memcg: Add static key for memcg kswapd

hulk inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I4IMAK?from=project-issue
CVE: NA

--------

This patch adds a default-false static key to disable memcg kswapd
feature. User can enable by set memcg_kswapd in cmdline.
Signed-off-by: NLu Jialin <lujialin4@huawei.com>
Reviewed-by: Nweiyang wang <wangweiyang2@huawei.com>
Reviewed-by: NKefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

include/linux/memcontrol.h

@@ -1863,6 +1863,9 @@ static inline void mem_cgroup_flush_foreign(struct bdi_writeback *wb)
 
 #endif	/* CONFIG_CGROUP_WRITEBACK */
 
+extern struct static_key_false memcg_kswapd_key;
+#define mem_cgroup_kswapd_enabled static_branch_unlikely(&memcg_kswapd_key)
+
 struct sock;
 bool mem_cgroup_charge_skmem(struct mem_cgroup *memcg, unsigned int nr_pages);
 void mem_cgroup_uncharge_skmem(struct mem_cgroup *memcg, unsigned int nr_pages);

mm/memcontrol.c

@@ -96,6 +96,10 @@ bool cgroup_memory_noswap __read_mostly;
 static DECLARE_WAIT_QUEUE_HEAD(memcg_cgwb_frn_waitq);
 #endif
 
+static bool cgroup_memory_kswapd = false;
+DEFINE_STATIC_KEY_FALSE(memcg_kswapd_key);
+EXPORT_SYMBOL(memcg_kswapd_key);
+
 /* Whether legacy memory+swap accounting is active */
 static bool do_memsw_account(void)
 {
@@ -2364,10 +2368,15 @@ static void high_work_func(struct work_struct *work)
 {
 	struct mem_cgroup *memcg;
 
-	current->flags |= PF_SWAPWRITE | PF_MEMALLOC | PF_KSWAPD;
-	memcg = container_of(work, struct mem_cgroup, high_work);
-	reclaim_high(memcg, MEMCG_CHARGE_BATCH, GFP_KERNEL);
-	current->flags &= ~(PF_SWAPWRITE | PF_MEMALLOC | PF_KSWAPD);
+	if (mem_cgroup_kswapd_enabled) {
+		current->flags |= PF_SWAPWRITE | PF_MEMALLOC | PF_KSWAPD;
+		memcg = container_of(work, struct mem_cgroup, high_work);
+		reclaim_high(memcg, MEMCG_CHARGE_BATCH, GFP_KERNEL);
+		current->flags &= ~(PF_SWAPWRITE | PF_MEMALLOC | PF_KSWAPD);
+	} else {
+		memcg = container_of(work, struct mem_cgroup, high_work);
+		reclaim_high(memcg, MEMCG_CHARGE_BATCH, GFP_KERNEL);
+	}
 }
 
 /*
@@ -2537,11 +2546,17 @@ void mem_cgroup_handle_over_high(void)
 	 * memory.high is currently batched, whereas memory.max and the page
 	 * allocator run every time an allocation is made.
 	 */
-	current->flags |= PF_SWAPWRITE | PF_MEMALLOC | PF_KSWAPD;
-	nr_reclaimed = reclaim_high(memcg,
-				    in_retry ? SWAP_CLUSTER_MAX : nr_pages,
-				    GFP_KERNEL);
-	current->flags &= ~(PF_SWAPWRITE | PF_MEMALLOC | PF_KSWAPD);
+	if (mem_cgroup_kswapd_enabled) {
+		current->flags |= PF_SWAPWRITE | PF_MEMALLOC | PF_KSWAPD;
+		nr_reclaimed = reclaim_high(memcg,
+					    in_retry ? SWAP_CLUSTER_MAX : nr_pages,
+					    GFP_KERNEL);
+		current->flags &= ~(PF_SWAPWRITE | PF_MEMALLOC | PF_KSWAPD);
+	} else {
+		nr_reclaimed = reclaim_high(memcg,
+					    in_retry ? SWAP_CLUSTER_MAX : nr_pages,
+					    GFP_KERNEL);
+	}
 
 	/*
 	 * memory.high is breached and reclaim is unable to keep up. Throttle
@@ -5477,6 +5492,9 @@ mem_cgroup_css_alloc(struct cgroup_subsys_state *parent_css)
 	struct mem_cgroup *memcg, *old_memcg;
 	long error = -ENOMEM;
 
+	if (cgroup_memory_kswapd)
+		static_branch_enable(&memcg_kswapd_key);
+
 	old_memcg = set_active_memcg(parent);
 	memcg = mem_cgroup_alloc();
 	set_active_memcg(old_memcg);
@@ -7280,6 +7298,13 @@ static int __init cgroup_memory(char *s)
 }
 __setup("cgroup.memory=", cgroup_memory);
 
+static int __init memcg_kswapd(char *s)
+{
+	cgroup_memory_kswapd = true;
+	return 0;
+}
+__setup("memcg_kswapd", memcg_kswapd);
+
 /*
  * subsys_initcall() for memory controller.
  *

mm/vmscan.c

@@ -2843,8 +2843,9 @@ static bool is_memcg_kswapd_stopped(struct scan_control *sc)
 	bool is_stop = false;
 	unsigned long stop_flag = 0;
 
-	if (!cgroup_reclaim(sc))
+	if (!cgroup_reclaim(sc) || !mem_cgroup_kswapd_enabled)
 		return false;
+
 	if (memcg->memory.max == PAGE_COUNTER_MAX)
 		stop_flag = memcg->memory.high / 6;
 	else