linux-kernel - Re: [PATCH v2 04/28] mm: vmscan: prepare for the refactoring the move_folios_to

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Message-ID: <8d9592ea-988c-4c97-b059-a58afb05b3f3@linux.dev>
Date: Thu, 18 Dec 2025 17:31:07 +0800
From: Qi Zheng <qi.zheng@...ux.dev>
To: "David Hildenbrand (Red Hat)" <david@...nel.org>, hannes@...xchg.org,
 hughd@...gle.com, mhocko@...e.com, roman.gushchin@...ux.dev,
 shakeel.butt@...ux.dev, muchun.song@...ux.dev, lorenzo.stoakes@...cle.com,
 ziy@...dia.com, harry.yoo@...cle.com, imran.f.khan@...cle.com,
 kamalesh.babulal@...cle.com, axelrasmussen@...gle.com, yuanchu@...gle.com,
 weixugc@...gle.com, chenridong@...weicloud.com, mkoutny@...e.com,
 akpm@...ux-foundation.org, hamzamahfooz@...ux.microsoft.com,
 apais@...ux.microsoft.com, lance.yang@...ux.dev
Cc: linux-mm@...ck.org, linux-kernel@...r.kernel.org,
 cgroups@...r.kernel.org, Qi Zheng <zhengqi.arch@...edance.com>
Subject: Re: [PATCH v2 04/28] mm: vmscan: prepare for the refactoring the
 move_folios_to_lru()



On 12/18/25 5:04 PM, David Hildenbrand (Red Hat) wrote:
> On 12/17/25 08:27, Qi Zheng wrote:
>> From: Qi Zheng <zhengqi.arch@...edance.com>
>>
>> After refactoring the move_folios_to_lru(), its caller no longer needs to
>> hold the lruvec lock, the disabling IRQ is only for __count_vm_events()
>> and __mod_node_page_state().
>>
>> On the PREEMPT_RT kernel, the local_irq_disable() cannot be used. To
>> avoid using local_irq_disable() and reduce the critical section of
>> disabling IRQ, make all callers of move_folios_to_lru() use IRQ-safed
>> count_vm_events() and mod_node_page_state().
> 
> The patch description is a bit confusing for me.
> 
> I assume you mean something like
> 
> "Once we refactor move_folios_to_lru(), its callers will no longer have 
> to hold the lruvec lock; disabling IRQs is then only required for 
> __count_vm_events() and __mod_node_page_state().
> 
> To prepare for that, let's $YOURDETAILSHERE"

It is indeed clearer, will do in the next version.

>