[RFC 2/5] memcontrol: add boot option to enable memsw account on dfl

[Jingxiang Zeng]

From: Zeng Jingxiang <linuszeng@xxxxxxxxxxx>

Added cgroup.memsw_account_on_dfl startup parameter, which
is off by default. When enabled in cgroupv2 mode, the memory
accounting mode of swap will be reverted to cgroupv1 mode.

Signed-off-by: Zeng Jingxiang <linuszeng@xxxxxxxxxxx>
---
 include/linux/memcontrol.h |  4 +++-
 mm/memcontrol.c            | 11 +++++++++++
 2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index dcb087ee6e8d..96f2fad1c351 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -62,10 +62,12 @@ struct mem_cgroup_reclaim_cookie {
 
 #ifdef CONFIG_MEMCG
 
+DECLARE_STATIC_KEY_FALSE(memsw_account_on_dfl);
 /* Whether enable memory+swap account in cgroupv2 */
 static inline bool do_memsw_account_on_dfl(void)
 {
-	return IS_ENABLED(CONFIG_MEMSW_ACCOUNT_ON_DFL);
+	return IS_ENABLED(CONFIG_MEMSW_ACCOUNT_ON_DFL)
+				|| static_branch_unlikely(&memsw_account_on_dfl);
 }
 
 #define MEM_CGROUP_ID_SHIFT	16
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 768d6b15dbfa..c1171fb2bfd6 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -5478,3 +5478,14 @@ static int __init mem_cgroup_swap_init(void)
 subsys_initcall(mem_cgroup_swap_init);
 
 #endif /* CONFIG_SWAP */
+
+DEFINE_STATIC_KEY_FALSE(memsw_account_on_dfl);
+static int __init memsw_account_on_dfl_setup(char *s)
+{
+	if (!strcmp(s, "1"))
+		static_branch_enable(&memsw_account_on_dfl);
+	else if (!strcmp(s, "0"))
+		static_branch_disable(&memsw_account_on_dfl);
+	return 1;
+}
+__setup("cgroup.memsw_account_on_dfl=", memsw_account_on_dfl_setup);
+
\ No newline at end of file
-- 
2.41.1