On 10/04/2011 04:48 PM, Eric Dumazet wrote:

Le mardi 04 octobre 2011 à 16:17 +0400, Glauber Costa a écrit :

quoted

This patch uses the "tcp_max_mem" field of the kmem_cgroup to
effectively control the amount of kernel memory pinned by a cgroup.

We have to make sure that none of the memory pressure thresholds
specified in the namespace are bigger than the current cgroup.

Signed-off-by: Glauber Costa<redacted>
CC: David S. Miller<davem@davemloft.net>
CC: Hiroyouki Kamezawa<redacted>
CC: Eric W. Biederman<redacted>
---

quoted

--- a/include/net/tcp.h
+++ b/include/net/tcp.h

@@ -256,6 +256,7 @@ extern int sysctl_tcp_thin_dupack;
  struct mem_cgroup;
  struct tcp_memcontrol {
  	/* per-cgroup tcp memory pressure knobs */
+	int tcp_max_memory;
  	atomic_long_t tcp_memory_allocated;
  	struct percpu_counter tcp_sockets_allocated;
  	/* those two are read-mostly, leave them at the end */

diff --git a/mm/memcontrol.c b/mm/memcontrol.c

So tcp_max_memory is an "int".

quoted

+static u64 tcp_read_limit(struct cgroup *cgrp, struct cftype *cft)
+{
+	struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp);
+	return memcg->tcp.tcp_max_memory<<  PAGE_SHIFT;
+}

1) Typical integer overflow here.

You need :

return ((u64)memcg->tcp.tcp_max_memory)<<  PAGE_SHIFT;

Thanks for spotting this, Eric.

2) Could you add const qualifiers when possible to your pointers ?

Well, I'll go over the patches again and see where I can add them.
Any specific place site you're concerned about?