[PATCH linux-next]mm, oom:dump_tasks add rss detailed information printing

[yang.yang29]

From: Yong Wang <wang.yong12@xxxxxxxxxx>

When the system is under oom, it prints out the RSS information of
each process. However, we don't know the size of rss_anon, rss_file,
and rss_shmem.

To distinguish the memory occupied by anonymous or file mappings
or shmem, could help us identify the root cause of the oom.

So this patch adds RSS details, which refers to the /proc/<pid>/status[1].
It can help us know more about process memory usage.

Example of oom including the new rss_* fields:
[ 1630.902466] Tasks state (memory values in pages):
[ 1630.902870] [  pid  ]   uid  tgid total_vm      rss rss_anon rss_file rss_shmem pgtables_bytes swapents oom_score_adj name
[ 1630.903619] [    149]     0   149      486      288        0      288         0    36864        0             0 ash
[ 1630.904210] [    156]     0   156   153531   153345   153345        0         0  1269760        0             0 mm_test

[1] commit 8cee852ec53f ("mm, procfs: breakdown RSS for anon, shmem and file in /proc/pid/status").

Signed-off-by: Yong Wang <wang.yong12@xxxxxxxxxx>
Reviewed-by: Yang Yang <yang.yang29@xxxxxxxxxx>
---
 mm/oom_kill.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index 9e6071fde34a..91ccd82097c2 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -399,10 +399,11 @@ static int dump_task(struct task_struct *p, void *arg)
 		return 0;
 	}

-	pr_info("[%7d] %5d %5d %8lu %8lu %8ld %8lu         %5hd %s\n",
+	pr_info("[%7d] %5d %5d %8lu %8lu %8lu %8lu %9lu %8ld %8lu         %5hd %s\n",
 		task->pid, from_kuid(&init_user_ns, task_uid(task)),
 		task->tgid, task->mm->total_vm, get_mm_rss(task->mm),
-		mm_pgtables_bytes(task->mm),
+		get_mm_counter(task->mm, MM_ANONPAGES), get_mm_counter(task->mm, MM_FILEPAGES),
+		get_mm_counter(task->mm, MM_SHMEMPAGES), mm_pgtables_bytes(task->mm),
 		get_mm_counter(task->mm, MM_SWAPENTS),
 		task->signal->oom_score_adj, task->comm);
 	task_unlock(task);
@@ -423,7 +424,7 @@ static int dump_task(struct task_struct *p, void *arg)
 static void dump_tasks(struct oom_control *oc)
 {
 	pr_info("Tasks state (memory values in pages):\n");
-	pr_info("[  pid  ]   uid  tgid total_vm      rss pgtables_bytes swapents oom_score_adj name\n");
+	pr_info("[  pid  ]   uid  tgid total_vm      rss rss_anon rss_file rss_shmem pgtables_bytes swapents oom_score_adj name\n");

 	if (is_memcg_oom(oc))
 		mem_cgroup_scan_tasks(oc->memcg, dump_task, oc);
-- 
2.15.2