From mboxrd@z Thu Jan 1 00:00:00 1970 From: ebiederm@xmission.com (Eric W. Biederman) Subject: Re: [PATCH] move_pages.2: not return ENOENT if the page are already on the target nodes Date: Mon, 30 Dec 2019 21:49:03 -0600 Message-ID: <87lfqtcfyo.fsf@x220.int.ebiederm.org> References: <1575596090-115377-1-git-send-email-yang.shi@linux.alibaba.com> <0dc96e40-5f2b-a2fe-6e5f-b6f3d5e9ebde@nvidia.com> <95170ea5-5b62-9168-fcd9-93b43330a1b4@linux.alibaba.com> <092adc11-7039-9343-7067-0e0199c9dc13@gmail.com> <51dd767a-221f-882d-c7f6-45bd0c217a67@nvidia.com> <20191218101711.GB21485@dhcp22.suse.cz> <0059a598-5726-2488-cd37-b4b7f9b3353e@linux.alibaba.com> Mime-Version: 1.0 Content-Type: text/plain Return-path: In-Reply-To: <0059a598-5726-2488-cd37-b4b7f9b3353e@linux.alibaba.com> (Yang Shi's message of "Mon, 30 Dec 2019 19:00:43 -0800") Sender: linux-kernel-owner@vger.kernel.org To: Yang Shi Cc: Michal Hocko , John Hubbard , "Michael Kerrisk (man-pages)" , cl@linux.com, cai@lca.pw, akpm@linux-foundation.org, linux-man@vger.kernel.org, linux-api@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org List-Id: linux-api@vger.kernel.org Yang Shi writes: > On 12/18/19 2:17 AM, Michal Hocko wrote: >> On Tue 17-12-19 23:36:09, John Hubbard wrote: >> [...] >>> diff --git a/man2/move_pages.2 b/man2/move_pages.2 >>> index 2d96468fa..1bf1053f2 100644 >>> --- a/man2/move_pages.2 >>> +++ b/man2/move_pages.2 >>> @@ -191,12 +191,6 @@ was specified or an attempt was made to migrate pages of a kernel thread. >>> .B ENODEV >>> One of the target nodes is not online. >>> .TP >>> -.B ENOENT >>> -No pages were found that require moving. >>> -All pages are either already >>> -on the target node, not present, had an invalid address or could not be >>> -moved because they were mapped by multiple processes. >>> -.TP >>> .B EPERM >>> The caller specified >>> .B MPOL_MF_MOVE_ALL >>> >>> ...But I'm not sure if we should change the implementation, instead, so >>> that it *can* return ENOENT. That's the main question to resolve before >>> creating any more patches, I think. >> I would start by dropping any note about ENOENT first. I am not really >> sure there is a reasonable usecase for it but maybe somebody comes up >> with something and only then we should consider it. >> >> Feel free to add >> Acked-by: Michal Hocko >> >> ideally with a kernel commit which removed the ENOENT. > > A quick audit doesn't show kernel code or comment notes about ENOENT > wrongly. The status could be set as ENOENT if the page is not present > (follow_page() returns NULL), and man page does match what kernel > does. Doesn't the function one layer up then consume the ENOENT? Eric