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Re: [PATCH v5 6/8] tcp buffer limitation: per-cgroup limit [message #43650 is a reply to message #43643]

Tue, 04 October 2011 12:48

Eric Dumazet
Messages: 36
Registered: July 2006

Member

Le mardi 04 octobre 2011 à 16:17 +0400, Glauber Costa a écrit :
> 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 <glommer@parallels.com>
> CC: David S. Miller <davem@davemloft.net>
> CC: Hiroyouki Kamezawa <kamezawa.hiroyu@jp.fujitsu.com>
> CC: Eric W. Biederman <ebiederm@xmission.com>
> ---

> --- 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".

> +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;

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

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[Message index]

		[PATCH v5 0/8] per-cgroup tcp buffer pressure settings By: Glauber Costa on Tue, 04 October 2011 12:17
		[PATCH v5 6/8] tcp buffer limitation: per-cgroup limit By: Glauber Costa on Tue, 04 October 2011 12:17
		Re: [PATCH v5 6/8] tcp buffer limitation: per-cgroup limit By: Eric Dumazet on Tue, 04 October 2011 12:48
		Re: [PATCH v5 6/8] tcp buffer limitation: per-cgroup limit By: Glauber Costa on Wed, 05 October 2011 08:08
		Re: [PATCH v5 6/8] tcp buffer limitation: per-cgroup limit By: Eric Dumazet on Wed, 05 October 2011 08:58
		Re: [PATCH v5 6/8] tcp buffer limitation: per-cgroup limit By: Glauber Costa on Thu, 06 October 2011 08:38
		[PATCH v5 3/8] foundations of per-cgroup memory pressure controlling. By: Glauber Costa on Tue, 04 October 2011 12:17
		[PATCH v5 7/8] Display current tcp memory allocation in kmem cgroup By: Glauber Costa on Tue, 04 October 2011 12:17
		[PATCH v5 2/8] socket: initial cgroup code. By: Glauber Costa on Tue, 04 October 2011 12:17
		[PATCH v5 5/8] per-netns ipv4 sysctl_tcp_mem By: Glauber Costa on Tue, 04 October 2011 12:17
		[PATCH v5 4/8] per-cgroup tcp buffers control By: Glauber Costa on Tue, 04 October 2011 12:17
		[PATCH v5 8/8] Disable task moving when using kernel memory accounting By: Glauber Costa on Tue, 04 October 2011 12:18
		Re: [PATCH v5 0/8] per-cgroup tcp buffer pressure settings By: KAMEZAWA Hiroyuki on Wed, 05 October 2011 00:29
		Re: [PATCH v5 0/8] per-cgroup tcp buffer pressure settings By: Glauber Costa on Wed, 05 October 2011 07:25
		Re: [PATCH v5 0/8] per-cgroup tcp buffer pressure settings By: KAMEZAWA Hiroyuki on Fri, 07 October 2011 08:05
		Re: [PATCH v5 0/8] per-cgroup tcp buffer pressure settings By: Glauber Costa on Fri, 07 October 2011 08:20
		Re: [PATCH v5 0/8] per-cgroup tcp buffer pressure settings By: KAMEZAWA Hiroyuki on Fri, 07 October 2011 08:55

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