Re: [PATCH] memcg: take reference before releasing rcu_read_lock

[Li Zefan]

On 2013/3/29 18:48, Glauber Costa wrote:
> On 03/29/2013 02:28 PM, Li Zefan wrote:
>> The memcg is not referenced, so it can be destroyed at anytime right
>> after we exit rcu read section, so it's not safe to access it.
>>
>> To fix this, we call css_tryget() to get a reference while we're still
>> in rcu read section.
>>
>> This also removes a bogus comment above __memcg_create_cache_enqueue().
>>
> Out of curiosity, did you see that happening ?
> 

Just by code inspection. This is not the only place you use RCU in this
wrong way. Remember the last patch I sent? ;)

> Theoretically, the race you describe seem real, and the fix is sound.
> 

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