Re: [PATCH] mm/oom_kill, proc: replace magic number 1000 with OOM_SCORE_ADJ_MAX

[Song Hu <husong@kylinos.cn>]

On 2026/8/11 11:36, Ye Liu wrote:
> --- a/mm/oom_kill.c
> +++ b/mm/oom_kill.c
> @@ -230,7 +230,7 @@ long oom_badness(struct task_struct *p, unsigned long totalpages)
>  	task_unlock(p);
>
>  	/* Normalize to oom_score_adj units */
> -	adj *= totalpages / 1000;
> +	adj *= totalpages / OOM_SCORE_ADJ_MAX;

One thing this line hides: for a memcg OOM, totalpages is
mem_cgroup_get_max(), which can be below 1000 pages when the
container limit is under 4M.  The division then yields 0, the whole
oom_score_adj contribution goes away, and a task protected with
-997 scores the same as a best-effort task with 1000.  The -1000
exemption is checked separately above and still works.

DIV_ROUND_UP(totalpages, OOM_SCORE_ADJ_MAX) would preserve the adj
weighting for small limits and change nothing meaningful for large
ones.  This is an edge case, so probably fine to leave as is -
noting it here since the line is being touched anyway.