linux-kernel - Re: [PATCH 08/10] hugetlb: remove unneeded SetHPageVmemmapOptimized()

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Message-Id: <A1ED2200-136D-477E-B1EC-E61E6B75931B@linux.dev>
Date:   Sat, 27 Aug 2022 09:35:52 +0800
From:   Muchun Song <muchun.song@...ux.dev>
To:     Miaohe Lin <linmiaohe@...wei.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Mike Kravetz <mike.kravetz@...cle.com>,
        Muchun Song <songmuchun@...edance.com>,
        Linux MM <linux-mm@...ck.org>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 08/10] hugetlb: remove unneeded SetHPageVmemmapOptimized()



> On Aug 26, 2022, at 17:24, Miaohe Lin <linmiaohe@...wei.com> wrote:
> 
> If code reaches here, it's guaranteed that HPageVmemmapOptimized is set
> for the hugetlb page (or VM_BUG_ON_PAGE() will complain about it). It's

Hi Miaohe,

Right.

> unnecessary to set it again.

No, I suppose you didn’t test this patch since it does not work. The
HPageVmemmapOptimized is cleared in the above code of line
(set_page_private(page, 0)). So NAck.

Thanks,
Muchun

> 
> Signed-off-by: Miaohe Lin <linmiaohe@...wei.com>
> ---
> mm/hugetlb.c | 1 -
> 1 file changed, 1 deletion(-)
> 
> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> index 7934188bbed0..b432a00061e3 100644
> --- a/mm/hugetlb.c
> +++ b/mm/hugetlb.c
> @@ -1520,7 +1520,6 @@ static void add_hugetlb_page(struct hstate *h, struct page *page,
> 
> 	set_compound_page_dtor(page, HUGETLB_PAGE_DTOR);
> 	set_page_private(page, 0);
> -	SetHPageVmemmapOptimized(page);
> 
> 	/*
> 	 * This page is about to be managed by the hugetlb allocator and
> -- 
> 2.23.0
> 
>