memcg, oom: cleanup unused memcg_oom_gfp_mask and memcg_oom_order

Since commit 857f213 ("memcg, oom: remove unnecessary check in
mem_cgroup_oom_synchronize()"), memcg_oom_gfp_mask and memcg_oom_order are
no longer used any more.

Link: https://lkml.kernel.org/r/20240509032628.1217652-1-xiujianfeng@huawei.com
Signed-off-by: Xiu Jianfeng <xiujianfeng@huawei.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Shakeel Butt <shakeel.butt@linux.dev>
Reviewed-by: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Benjamin Segall <bsegall@google.com>
Cc: Daniel Bristot de Oliveira <bristot@redhat.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt (Google) <rostedt@goodmis.org>
Cc: Valentin Schneider <vschneid@redhat.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Author: Xiu Jianfeng

include/linux/sched.h

@@ -1448,8 +1448,6 @@ struct task_struct {
 
 #ifdef CONFIG_MEMCG
 	struct mem_cgroup		*memcg_in_oom;
-	gfp_t				memcg_oom_gfp_mask;
-	int				memcg_oom_order;
 
 	/* Number of pages to reclaim on returning to userland: */
 	unsigned int			memcg_nr_pages_over_high;

mm/memcontrol.c

@@ -2188,8 +2188,6 @@ static bool mem_cgroup_oom(struct mem_cgroup *memcg, gfp_t mask, int order)
 		if (current->in_user_fault) {
 			css_get(&memcg->css);
 			current->memcg_in_oom = memcg;
-			current->memcg_oom_gfp_mask = mask;
-			current->memcg_oom_order = order;
 		}
 		return false;
 	}