linux-kernel - Re: [patch 3/3] mm: memory: merge shared-writable dirtying branches in do_wp

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Message-ID: <20141202120824.GD22683@node.dhcp.inet.fi>
Date:	Tue, 2 Dec 2014 14:08:24 +0200
From:	"Kirill A. Shutemov" <kirill@...temov.name>
To:	Johannes Weiner <hannes@...xchg.org>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Tejun Heo <tj@...nel.org>, Hugh Dickins <hughd@...gle.com>,
	Michel Lespinasse <walken@...gle.com>, Jan Kara <jack@...e.cz>,
	linux-mm@...ck.org, linux-fsdevel@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [patch 3/3] mm: memory: merge shared-writable dirtying branches
 in do_wp_page()

On Mon, Dec 01, 2014 at 05:58:02PM -0500, Johannes Weiner wrote:
> Whether there is a vm_ops->page_mkwrite or not, the page dirtying is
> pretty much the same.  Make sure the page references are the same in
> both cases, then merge the two branches.
> 
> It's tempting to go even further and page-lock the !page_mkwrite case,
> to get it in line with everybody else setting the page table and thus
> further simplify the model.  But that's not quite compelling enough to
> justify dropping the pte lock, then relocking and verifying the entry
> for filesystems without ->page_mkwrite, which notably includes tmpfs.
> Leave it for now and lock the page late in the !page_mkwrite case.
> 
> Signed-off-by: Johannes Weiner <hannes@...xchg.org>

This would conflict with other patchset of do_wp_page() cleanups, but look
good.

Acked-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>

-- 
 Kirill A. Shutemov
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