[PATCH v2] mm/oom_killer: Add task UID to info message on an oom kill

[Joel Savitz <jsavitz@redhat.com>]

In the event of an oom kill, useful information about the killed
process is printed to dmesg. Users, especially system administrators,
will find it useful to immediately see the UID of the process.

In the following example, abuse_the_ram is the name of a program
that attempts to iteratively allocate all available memory until it is
stopped by force.

Current message:

Out of memory: Killed process 35389 (abuse_the_ram)
total-vm:133718232kB, anon-rss:129624980kB, file-rss:0kB,
shmem-rss:0kB

Patched message:

Out of memory: Killed process 2739 (abuse_the_ram),
total-vm:133880028kB, anon-rss:129754836kB, file-rss:0kB,
shmem-rss:0kB, UID 0

Signed-off-by: Joel Savitz <jsavitz@redhat.com>
---
 mm/oom_kill.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index 3a2484884cfd..af2e3faa72a0 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -874,12 +874,13 @@ static void __oom_kill_process(struct task_struct *victim, const char *message)
 	 */
 	do_send_sig_info(SIGKILL, SEND_SIG_PRIV, victim, PIDTYPE_TGID);
 	mark_oom_victim(victim);
-	pr_err("%s: Killed process %d (%s) total-vm:%lukB, anon-rss:%lukB, file-rss:%lukB, shmem-rss:%lukB\n",
+	pr_err("%s: Killed process %d (%s) total-vm:%lukB, anon-rss:%lukB, file-rss:%lukB, shmem-rss:%lukB, UID %d\n",
 		message, task_pid_nr(victim), victim->comm,
 		K(victim->mm->total_vm),
 		K(get_mm_counter(victim->mm, MM_ANONPAGES)),
 		K(get_mm_counter(victim->mm, MM_FILEPAGES)),
-		K(get_mm_counter(victim->mm, MM_SHMEMPAGES)));
+		K(get_mm_counter(victim->mm, MM_SHMEMPAGES)),
+		from_kuid(&init_user_ns, task_uid(victim)));
 	task_unlock(victim);
 
 	/*
-- 
2.18.1