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 D3917C433F5 for ; Mon, 13 Dec 2021 10:08:53 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 54F2B6B0071; Mon, 13 Dec 2021 05:08:43 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 4FF0E6B0073; Mon, 13 Dec 2021 05:08:43 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 3C6B16B0074; Mon, 13 Dec 2021 05:08:43 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0021.hostedemail.com [216.40.44.21]) by kanga.kvack.org (Postfix) with ESMTP id 29B996B0071 for ; Mon, 13 Dec 2021 05:08:43 -0500 (EST) Received: from smtpin21.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id E14C58249980 for ; Mon, 13 Dec 2021 10:08:32 +0000 (UTC) X-FDA: 78912346506.21.66EBDF8 Received: from smtp-out1.suse.de (smtp-out1.suse.de [195.135.220.28]) by imf08.hostedemail.com (Postfix) with ESMTP id 56486160014 for ; Mon, 13 Dec 2021 10:08:27 +0000 (UTC) Received: from relay2.suse.de (relay2.suse.de [149.44.160.134]) by smtp-out1.suse.de (Postfix) with ESMTP id E7F6E2111A; Mon, 13 Dec 2021 10:08:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1639390108; 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=sAlFWeBlMiXf+1RQBWZpSz97qKdbH168dZaJ4vBCj88=; b=rUPcmILWZKV8HVQCcAOG/7r1sDRrpwu3h02jFJQISqeJswZm+cmuKuPjTJzDAdK+xGFhdg OnM0Cae/CVt5zFQbjxQRDYh5WCHEo8C3zHEBNwB06Srz3YgrlHTotzrr02Zu1pi4Chq8Tq 9WdcpaC89KsMkxK4es9O0AwrnBXd3NE= Received: from suse.cz (unknown [10.100.201.86]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by relay2.suse.de (Postfix) with ESMTPS id B620BA3B89; Mon, 13 Dec 2021 10:08:28 +0000 (UTC) Date: Mon, 13 Dec 2021 11:08:26 +0100 From: Michal Hocko To: Sebastian Andrzej Siewior Cc: Johannes Weiner , cgroups@vger.kernel.org, linux-mm@kvack.org, Andrew Morton , Thomas Gleixner , Vladimir Davydov , Waiman Long Subject: Re: [PATCH] mm/memcontrol: Disable on PREEMPT_RT Message-ID: References: <20211207155208.eyre5svucpg7krxe@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 56486160014 X-Stat-Signature: 4qmscmyudo4pazhe81cnfaomfmpinh13 Authentication-Results: imf08.hostedemail.com; dkim=pass header.d=suse.com header.s=susede1 header.b=rUPcmILW; spf=pass (imf08.hostedemail.com: domain of mhocko@suse.com designates 195.135.220.28 as permitted sender) smtp.mailfrom=mhocko@suse.com; dmarc=pass (policy=quarantine) header.from=suse.com X-HE-Tag: 1639390107-648887 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 Fri 10-12-21 16:22:01, Sebastian Andrzej Siewior wrote: [...] I am sorry but I didn't get to read and digest the rest of the message yet. Let me just point out this > The problematic part here is mem_cgroup_tree_per_node::lock which can > not be acquired with disabled interrupts on PREEMPT_RT. The "locking > scope" is not always clear to me. Also, if it is _just_ the counter, > then we might solve this differently. I do not think you should be losing sleep over soft limit reclaim. This is certainly not something to be used for RT workloads and rather than touching that code I think it makes some sense to simply disallow soft limit with RT enabled (i.e. do not allow to set any soft limit). -- Michal Hocko SUSE Labs