From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christopher Lameter Subject: Re: [PATCH RFC v2 4/4] mm/mempolicy: add nodes_empty check in SYSC_migrate_pages Date: Mon, 6 Nov 2017 09:29:49 -0600 (CST) Message-ID: References: <1509099265-30868-1-git-send-email-xieyisheng1@huawei.com> <1509099265-30868-5-git-send-email-xieyisheng1@huawei.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Return-path: In-Reply-To: Sender: linux-api-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Vlastimil Babka Cc: Yisheng Xie , akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org, mhocko-IBi9RG/b67k@public.gmane.org, mingo-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, rientjes-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org, n-horiguchi-PaJj6Psr51x8UrSeD/g0lQ@public.gmane.org, salls-b3bnyZ7c9ISVc3sceRu5cw@public.gmane.org, linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, tanxiaojun-hv44wF8Li93QT0dZR+AlfA@public.gmane.org, linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Andi Kleen List-Id: linux-api@vger.kernel.org On Mon, 6 Nov 2017, Vlastimil Babka wrote: > I'm not sure what exactly is the EPERM intention. Should really the > capability of THIS process override the cpuset restriction of the TARGET > process? Maybe yes. Then, does "insufficient privilege (CAP_SYS_NICE) to CAP_SYS_NICE never overrides cpuset restrictions. The cap can be used to migrate pages that are *also* mapped by other processes (and thus move pages of another process which may have different cpu set restrictions!). The cap should not allow migrating pages to nodes that are not allowed by the cpuset of the current process.