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

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Message-ID: <ZxStKvw6HwminDub@kernel.org>
Date: Sun, 20 Oct 2024 10:11:38 +0300
From: Mike Rapoport <rppt@...nel.org>
To: suhua <suhua.tanke@...il.com>
Cc: 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:
> Subject: memblock: Uniform initialization all reserved pages to MIGRATE_MOVABLE

I'd suggest:

memblock: uniformly initialize all reserved pages to MIGRATE_MOVABLE

> 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.

The struct page metadata is not freed with HVO, it is rather pages used for
vmemmap.
 
> 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:

Please add back the description of the hardware used for this test and how
much huge pages were allocated at boot.

> 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>

checkpatch.pl gives this warning:

WARNING: From:/Signed-off-by: email address mismatch: 'From: suhua <suhua.tanke@...il.com>' != 'Signed-off-by: suhua <suhua1@...gsoft.com>'
Please update the commit authorship or signed-off to match.

Also, Signed-off-by should use a known identity, i.e. Name Lastname.

> ---
>  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
> 

-- 
Sincerely yours,
Mike.