linux-kernel - Re: [PATCH] memblock: Uniform initialization all reserved pages to MIGRATE

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Message-ID: <20241019015738.5oy7l6fzbmpeixgk@master>
Date: Sat, 19 Oct 2024 01:57:38 +0000
From: Wei Yang <richard.weiyang@...il.com>
To: suhua <suhua.tanke@...il.com>
Cc: rppt@...nel.org, akpm@...ux-foundation.org, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org, suhua <suhua1@...gsoft.com>
Subject: Re: [PATCH] memblock: Uniform initialization all reserved pages to
 MIGRATE_MOVABLE

On Thu, Oct 17, 2024 at 02:44:49PM +0800, suhua wrote:
>Currently when CONFIG_DEFERRED_STRUCT_PAGE_INIT is not set, the reserved
>pages are initialized to MIGRATE_MOVABLE by default in memmap_init.
>
>Reserved memory mainly stores the metadata of struct page. When
>HUGETLB_PAGE_OPTIMIZE_VMEMMAP_DEFAULT_ON=Y and hugepages are allocated,
>the memory occupied by the struct page metadata will be freed.
>
>Before this patch:
>when CONFIG_DEFERRED_STRUCT_PAGE_INIT is not set, the freed memory was
>placed on the Movable list;
>When CONFIG_DEFERRED_STRUCT_PAGE_INIT=Y, the freed memory was placed on
>the Unmovable list.
>
>After this patch, the freed memory is placed on the Movable list
>regardless of whether CONFIG_DEFERRED_STRUCT_PAGE_INIT is set.
>
>Eg:
>echo 500000 > /proc/sys/vm/nr_hugepages
>cat /proc/pagetypeinfo
>
>before：
>Free pages count per migrate type at order       0      1      2      3      4      5      6      7      8      9     10
>…
>Node    0, zone   Normal, type    Unmovable     51      2      1     28     53     35     35     43     40     69   3852
>Node    0, zone   Normal, type      Movable   6485   4610    666    202    200    185    208     87     54      2    240
>Node    0, zone   Normal, type  Reclaimable      2      2      1     23     13      1      2      1      0      1      0
>Node    0, zone   Normal, type   HighAtomic      0      0      0      0      0      0      0      0      0      0      0
>Node    0, zone   Normal, type      Isolate      0      0      0      0      0      0      0      0      0      0      0
>Unmovable ≈ 15GB
>
>after：
>Free pages count per migrate type at order       0      1      2      3      4      5      6      7      8      9     10
>…
>Node    0, zone   Normal, type    Unmovable      0      1      1      0      0      0      0      1      1      1      0
>Node    0, zone   Normal, type      Movable   1563   4107   1119    189    256    368    286    132    109      4   3841
>Node    0, zone   Normal, type  Reclaimable      2      2      1     23     13      1      2      1      0      1      0
>Node    0, zone   Normal, type   HighAtomic      0      0      0      0      0      0      0      0      0      0      0
>Node    0, zone   Normal, type      Isolate      0      0      0      0      0      0      0      0      0      0      0
>
>Signed-off-by: suhua <suhua1@...gsoft.com>

Looks good to me.

Reviewed-by: Wei Yang <richard.weiyang@...il.com>

>---
> mm/mm_init.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
>diff --git a/mm/mm_init.c b/mm/mm_init.c
>index 4ba5607aaf19..6dbf2df23eee 100644
>--- a/mm/mm_init.c
>+++ b/mm/mm_init.c
>@@ -722,6 +722,10 @@ static void __meminit init_reserved_page(unsigned long pfn, int nid)
> 		if (zone_spans_pfn(zone, pfn))
> 			break;
> 	}
>+
>+	if (pageblock_aligned(pfn))
>+		set_pageblock_migratetype(pfn_to_page(pfn), MIGRATE_MOVABLE);
>+
> 	__init_single_page(pfn_to_page(pfn), pfn, zid, nid);
> }
> #else
>-- 
>2.34.1
>

-- 
Wei Yang
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