From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-it0-f72.google.com (mail-it0-f72.google.com [209.85.214.72]) by kanga.kvack.org (Postfix) with ESMTP id B5350280269 for ; Tue, 7 Nov 2017 10:55:49 -0500 (EST) Received: by mail-it0-f72.google.com with SMTP id r127so2622222itb.4 for ; Tue, 07 Nov 2017 07:55:49 -0800 (PST) Received: from resqmta-ch2-02v.sys.comcast.net (resqmta-ch2-02v.sys.comcast.net. [2001:558:fe21:29:69:252:207:34]) by mx.google.com with ESMTPS id p131si1604448itp.122.2017.11.07.07.55.48 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 07 Nov 2017 07:55:49 -0800 (PST) Date: Tue, 7 Nov 2017 09:55:47 -0600 (CST) From: Christopher Lameter Subject: Re: [PATCH RFC v2 4/4] mm/mempolicy: add nodes_empty check in SYSC_migrate_pages In-Reply-To: <04e4cb50-8cba-58af-1a5e-61e818cffa70@suse.cz> Message-ID: References: <1509099265-30868-1-git-send-email-xieyisheng1@huawei.com> <1509099265-30868-5-git-send-email-xieyisheng1@huawei.com> <04e4cb50-8cba-58af-1a5e-61e818cffa70@suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Sender: owner-linux-mm@kvack.org List-ID: To: Vlastimil Babka Cc: Yisheng Xie , akpm@linux-foundation.org, mhocko@suse.com, mingo@kernel.org, rientjes@google.com, n-horiguchi@ah.jp.nec.com, salls@cs.ucsb.edu, linux-mm@kvack.org, linux-kernel@vger.kernel.org, tanxiaojun@huawei.com, linux-api@vger.kernel.org, Andi Kleen On Tue, 7 Nov 2017, Vlastimil Babka wrote: > > Migrate pages moves the pages of a single process there is no TARGET > > process. > > migrate_pages(2) takes a pid argument > > "migrate_pages() attempts to move all pages of the process pid that > are in memory nodes old_nodes to the memory nodes in new_nodes. " Ok missed that. Most use cases here are on the current process. Fundamentally a process can have shared pages outside of the cpuset that a process is restricted to. Thus I would think that migration to any of the allowed nodes of the current process that is calling migrate pages is ok. The caller wants this and the caller has a right to allocate on these nodes. It would be strange if migrate_pages would allow allocation outside of the current cpuset. > > Thus thehe *target* nodes need to be a subset of the current cpu set. And therefore the above still holds. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org