memcg: always create memsw files if CONFIG_CGROUP_MEM_RES_CTLR_SWAP
Instead of conditioning creation of memsw files on do_swap_account,
always create the files if compiled-in and fail read/write attempts
with -EOPNOTSUPP if !do_swap_account.
This is suggested by KAMEZAWA to simplify memcg file creation so that
it can use cgroup->subsys_cftypes.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Li Zefan <lizf@cn.fujitsu.com>
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 7d698df..97a45b3 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -3879,14 +3879,21 @@
return val << PAGE_SHIFT;
}
-static u64 mem_cgroup_read(struct cgroup *cont, struct cftype *cft)
+static ssize_t mem_cgroup_read(struct cgroup *cont, struct cftype *cft,
+ struct file *file, char __user *buf,
+ size_t nbytes, loff_t *ppos)
{
struct mem_cgroup *memcg = mem_cgroup_from_cont(cont);
+ char str[64];
u64 val;
- int type, name;
+ int type, name, len;
type = MEMFILE_TYPE(cft->private);
name = MEMFILE_ATTR(cft->private);
+
+ if (!do_swap_account && type == _MEMSWAP)
+ return -EOPNOTSUPP;
+
switch (type) {
case _MEM:
if (name == RES_USAGE)
@@ -3903,7 +3910,9 @@
default:
BUG();
}
- return val;
+
+ len = scnprintf(str, sizeof(str), "%llu\n", (unsigned long long)val);
+ return simple_read_from_buffer(buf, nbytes, ppos, str, len);
}
/*
* The user of this function is...
@@ -3919,6 +3928,10 @@
type = MEMFILE_TYPE(cft->private);
name = MEMFILE_ATTR(cft->private);
+
+ if (!do_swap_account && type == _MEMSWAP)
+ return -EOPNOTSUPP;
+
switch (name) {
case RES_LIMIT:
if (mem_cgroup_is_root(memcg)) { /* Can't set limit on root */
@@ -3984,12 +3997,15 @@
static int mem_cgroup_reset(struct cgroup *cont, unsigned int event)
{
- struct mem_cgroup *memcg;
+ struct mem_cgroup *memcg = mem_cgroup_from_cont(cont);
int type, name;
- memcg = mem_cgroup_from_cont(cont);
type = MEMFILE_TYPE(event);
name = MEMFILE_ATTR(event);
+
+ if (!do_swap_account && type == _MEMSWAP)
+ return -EOPNOTSUPP;
+
switch (name) {
case RES_MAX_USAGE:
if (type == _MEM)
@@ -4655,7 +4671,7 @@
{
.name = "usage_in_bytes",
.private = MEMFILE_PRIVATE(_MEM, RES_USAGE),
- .read_u64 = mem_cgroup_read,
+ .read = mem_cgroup_read,
.register_event = mem_cgroup_usage_register_event,
.unregister_event = mem_cgroup_usage_unregister_event,
},
@@ -4663,25 +4679,25 @@
.name = "max_usage_in_bytes",
.private = MEMFILE_PRIVATE(_MEM, RES_MAX_USAGE),
.trigger = mem_cgroup_reset,
- .read_u64 = mem_cgroup_read,
+ .read = mem_cgroup_read,
},
{
.name = "limit_in_bytes",
.private = MEMFILE_PRIVATE(_MEM, RES_LIMIT),
.write_string = mem_cgroup_write,
- .read_u64 = mem_cgroup_read,
+ .read = mem_cgroup_read,
},
{
.name = "soft_limit_in_bytes",
.private = MEMFILE_PRIVATE(_MEM, RES_SOFT_LIMIT),
.write_string = mem_cgroup_write,
- .read_u64 = mem_cgroup_read,
+ .read = mem_cgroup_read,
},
{
.name = "failcnt",
.private = MEMFILE_PRIVATE(_MEM, RES_FAILCNT),
.trigger = mem_cgroup_reset,
- .read_u64 = mem_cgroup_read,
+ .read = mem_cgroup_read,
},
{
.name = "stat",
@@ -4721,14 +4737,11 @@
.mode = S_IRUGO,
},
#endif
-};
-
#ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP
-static struct cftype memsw_cgroup_files[] = {
{
.name = "memsw.usage_in_bytes",
.private = MEMFILE_PRIVATE(_MEMSWAP, RES_USAGE),
- .read_u64 = mem_cgroup_read,
+ .read = mem_cgroup_read,
.register_event = mem_cgroup_usage_register_event,
.unregister_event = mem_cgroup_usage_unregister_event,
},
@@ -4736,35 +4749,22 @@
.name = "memsw.max_usage_in_bytes",
.private = MEMFILE_PRIVATE(_MEMSWAP, RES_MAX_USAGE),
.trigger = mem_cgroup_reset,
- .read_u64 = mem_cgroup_read,
+ .read = mem_cgroup_read,
},
{
.name = "memsw.limit_in_bytes",
.private = MEMFILE_PRIVATE(_MEMSWAP, RES_LIMIT),
.write_string = mem_cgroup_write,
- .read_u64 = mem_cgroup_read,
+ .read = mem_cgroup_read,
},
{
.name = "memsw.failcnt",
.private = MEMFILE_PRIVATE(_MEMSWAP, RES_FAILCNT),
.trigger = mem_cgroup_reset,
- .read_u64 = mem_cgroup_read,
+ .read = mem_cgroup_read,
},
-};
-
-static int register_memsw_files(struct cgroup *cont, struct cgroup_subsys *ss)
-{
- if (!do_swap_account)
- return 0;
- return cgroup_add_files(cont, ss, memsw_cgroup_files,
- ARRAY_SIZE(memsw_cgroup_files));
-};
-#else
-static int register_memsw_files(struct cgroup *cont, struct cgroup_subsys *ss)
-{
- return 0;
-}
#endif
+};
static int alloc_mem_cgroup_per_zone_info(struct mem_cgroup *memcg, int node)
{
@@ -5047,9 +5047,6 @@
ARRAY_SIZE(mem_cgroup_files));
if (!ret)
- ret = register_memsw_files(cont, ss);
-
- if (!ret)
ret = register_kmem_files(cont, ss);
return ret;
