Re: [PATCH v6 3/6] mm/page_alloc: add support for initializing pageblock as isolated.

[Vlastimil Babka <vbabka@suse.cz>]

On 5/30/25 18:22, Zi Yan wrote:
> MIGRATE_ISOLATE is a standalone bit, so a pageblock cannot be initialized
> to just MIGRATE_ISOLATE. Add init_pageblock_migratetype() to enable
> initialize a pageblock with a migratetype and isolated.
> 
> Signed-off-by: Zi Yan <ziy@nvidia.com>
> Reviewed-by: Vlastimil Babka <vbabka@suse.cz>

> +void __meminit init_pageblock_migratetype(struct page *page,
> +					  enum migratetype migratetype,
> +					  bool isolate)
> +{
> +	unsigned long mask = MIGRATETYPE_MASK;
> +	unsigned long flags = migratetype;
> +
> +	if (unlikely(page_group_by_mobility_disabled &&
> +		     migratetype < MIGRATE_PCPTYPES))
> +		migratetype = MIGRATE_UNMOVABLE;
> +
> +#ifdef CONFIG_MEMORY_ISOLATION
> +	if (migratetype == MIGRATE_ISOLATE) {
> +		VM_WARN_ONCE(
> +			1,
> +			"Set isolate=true to isolate pageblock with a migratetype");
> +		return;
> +	}
> +	if (isolate) {
> +		mask = MIGRATETYPE_AND_ISO_MASK;
> +		flags |= BIT(PB_migrate_isolate);
> +	}
> +#endif
> +	__set_pfnblock_flags_mask(page, page_to_pfn(page), flags, mask);

Nit: I think this could have also used MIGRATETYPE_AND_ISO_MASK unconditionally?

> +}
> +
>  #ifdef CONFIG_DEBUG_VM
>  static int page_outside_zone_boundaries(struct zone *zone, struct page *page)
>  {