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Subject: Re: [PATCH v3 3/7] mm/lru: replace pgdat lru_lock with lruvec lock
To:     Matthew Wilcox <willy@infradead.org>
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From:   Alex Shi <alex.shi@linux.alibaba.com>
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Date:   Tue, 19 Nov 2019 18:08:04 +0800
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在 2019/11/18 下午8:31, Matthew Wilcox 写道:
>> Thanks for comments, Shakeel.
>>
>> lruvec lifetime is same as memcg, which allocted in mem_cgroup_alloc()->alloc_mem_cgroup_per_node_info()
>> I have read Hugh's patchset, even not every lines. But what's point of you here?
> I believe Shakeel's point is that here:
> 
> struct lruvec *mem_cgroup_page_lruvec(struct page *page, struct pglist_data *pgdat)
> {
> ...
>         memcg = page->mem_cgroup;
> 
> there is nothing pinning the memcg, and it could be freed before
> dereferencing memcg->nodeinfo in mem_cgroup_page_nodeinfo().

That's right! I will send the fix patches for review. 
Thanks a lot!