From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <owner-linux-mm@kvack.org>
Date: Sat, 15 Dec 2018 11:51:12 +0100
From: Christoph Hellwig <hch@lst.de>
To: Richard Weinberger <richard@nod.at>
Cc: zhangjun <openzhangj@gmail.com>,
	Alexander Viro <viro@zeniv.linux.org.uk>,
	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
	"Darrick J . Wong" <darrick.wong@oracle.com>, hch@lst.de,
	bfoster@redhat.com, Dave Chinner <david@fromorbit.com>,
	akpm@linux-foundation.org, kirill.shutemov@linux.intel.com,
	mhocko@suse.com, n-horiguchi@ah.jp.nec.com,
	mgorman@techsingularity.net, aarcange@redhat.com,
	willy@infradead.org, linux@dominikbrodowski.net, linux-mm@kvack.org,
	Gao Xiang <gaoxiang25@huawei.com>
Subject: Re: [PATCH] fix page_count in ->iomap_migrate_page()
Message-ID: <20181215105112.GC1575@lst.de>
References: <1544766961-3492-1-git-send-email-openzhangj@gmail.com> <1618433.IpySj692Hd@blindfold>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <1618433.IpySj692Hd@blindfold>
Sender: owner-linux-mm@kvack.org
List-ID: <linux-fsdevel.vger.kernel.org>

FYI, for iomap we got a patch to just increment the page count when
setting the private data, and it finally got merged into mainline after
a while.

Not that it totally makes sense to me, but it is what it is.  It would
just be nice if set_page_private took care of it and we had a
clear_page_private to undo it, making the whole scheme at lot more
obvious.