Re: [PATCH] mm: replace is_zero_pfn with is_huge_zero_pmd for thp

From: Matthew Wilcox <willy@infradead.org>
To: Yu Zhao <yuzhao@google.com>
Cc: "Andrew Morton" <akpm@linux-foundation.org>,
	"Ralph Campbell" <rcampbell@nvidia.com>,
	"Jérôme Glisse" <jglisse@redhat.com>,
	"Will Deacon" <will@kernel.org>,
	"Peter Zijlstra" <peterz@infradead.org>,
	"Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com>,
	"Dave Airlie" <airlied@redhat.com>,
	"Thomas Hellstrom" <thellstrom@vmware.com>,
	"Souptick Joarder" <jrdr.linux@gmail.com>,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	"Gerald Schaefer" <gerald.schaefer@de.ibm.com>
Subject: Re: [PATCH] mm: replace is_zero_pfn with is_huge_zero_pmd for thp
Date: Mon, 26 Aug 2019 06:18:58 -0700	[thread overview]
Message-ID: <20190826131858.GB15933@bombadil.infradead.org> (raw)
In-Reply-To: <20190825200621.211494-1-yuzhao@google.com>

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@google.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
> 