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

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

[Joel Savitz]

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), UID 0,
total-vm:133880028kB, anon-rss:129754836kB, file-rss:0kB,
shmem-rss:0kB

Signed-off-by: Joel Savitz <jsavitz@redhat.com>
---
 mm/oom_kill.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index 3a2484884cfd..22972648b758 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -874,9 +874,9 @@ 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), UID %d, total-vm:%lukB, anon-rss:%lukB, file-rss:%lukB, shmem-rss:%lukB\n",
 		message, task_pid_nr(victim), victim->comm,
-		K(victim->mm->total_vm),
+		task_uid(victim).val, 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)));
-- 
2.18.1

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

[Rafael Aquini]

On Wed, Apr 24, 2019 at 02:20:13PM -0400, Joel Savitz wrote:
> 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), UID 0,
> total-vm:133880028kB, anon-rss:129754836kB, file-rss:0kB,
> shmem-rss:0kB
> 
> Signed-off-by: Joel Savitz <jsavitz@redhat.com>
> ---
>  mm/oom_kill.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/mm/oom_kill.c b/mm/oom_kill.c
> index 3a2484884cfd..22972648b758 100644
> --- a/mm/oom_kill.c
> +++ b/mm/oom_kill.c
> @@ -874,9 +874,9 @@ 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), UID %d, total-vm:%lukB, anon-rss:%lukB, file-rss:%lukB, shmem-rss:%lukB\n",
>  		message, task_pid_nr(victim), victim->comm,
> -		K(victim->mm->total_vm),
> +		task_uid(victim).val, 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)));
> -- 
> 2.18.1
> 
Acked-by: Rafael Aquini <aquini@redhat.com>

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

[David Rientjes]

On Wed, 24 Apr 2019, Joel Savitz wrote:

> 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), UID 0,
> total-vm:133880028kB, anon-rss:129754836kB, file-rss:0kB,
> shmem-rss:0kB
> 
> Signed-off-by: Joel Savitz <jsavitz@redhat.com>

Makes sense, could you add it to the end of the message in case anybody is 
parsing the current string and we would now break their regex?

This would also need from_kuid(&init_user_ns, task_uid(task)) instead.

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

[Michal Hocko]

On Wed 24-04-19 14:20:13, Joel Savitz wrote:
> 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.

There was a more general rework of this message
http://lkml.kernel.org/r/1542799799-36184-1-git-send-email-ufo19890607@gmail.com
but I do not see it merged into Andrew's tree. Could you have a look and
pursue it, please?

-- 
Michal Hocko
SUSE Labs