From mboxrd@z Thu Jan 1 00:00:00 1970 From: Michal Hocko Subject: Re: [v2 PATCH] move_pages.2: Returning positive value is a new error case Date: Thu, 30 Jan 2020 13:02:53 +0100 Message-ID: <20200130120253.GU24244@dhcp22.suse.cz> References: <1580334531-80354-1-git-send-email-yang.shi@linux.alibaba.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-api-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Vlastimil Babka Cc: Yang Shi , mtk.manpages-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org, akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org, linux-man-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-api@vger.kernel.org On Thu 30-01-20 10:06:28, Vlastimil Babka wrote: > On 1/29/20 10:48 PM, Yang Shi wrote: > > Since commit a49bd4d71637 ("mm, numa: rework do_pages_move"), > > the semantic of move_pages() has changed to return the number of > > non-migrated pages if they were result of a non-fatal reasons (usually a > > busy page). This was an unintentional change that hasn't been noticed > > except for LTP tests which checked for the documented behavior. > > > > There are two ways to go around this change. We can even get back to the > > original behavior and return -EAGAIN whenever migrate_pages is not able > > The manpage says EBUSY, not EAGAIN? And should its description be > updated too? The idea was that we _could_ return EAGAIN from the syscall if migrate_pages > 0. > I.e. that it's no longer returned since 4.17? I am pretty sure this will require a deeper consideration. Do we return EIO/EINVAL? -- Michal Hocko SUSE Labs