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 X-Spam-Level: X-Spam-Status: No, score=-4.0 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 937E7C433DF for ; Thu, 13 Aug 2020 11:15:09 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 5DDC821744 for ; Thu, 13 Aug 2020 11:15:09 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5DDC821744 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id E3BDF6B0005; Thu, 13 Aug 2020 07:15:08 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id DEBAB6B0006; Thu, 13 Aug 2020 07:15:08 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id D01CB6B0007; Thu, 13 Aug 2020 07:15:08 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0189.hostedemail.com [216.40.44.189]) by kanga.kvack.org (Postfix) with ESMTP id BA4FF6B0005 for ; Thu, 13 Aug 2020 07:15:08 -0400 (EDT) Received: from smtpin08.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id 7342082499A8 for ; Thu, 13 Aug 2020 11:15:08 +0000 (UTC) X-FDA: 77145288696.08.fog56_351381026ff3 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin08.hostedemail.com (Postfix) with ESMTP id 47AB01819E793 for ; Thu, 13 Aug 2020 11:15:08 +0000 (UTC) X-HE-Tag: fog56_351381026ff3 X-Filterd-Recvd-Size: 2278 Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) by imf29.hostedemail.com (Postfix) with ESMTP for ; Thu, 13 Aug 2020 11:15:07 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id C4035B700; Thu, 13 Aug 2020 11:15:28 +0000 (UTC) Date: Thu, 13 Aug 2020 13:15:05 +0200 From: Michal Hocko To: Uladzislau Rezki Cc: Thomas Gleixner , paulmck@kernel.org, LKML , RCU , linux-mm@kvack.org, Andrew Morton , Vlastimil Babka , Matthew Wilcox , "Theodore Y . Ts'o" , Joel Fernandes , Sebastian Andrzej Siewior , Oleksiy Avramchenko Subject: Re: [RFC-PATCH 1/2] mm: Add __GFP_NO_LOCKS flag Message-ID: <20200813111505.GG9477@dhcp22.suse.cz> References: <20200811210931.GZ4295@paulmck-ThinkPad-P72> <874kp87mca.fsf@nanos.tec.linutronix.de> <20200813075027.GD9477@dhcp22.suse.cz> <20200813095840.GA25268@pc636> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200813095840.GA25268@pc636> X-Rspamd-Queue-Id: 47AB01819E793 X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam02 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 Thu 13-08-20 11:58:40, Uladzislau Rezki wrote: [...] > Sorry for jumping in. We can rely on preemptable() for sure, if CONFIG_PREEMPT_RT > is enabled, something like below: > > if (IS_ENABLED_RT && preemptebale()) Sure. I thought this was an RT specific thing that would be noop otherwise. > Also i have a question about pcp-lists. Can we introduce and use all allowed > MIGRATE_PCPTYPES? If called with GFP_RT_SAFE? If not please elaborate. Yes we can. This depends on the provided gfp_mask. Many gfp flags will be meaningless for such a context but essentially all we care about is that ((gfp_mask & __GFP_RECLAIM) == GFP_RT_SAFE) for the checking purpose. We can sort out all these details if this is decided to be the right way to do. My (pseudo) patch was mostly to show the direction I've had in mind for easier further discussion. -- Michal Hocko SUSE Labs