linux-kernel - Re: [PATCH v3 4/4] mm/page_isolation: remove migratetype parameter from more functions.

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Message-ID: <EB345ABF-CEAF-44CC-B144-39CE50354C36@nvidia.com>
Date: Thu, 08 May 2025 18:15:52 -0400
From: Zi Yan <ziy@...dia.com>
To: Johannes Weiner <hannes@...xchg.org>
Cc: David Hildenbrand <david@...hat.com>, linux-mm@...ck.org,
 Andrew Morton <akpm@...ux-foundation.org>,
 Oscar Salvador <osalvador@...e.de>, Vlastimil Babka <vbabka@...e.cz>,
 Baolin Wang <baolin.wang@...ux.alibaba.com>,
 "Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>,
 Mel Gorman <mgorman@...hsingularity.net>,
 Suren Baghdasaryan <surenb@...gle.com>, Michal Hocko <mhocko@...e.com>,
 Brendan Jackman <jackmanb@...gle.com>, Richard Chang <richardycc@...gle.com>,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 4/4] mm/page_isolation: remove migratetype parameter
 from more functions.

On 8 May 2025, at 17:11, Johannes Weiner wrote:

> On Wed, May 07, 2025 at 05:10:59PM -0400, Zi Yan wrote:
>> @@ -22,8 +22,17 @@ static inline bool is_migrate_isolate(int migratetype)
>>  }
>>  #endif
>>
>> -#define MEMORY_OFFLINE	0x1
>> -#define REPORT_FAILURE	0x2
>> +/*
>> + * Isolation flags:
>> + * MEMORY_OFFLINE - isolate to offline (!allocate) memory e.g., skip over
>> + *		    PageHWPoison() pages and PageOffline() pages.
>> + * REPORT_FAILURE - report details about the failure to isolate the range
>> + * CMA_ALLOCATION - isolate for CMA allocations
>> + */
>> +typedef unsigned int __bitwise isol_flags_t;
>> +#define MEMORY_OFFLINE		((__force isol_flags_t)BIT(0))
>> +#define REPORT_FAILURE		((__force isol_flags_t)BIT(1))
>> +#define CMA_ALLOCATION		((__force isol_flags_t)BIT(2))
>
> Should this be a mode enum instead? MEMORY_OFFLINE and CMA_ALLOCATION
> are exclusive modes AFAICS. REPORT_FAILURE is a flag, but it's only
> used by MEMORY_OFFLINE, so probably better to make it a part of that
> instead of having both a mode and a flag field.

Yes. Will use an enum for MEMORY_OFFLINE and CMA_ALLOCATION and
make REPORT_FAILURE as a separate flag. Thanks for the feedback.

--
Best Regards,
Yan, Zi