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memcg: put a restriction on writing memory.force_empty

PATCH In review Li Zefan 3 participants 3 messages Mar 11, 2008

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Li Zefan

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#0 lore raw

PATCH 2/3 memcg: put a restriction on writing memory.force_empty

We can write whatever to memory.force_empty:

echo 999 > memory.force_empty
echo wow > memory.force_empty

This is odd, so let's make '1' to be the only valid value.

Signed-off-by Li Zefan <[email protected]>
---
 mm/memcontrol.c |   21 ++++++++++++---------
 1 files changed, 12 insertions(+), 9 deletions(-)
mm/memcontrol.c +12 -9
index eb681a6..6145031 100644
@@ -868,15 +868,18 @@ static ssize_t mem_cgroup_write(struct cgroup *cont, struct cftype *cft,
 				mem_cgroup_write_strategy);
 }
 
-static ssize_t mem_force_empty_write(struct cgroup *cont,
-				struct cftype *cft, struct file *file,
-				const char __user *userbuf,
-				size_t nbytes, loff_t *ppos)
+static int mem_force_empty_write(struct cgroup *cont, struct cftype *cft,
+				 u64 val)
 {
-	struct mem_cgroup *mem = mem_cgroup_from_cont(cont);
-	int ret = mem_cgroup_force_empty(mem);
-	if (!ret)
-		ret = nbytes;
+	struct mem_cgroup *mem;
+	int ret;
+
+	if (val != 1)
+		return -EINVAL;
+
+	mem = mem_cgroup_from_cont(cont);
+	ret = mem_cgroup_force_empty(mem);
+
 	return ret;
 }
 

@@ -935,7 +938,7 @@ static struct cftype mem_cgroup_files[] = {
 	},
 	{
 		.name = "force_empty",
-		.write = mem_force_empty_write,
+		.write_u64 = mem_force_empty_write,
 	},
 	{
 		.name = "stat",
Signature · 1 line
1.5.4.rc3
#1 lore raw
Quoted 6 lines · Li Zefan

We can write whatever to memory.force_empty:

echo 999 > memory.force_empty
echo wow > memory.force_empty

This is odd, so let's make '1' to be the only valid value.

I suspect as long as there is no unreasonable side-effect, writing 999 or wow should be OK.

Signature · 10 lines
	Warm Regards,
	Balbir Singh
	Linux Technology Center
	IBM, ISTL

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#2 lore raw
Quoted 11 lines · On Tue, 11 Mar 2008 15:45:06 +0530 Balbir Singh <[email protected]>…
Quoted 6 lines · Li Zefan

We can write whatever to memory.force_empty:

echo 999 > memory.force_empty
echo wow > memory.force_empty

This is odd, so let's make '1' to be the only valid value.

I suspect as long as there is no unreasonable side-effect, writing 999 or wow should be OK.

I agree with Balbir.

Thanks,
-Kame