2) reflecting userspace activity -> reflecting kernel heuristics
  1660		 *
  1661		 * Current memory state:
  1662		 */
  1663		mem_cgroup_flush_stats(memcg);
  1664	
  1665		for (i = 0; i < ARRAY_SIZE(memory_stats); i++) {
  1666			u64 size;
  1667	
  1668			size = memcg_page_state_output(memcg, memory_stats[i].idx);
  1669			seq_buf_printf(s, "%s %llu\n", memory_stats[i].name, size);
  1670	
  1671			if (unlikely(memory_stats[i].idx == NR_SLAB_UNRECLAIMABLE_B)) {
  1672				size += memcg_page_state_output(memcg,
  1673								NR_SLAB_RECLAIMABLE_B);
  1674				seq_buf_printf(s, "slab %llu\n", size);
  1675			}
  1676		}
  1677	
  1678		/* Accumulated memory events */
  1679		seq_buf_printf(s, "pgscan %lu\n",
  1680			       memcg_events(memcg, PGSCAN_KSWAPD) +
  1681			       memcg_events(memcg, PGSCAN_DIRECT) +
  1682			       memcg_events(memcg, PGSCAN_KHUGEPAGED));
  1683		seq_buf_printf(s, "pgsteal %lu\n",
  1684			       memcg_events(memcg, PGSTEAL_KSWAPD) +
  1685			       memcg_events(memcg, PGSTEAL_DIRECT) +
  1686			       memcg_events(memcg, PGSTEAL_KHUGEPAGED));
  1687	
  1688		for (i = 0; i < ARRAY_SIZE(memcg_vm_event_stat); i++) {
  1689			if (memcg_vm_event_stat[i] == PGPGIN ||
  1690			    memcg_vm_event_stat[i] == PGPGOUT)
  1691				continue;
  1692	
  1693			seq_buf_printf(s, "%s %lu\n",
  1694				       vm_event_name(memcg_vm_event_stat[i]),
  1695				       memcg_events(memcg, memcg_vm_event_stat[i]));
  1696		}
  1697	
  1698		/* The above should easily fit into one page */
  1699		WARN_ON_ONCE(seq_buf_has_overflowed(s));
  1700	}
  1701	

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