Re: [PATCH 2/3] mm: hugetlb: make the hugetlb migration strategy consistent

From: Oscar Salvador <osalvador@suse.de>
To: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: akpm@linux-foundation.org, muchun.song@linux.dev,
	david@redhat.com, linmiaohe@huawei.com, naoya.horiguchi@nec.com,
	mhocko@kernel.org, linux-mm@kvack.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/3] mm: hugetlb: make the hugetlb migration strategy consistent
Date: Tue, 27 Feb 2024 16:17:16 +0100	[thread overview]
Message-ID: <Zd38_AYtr9QKp-F6@localhost.localdomain> (raw)
In-Reply-To: <bdca97e6c59f1b58f09e18defac0c47d1e38f44b.1709041586.git.baolin.wang@linux.alibaba.com>

On Tue, Feb 27, 2024 at 09:52:26PM +0800, Baolin Wang wrote:

> --- a/mm/hugetlb.c
> +++ b/mm/hugetlb.c
> @@ -2567,13 +2567,38 @@ static struct folio *alloc_surplus_hugetlb_folio(struct hstate *h,
>  }
>  
>  static struct folio *alloc_migrate_hugetlb_folio(struct hstate *h, gfp_t gfp_mask,
> -				     int nid, nodemask_t *nmask)
> +				     int nid, nodemask_t *nmask, int reason)

I still dislike taking the reason argument this far, and I'd rather have
this as a boolean specifing whether we allow fallback on other nodes.
That would mean parsing the reason in alloc_migration_target().
If we don't add a new helper e.g: gfp_allow_fallback(), we can just do
it right there an opencode it with a e.g: macro etc.

Although doing it in an inline helper might help hiding these details.

That's my take on this, but let's see what others have to say.

-- 
Oscar Salvador
SUSE Labs