Re: [patch] mm, memcg: store memcg name for oom kill logconsistency

[David Rientjes]

On Thu, 5 Sep 2013, Michal Hocko wrote:

> From 4cee36f56100f5689fe1ae22f468016ce5a0cbae Mon Sep 17 00:00:00 2001
> From: Michal Hocko <mhocko@xxxxxxx>
> Date: Thu, 5 Sep 2013 15:39:20 +0200
> Subject: [PATCH] memcg, oom: lock mem_cgroup_print_oom_info
> 
> mem_cgroup_print_oom_info uses a static buffer (memcg_name) to store the
> name of the cgroup. This is not safe as pointed out by David Rientjes
> because although memcg oom is locked for its hierarchy nothing prevents
> another parallel hierarchy to trigger oom as well and overwrite the
> already in-use buffer.
> 
> This patch introduces oom_info_lock hidden inside mem_cgroup_print_oom_info
> which is held throughout the function. It make access to memcg_name safe
> and as a bonus it also prevents parallel memcg ooms to interleave their
> statistics which would make the printed data hard to analyze otherwise.
> 
> Using the spinlock is OK here because this path is not hot and
> meaningful data is much more important.
> 
> Reported-by: David Rientjes <rientjes@xxxxxxxxxx>

Remove this.

> Signed-off-by: Michal Hocko <mhocko@xxxxxxx>
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