linux-kernel - Re: [PATCH 11/21] mm: introduce freetype

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Message-ID: <DD7WWPE3YSPZ.1E51AQNHNEU2G@google.com>
Date: Thu, 02 Oct 2025 14:39:27 +0000
From: Brendan Jackman <jackmanb@...gle.com>
To: Dave Hansen <dave.hansen@...el.com>, Brendan Jackman <jackmanb@...gle.com>, 
	Andy Lutomirski <luto@...nel.org>, Lorenzo Stoakes <lorenzo.stoakes@...cle.com>, 
	"Liam R. Howlett" <Liam.Howlett@...cle.com>, Suren Baghdasaryan <surenb@...gle.com>, 
	Michal Hocko <mhocko@...e.com>, Johannes Weiner <hannes@...xchg.org>, Zi Yan <ziy@...dia.com>, 
	Axel Rasmussen <axelrasmussen@...gle.com>, Yuanchu Xie <yuanchu@...gle.com>, 
	Roman Gushchin <roman.gushchin@...ux.dev>
Cc: <peterz@...radead.org>, <bp@...en8.de>, <dave.hansen@...ux.intel.com>, 
	<mingo@...hat.com>, <tglx@...utronix.de>, <akpm@...ux-foundation.org>, 
	<david@...hat.com>, <derkling@...gle.com>, <junaids@...gle.com>, 
	<linux-kernel@...r.kernel.org>, <linux-mm@...ck.org>, <reijiw@...gle.com>, 
	<rientjes@...gle.com>, <rppt@...nel.org>, <vbabka@...e.cz>, <x86@...nel.org>, 
	<yosry.ahmed@...ux.dev>
Subject: Re: [PATCH 11/21] mm: introduce freetype_t

On Wed Oct 1, 2025 at 9:20 PM UTC, Dave Hansen wrote:
> On 9/24/25 07:59, Brendan Jackman wrote:
>> @@ -2234,7 +2235,7 @@ static bool should_proactive_compact_node(pg_data_t *pgdat)
>>  static enum compact_result __compact_finished(struct compact_control *cc)
>>  {
>>  	unsigned int order;
>> -	const int migratetype = cc->migratetype;
>> +	const freetype_t freetype = cc->freetype;
>
> Just as I'm scanning this series at a high level, this patch looks too
> big to me. There is too much mixing of mechanical changes like this
> s/int/freetype_t/ and s/migratetype/freetype/ with new functionality.
>
> I'd be looking for ways to split this up a lot more.

Ack. One avenue I didn't fully explore would be to break it into:

1. Introduce freetype_t as nothing else than an annoying wrapper around
   migratetype.

2. Add the sensitive field when ASI is compiled in. 

The reason I shied away from this, is that part 1 will look kinda weird,
because in some place I'll be switching the code to freetype while
others will still use migratetype (code that will never care about
sensitivity), and the distinction might not be obvious without first
reading part 2. I'll just have to try and write a good commit message I
suppose.