linux-kernel - Re: [PATCH] mm: replace is_zero_pfn with is_huge_zero

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Date:   Mon, 26 Aug 2019 06:18:58 -0700
From:   Matthew Wilcox <willy@...radead.org>
To:     Yu Zhao <yuzhao@...gle.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Ralph Campbell <rcampbell@...dia.com>,
        Jérôme Glisse <jglisse@...hat.com>,
        Will Deacon <will@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        "Aneesh Kumar K . V" <aneesh.kumar@...ux.ibm.com>,
        Dave Airlie <airlied@...hat.com>,
        Thomas Hellstrom <thellstrom@...are.com>,
        Souptick Joarder <jrdr.linux@...il.com>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org,
        Gerald Schaefer <gerald.schaefer@...ibm.com>
Subject: Re: [PATCH] mm: replace is_zero_pfn with is_huge_zero_pmd for thp


Why did you not cc Gerald who wrote the patch?  You can't just
run get_maintainers.pl and call it good.

On Sun, Aug 25, 2019 at 02:06:21PM -0600, Yu Zhao wrote:
> For hugely mapped thp, we use is_huge_zero_pmd() to check if it's
> zero page or not.
> 
> We do fill ptes with my_zero_pfn() when we split zero thp pmd, but
>  this is not what we have in vm_normal_page_pmd().
> pmd_trans_huge_lock() makes sure of it.
> 
> This is a trivial fix for /proc/pid/numa_maps, and AFAIK nobody
> complains about it.
> 
> Signed-off-by: Yu Zhao <yuzhao@...gle.com>
> ---
>  mm/memory.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/mm/memory.c b/mm/memory.c
> index e2bb51b6242e..ea3c74855b23 100644
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -654,7 +654,7 @@ struct page *vm_normal_page_pmd(struct vm_area_struct *vma, unsigned long addr,
>  
>  	if (pmd_devmap(pmd))
>  		return NULL;
> -	if (is_zero_pfn(pfn))
> +	if (is_huge_zero_pmd(pmd))
>  		return NULL;
>  	if (unlikely(pfn > highest_memmap_pfn))
>  		return NULL;
> -- 
> 2.23.0.187.g17f5b7556c-goog
>