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Date:   Tue, 23 Mar 2021 02:11:29 +0000
From:   Matthew Wilcox <willy@infradead.org>
To:     Peter Xu <peterx@redhat.com>
Cc:     linux-kernel@vger.kernel.org, linux-mm@kvack.org,
        "Kirill A . Shutemov" <kirill@shutemov.name>,
        Jerome Glisse <jglisse@redhat.com>,
        Mike Kravetz <mike.kravetz@oracle.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Axel Rasmussen <axelrasmussen@google.com>,
        Hugh Dickins <hughd@google.com>,
        Nadav Amit <nadav.amit@gmail.com>,
        Andrea Arcangeli <aarcange@redhat.com>,
        Mike Rapoport <rppt@linux.vnet.ibm.com>
Subject: Re: [PATCH 07/23] mm: Introduce zap_details.zap_flags
Message-ID: <20210323021129.GZ1719932@casper.infradead.org>
References: <20210323004912.35132-1-peterx@redhat.com>
 <20210323004912.35132-8-peterx@redhat.com>
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On Mon, Mar 22, 2021 at 08:48:56PM -0400, Peter Xu wrote:
> +/* Whether to check page->mapping when zapping */
> +#define  ZAP_FLAG_CHECK_MAPPING             BIT(0)
> +
>  /*
>   * Parameter block passed down to zap_pte_range in exceptional cases.
>   */
>  struct zap_details {
> -	struct address_space *check_mapping;	/* Check page->mapping if set */
> +	struct address_space *zap_mapping;	/* Check page->mapping if set */

Now the comment is wrong.  It used to mean "If this is NULL, zap pages
with any mapping", but now it's always set, and the decision about whether
to check the mapping is in the flag.

Honestly, I'd remove the comments from both these members.  They don't add
anything to understandability now.

> +	unsigned long zap_flags;		/* Special flags for zapping */
>  };