Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Date:   Wed, 4 Aug 2021 17:27:29 +0300
From:   "Kirill A. Shutemov" <kirill@shutemov.name>
To:     Yu Zhao <yuzhao@google.com>
Cc:     linux-mm@kvack.org, Andrew Morton <akpm@linux-foundation.org>,
        Hugh Dickins <hughd@google.com>,
        "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
        Matthew Wilcox <willy@infradead.org>,
        Vlastimil Babka <vbabka@suse.cz>,
        Yang Shi <shy828301@gmail.com>, Zi Yan <ziy@nvidia.com>,
        linux-kernel@vger.kernel.org, Shuang Zhai <zhais@google.com>
Subject: Re: [PATCH 3/3] mm: don't remap clean subpages when splitting
 isolated thp
Message-ID: <20210804142729.iqtslnn3utvqgec3@box.shutemov.name>
References: <20210731063938.1391602-1-yuzhao@google.com>
 <20210731063938.1391602-4-yuzhao@google.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20210731063938.1391602-4-yuzhao@google.com>
Precedence: bulk

On Sat, Jul 31, 2021 at 12:39:38AM -0600, Yu Zhao wrote:
> @@ -267,13 +308,19 @@ static bool remove_migration_pte(struct page *page, struct vm_area_struct *vma,
>   * Get rid of all migration entries and replace them by
>   * references to the indicated page.
>   */
> -void remove_migration_ptes(struct page *old, struct page *new, bool locked)
> +void remove_migration_ptes(struct page *old, struct page *new, bool locked, bool unmap_clean)
>  {
> +	struct rmap_walk_arg rmap_walk_arg = {
> +		.page = old,
> +		.unmap_clean = unmap_clean,
> +	};
>  	struct rmap_walk_control rwc = {
>  		.rmap_one = remove_migration_pte,
> -		.arg = old,
> +		.arg = &rmap_walk_arg,
>  	};

'old' pointer has few low always-zero bit :P

-- 
 Kirill A. Shutemov