From mboxrd@z Thu Jan  1 00:00:00 1970
From: Johannes Weiner <hannes-druUgvl0LCNAfugRpC6u6w@public.gmane.org>
Subject: Re: [PATCH -mm -v10 1/3] mm, THP, swap: Delay splitting THP during
 swap out
Date: Mon, 1 May 2017 12:44:30 +0200
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To: Minchan Kim <minchan-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
Cc: "Huang, Ying" <ying.huang-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>, Andrew Morton <akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>, linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Andrea Arcangeli <aarcange-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>, Ebru Akagunduz <ebru.akagunduz-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>, Michal Hocko <mhocko-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>, Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>, Hugh Dickins <hughd-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>, Shaohua Li <shli-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>, Rik van Riel <riel-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>, cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org

On Fri, Apr 28, 2017 at 05:40:44PM +0900, Minchan Kim wrote:
> However, get_swap_page is ugly now. The caller should take care of
> failure and should retry after split. I hope get_swap_page includes
> split and retry logic in itself without reling on the caller.

I think this makes the interface terrible. It's an allocation function
to which you pass a reference object for size - and if the allocation
doesn't succeed it'll split your reference object to make it fit?

That's a nasty side effect for this function to have.