From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9A63AC4332F for ; Wed, 16 Nov 2022 09:44:18 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 1EF9C6B0071; Wed, 16 Nov 2022 04:44:18 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 19FB46B0072; Wed, 16 Nov 2022 04:44:18 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 0677C6B0073; Wed, 16 Nov 2022 04:44:18 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id EC2AD6B0071 for ; Wed, 16 Nov 2022 04:44:17 -0500 (EST) Received: from smtpin01.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay05.hostedemail.com (Postfix) with ESMTP id A6526410D7 for ; Wed, 16 Nov 2022 09:44:17 +0000 (UTC) X-FDA: 80138819754.01.E1EA654 Received: from smtp-out2.suse.de (smtp-out2.suse.de [195.135.220.29]) by imf06.hostedemail.com (Postfix) with ESMTP id 28E15180003 for ; Wed, 16 Nov 2022 09:44:16 +0000 (UTC) Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by smtp-out2.suse.de (Postfix) with ESMTPS id CB0651F917; Wed, 16 Nov 2022 09:44:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1668591855; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=bd1ed+hXkn5V0KAbqZOvNVfy2rS7WvVz5GEqvktKWWY=; b=X7MK3qsoKxTEpjWbFjE9xW0c2iyyPdjK7wws/FefVvJvW9CRT/hoRursX3YRl3h4gO/gln iWUy8RzwaPACPNE7Ka4m9J+lAieH4Z+Neuln6AnJPVivUFAoDvbEiBDBEAyHDtuKPtStIR VyMepZxN93/ysm6GILFefm67khV6+mU= Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id AAFE3134CE; Wed, 16 Nov 2022 09:44:15 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id V5FhJ++wdGNKPQAAMHmgww (envelope-from ); Wed, 16 Nov 2022 09:44:15 +0000 Date: Wed, 16 Nov 2022 10:44:15 +0100 From: Michal Hocko To: Zhongkun He Cc: "Huang, Ying" , corbet@lwn.net, akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-api@vger.kernel.org, linux-doc@vger.kernel.org Subject: Re: [External] Re: [PATCH v2] mm: add new syscall pidfd_set_mempolicy(). Message-ID: References: <20221111084051.2121029-1-hezhongkun.hzk@bytedance.com> <87zgcrwfac.fsf@yhuang6-desk2.ccr.corp.intel.com> <0445de39-15a4-f645-b380-39f20abb6524@bytedance.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <0445de39-15a4-f645-b380-39f20abb6524@bytedance.com> ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1668591857; a=rsa-sha256; cv=none; b=224DFCsGudCeo3Jn1+TOlRZgOtPl31N+b2bolvlg79Fmn4PP68hWD5OOkyIi5FqRFltSO2 TF88+W99SmdGApJKihj6w6jhbIIjyQmxpsvHOfArWYcGYv4Htcno6UZrUvpbvCpQgZu71H y0Pd2gaSpUiJhie0MEhPtUgxizUxu+c= ARC-Authentication-Results: i=1; imf06.hostedemail.com; dkim=pass header.d=suse.com header.s=susede1 header.b=X7MK3qso; spf=pass (imf06.hostedemail.com: domain of mhocko@suse.com designates 195.135.220.29 as permitted sender) smtp.mailfrom=mhocko@suse.com; dmarc=pass (policy=quarantine) header.from=suse.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1668591857; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=bd1ed+hXkn5V0KAbqZOvNVfy2rS7WvVz5GEqvktKWWY=; b=BOxJl6CKsdYHz09ctnriE8xMhx8+o+mUoD2OqRuI8Zc8rURSV71QxEMZ6sQJVrKQZqT+em /ErxWJGno8HGXx2V9T7zlX5BOjkj8l8rVnJtJwQYH6WEYgcztkmEt7ejXhb408olQ3OQi2 WhcqCxATrcGL5OoUoOWJnrKY0LeINGA= X-Stat-Signature: 49jgjozp7f8udbcky69d77i3yx6wz165 X-Rspamd-Queue-Id: 28E15180003 Authentication-Results: imf06.hostedemail.com; dkim=pass header.d=suse.com header.s=susede1 header.b=X7MK3qso; spf=pass (imf06.hostedemail.com: domain of mhocko@suse.com designates 195.135.220.29 as permitted sender) smtp.mailfrom=mhocko@suse.com; dmarc=pass (policy=quarantine) header.from=suse.com X-Rspamd-Server: rspam04 X-Rspam-User: X-HE-Tag: 1668591856-601485 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Wed 16-11-22 17:38:09, Zhongkun He wrote: > Hi Ying, thanks for your replay and suggestions. > > > > > I suggest to move the flags in "mode" parameter (MPOL_F_STATIC_NODES, > > MPOL_F_RELATIVE_NODES, MPOL_F_NUMA_BALANCING, etc.) to "flags" > > parameter, otherwise, why add it? > > The "flags" is used for future extension if any, just like > process_madvise() and set_mempolicy_home_node(). > Maybe it should be removed. No, please! Even if there is no use for the flags now we are usually terrible at predicting future and potential extensions. MPOL_F* is kinda flags but for historical reasons it is a separate mode and we shouldn't create a new confusion when this is treated differently for pidfd based APIs. > > And, how about add a "home_node" parameter? I don't think that it's a > > good idea to add another new syscall for pidfd_set_mempolicy_home_node() > > in the future. Why would this be a bad idea? > Good idea, but "home_node" is used for vma policy, not task policy. > It is possible to use it in pidfd_mbind() in the future. I woould go with pidfd_set_mempolicy_home_node to counterpart an existing syscall. -- Michal Hocko SUSE Labs