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    Subject[PATCH] mm/oom: Add oom_score_adj and pgtables to Killed process message
    Date
    For an OOM event: print oom_score_adj value for the OOM Killed process to
    document what the oom score adjust value was at the time the process was
    OOM Killed. The adjustment value can be set by user code and it affects
    the resulting oom_score so it is used to influence kill process selection.

    When eligible tasks are not printed (sysctl oom_dump_tasks = 0) printing
    this value is the only documentation of the value for the process being
    killed. Having this value on the Killed process message is useful to
    document if a miscconfiguration occurred or to confirm that the
    oom_score_adj configuration applies as expected.

    An example which illustates both misconfiguration and validation that
    the oom_score_adj was applied as expected is:

    Aug 14 23:00:02 testserver kernel: Out of memory: Killed process 2692
    (systemd-udevd) total-vm:1056800kB, anon-rss:1052760kB, file-rss:4kB,
    shmem-rss:0kB pgtables:22kB oom_score_adj:1000

    The systemd-udevd is a critical system application that should have
    an oom_score_adj of -1000. It was miconfigured to have a adjustment of
    1000 making it a highly favored OOM kill target process. The output
    documents both the misconfiguration and the fact that the process
    was correctly targeted by OOM due to the miconfiguration. This can
    be quite helpful for triage and problem determination.

    The addition of the pgtables_bytes shows page table usage by the
    process and is a useful measure of the memory size of the process.

    Signed-off-by: Edward Chron <echron@arista.com>
    Acked-by: Michal Hocko <mhocko@suse.com>
    Acked-by: David Rientjes <rientjes@google.com>
    ---
    mm/oom_kill.c | 12 ++++++------
    1 file changed, 6 insertions(+), 6 deletions(-)

    diff --git a/mm/oom_kill.c b/mm/oom_kill.c
    index eda2e2a0bdc6..98cb3943e5a2 100644
    --- a/mm/oom_kill.c
    +++ b/mm/oom_kill.c
    @@ -884,12 +884,12 @@ 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",
    - 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)));
    + pr_err("%s: Killed process %d (%s) total-vm:%lukB, anon-rss:%lukB, file-rss:%lukB, shmem-rss:%lukB pgtables:%lukB oom_score_adj:%hd\n",
    + message, task_pid_nr(victim), victim->comm, K(mm->total_vm),
    + K(get_mm_counter(mm, MM_ANONPAGES)),
    + K(get_mm_counter(mm, MM_FILEPAGES)),
    + K(get_mm_counter(mm, MM_SHMEMPAGES)),
    + mm_pgtables_bytes(mm), victim->signal->oom_score_adj);
    task_unlock(victim);

    /*
    --
    2.20.1
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