mm, oom: describe task memory unit, larger PID pad

The default page memory unit of OOM task dump events might not be
intuitive and potentially misleading for the non-initiated when debugging
OOM events: These are pages and not kBs.  Add a small printk prior to the
task dump informing that the memory units are actually memory _pages_.

Also extends PID field to align on up to 7 characters.
Reference https://lkml.org/lkml/2018/7/3/1201

Link: http://lkml.kernel.org/r/c795eb5129149ed8a6345c273aba167ff1bbd388.1530715938.git.rfreire@redhat.com
Signed-off-by: Rodrigo Freire <rfreire@redhat.com>
Acked-by: David Rientjes <rientjes@google.com>
Acked-by: Rafael Aquini <aquini@redhat.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index 66a86dd..ed5e6a2 100644 (file)
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -400,7 +400,8 @@ static void dump_tasks(struct mem_cgroup *memcg, const nodemask_t *nodemask)
        struct task_struct *p;
        struct task_struct *task;
 
-       pr_info("[ pid ]   uid  tgid total_vm      rss pgtables_bytes swapents oom_score_adj name\n");
+       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");
        rcu_read_lock();
        for_each_process(p) {
                if (oom_unkillable_task(p, memcg, nodemask))
@@ -416,7 +417,7 @@ static void dump_tasks(struct mem_cgroup *memcg, const nodemask_t *nodemask)
                        continue;
                }
 
-               pr_info("[%5d] %5d %5d %8lu %8lu %8ld %8lu         %5hd %s\n",
+               pr_info("[%7d] %5d %5d %8lu %8lu %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),