linux-kernel - Re: [PATCH v1 11/26] mm: page_io: prevent memory cgroup release in page

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Message-ID: <0addc62f-e0b3-456e-b172-9216a6d2b8d5@linux.dev>
Date: Thu, 20 Nov 2025 21:34:08 +0800
From: Qi Zheng <qi.zheng@...ux.dev>
To: Harry Yoo <harry.yoo@...cle.com>
Cc: hannes@...xchg.org, hughd@...gle.com, mhocko@...e.com,
 roman.gushchin@...ux.dev, shakeel.butt@...ux.dev, muchun.song@...ux.dev,
 david@...hat.com, lorenzo.stoakes@...cle.com, ziy@...dia.com,
 imran.f.khan@...cle.com, kamalesh.babulal@...cle.com,
 axelrasmussen@...gle.com, yuanchu@...gle.com, weixugc@...gle.com,
 akpm@...ux-foundation.org, linux-mm@...ck.org, linux-kernel@...r.kernel.org,
 cgroups@...r.kernel.org, Muchun Song <songmuchun@...edance.com>,
 Qi Zheng <zhengqi.arch@...edance.com>
Subject: Re: [PATCH v1 11/26] mm: page_io: prevent memory cgroup release in
 page_io module



On 11/19/25 5:26 PM, Harry Yoo wrote:
> On Tue, Oct 28, 2025 at 09:58:24PM +0800, Qi Zheng wrote:
>> From: Muchun Song <songmuchun@...edance.com>
>>
>> In the near future, a folio will no longer pin its corresponding
>> memory cgroup. To ensure safety, it will only be appropriate to
>> hold the rcu read lock or acquire a reference to the memory cgroup
>> returned by folio_memcg(), thereby preventing it from being released.
>>
>> In the current patch, the rcu read lock is employed to safeguard
>> against the release of the memory cgroup in swap_writepage() and
> 
> nit:                                          ^ swap_writeout()

will fix it.

> 
>> bio_associate_blkg_from_page().
>>
>> This serves as a preparatory measure for the reparenting of the
>> LRU pages.
>>
>> Signed-off-by: Muchun Song <songmuchun@...edance.com>
>> Signed-off-by: Qi Zheng <zhengqi.arch@...edance.com>
>> ---
> 
> Looks good to me,
> Reviewed-by: Harry Yoo <harry.yoo@...cle.com>

Thanks!

>