Users can obtain ksm_profit of a cgroup just by:

/ # cat /sys/fs/cgroup/memory.ksm_stat
ksm_rmap_items 76800
ksm_zero_pages 0
ksm_merging_pages 76800
ksm_profit 309657600

Current implementation supports cgroup v1 temporarily; cgroup v2
compatibility is planned for future versions.

Signed-off-by: xu xin <xu.xin16@zte.com.cn>
---
 mm/memcontrol-v1.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/mm/memcontrol-v1.c b/mm/memcontrol-v1.c
index 7ee38d633d85..2cf2823c5514 100644
--- a/mm/memcontrol-v1.c
+++ b/mm/memcontrol-v1.c
@@ -1827,6 +1827,7 @@ struct memcg_ksm_stat {
 	unsigned long ksm_rmap_items;
 	long ksm_zero_pages;
 	unsigned long ksm_merging_pages;
+	long ksm_profit;
 };
 
 static int evaluate_memcg_ksm_stat(struct task_struct *task, void *arg)
@@ -1839,6 +1840,7 @@ static int evaluate_memcg_ksm_stat(struct task_struct *task, void *arg)
 		ksm_stat->ksm_rmap_items += mm->ksm_rmap_items;
 		ksm_stat->ksm_zero_pages += mm_ksm_zero_pages(mm);
 		ksm_stat->ksm_merging_pages += mm->ksm_merging_pages;
+		ksm_stat->ksm_profit += ksm_process_profit(mm);
 		mmput(mm);
 	}
 
@@ -1854,6 +1856,7 @@ static int memcg_ksm_stat_show(struct seq_file *m, void *v)
 	ksm_stat.ksm_rmap_items = 0;
 	ksm_stat.ksm_zero_pages = 0;
 	ksm_stat.ksm_merging_pages = 0;
+	ksm_stat.ksm_profit = 0;
 
 	/* summing all processes'ksm statistic items of this cgroup hierarchy */
 	mem_cgroup_scan_tasks(memcg, evaluate_memcg_ksm_stat, &ksm_stat);
@@ -1861,6 +1864,7 @@ static int memcg_ksm_stat_show(struct seq_file *m, void *v)
 	seq_printf(m, "ksm_rmap_items %lu\n", ksm_stat.ksm_rmap_items);
 	seq_printf(m, "ksm_zero_pages %ld\n", ksm_stat.ksm_zero_pages);
 	seq_printf(m, "ksm_merging_pages %ld\n", ksm_stat.ksm_merging_pages);
+	seq_printf(m, "ksm_profit %ld\n", ksm_stat.ksm_profit);
 
 	return 0;
 }
-- 
2.39.3

Hi xu,

kernel test robot noticed the following build errors:

[auto build test ERROR on akpm-mm/mm-everything]
[also build test ERROR on linus/master v6.15-rc3 next-20250422]
[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/xu-xin/memcontrol-rename-mem_cgroup_scan_tasks/20250422-231623
base:   https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-everything
patch link:    https://lore.kernel.org/r/20250422112251.3231599-1-xu.xin16%40zte.com.cn
patch subject: [PATCH RESEND 6/6] memcontrol-v1: add ksm_profit in cgroup/memory.ksm_stat
config: i386-buildonly-randconfig-006-20250423 (https://download.01.org/0day-ci/archive/20250423/202504231523.owjrO2Yy-lkp@intel.com/config)
compiler: clang version 20.1.2 (https://github.com/llvm/llvm-project 58df0ef89dd64126512e4ee27b4ac3fd8ddf6247)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250423/202504231523.owjrO2Yy-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/202504231523.owjrO2Yy-lkp@intel.com/

All errors (new ones prefixed by >>):

>> ld.lld: error: undefined symbol: ksm_process_profit
   >>> referenced by memcontrol-v1.c:1843 (mm/memcontrol-v1.c:1843)
   >>>               mm/memcontrol-v1.o:(evaluate_memcg_ksm_stat) in archive vmlinux.a

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