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 467DBC2BA4C for ; Wed, 26 Jan 2022 07:30:36 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id A2D4A6B0071; Wed, 26 Jan 2022 02:30:35 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 9DDA26B0074; Wed, 26 Jan 2022 02:30:35 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 8CBA76B0075; Wed, 26 Jan 2022 02:30:35 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0227.hostedemail.com [216.40.44.227]) by kanga.kvack.org (Postfix) with ESMTP id 7DDF16B0071 for ; Wed, 26 Jan 2022 02:30:35 -0500 (EST) Received: from smtpin12.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id 3247518495710 for ; Wed, 26 Jan 2022 07:30:35 +0000 (UTC) X-FDA: 79071615630.12.D45917E Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) by imf18.hostedemail.com (Postfix) with ESMTP id AE0AA1C0002 for ; Wed, 26 Jan 2022 07:30:29 +0000 (UTC) Date: Wed, 26 Jan 2022 08:30:26 +0100 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1643182228; h=from:from:reply-to:subject:subject: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=9NZ3lJVnTo7mLG1upjj5vlqJmvStFoul39zOV2ksyiw=; b=YdF40EP8NbbaYR4CLObHjD/v1L3OyjJSpWu7WzHz2yclKAch8LWLxg6o1leUYjkVM4JwZR tfZNk4cgFU0TAlLhbJ0V9CmXx9TCxzi9xy0MhYPR+qJUP7zQLnvYgxric+KmJN2I06cXok NMTFJq3ypCS/P3dLap9wGu8Y4B6m5ogPtuzt99+zU3ILJ3UQJMZqRrEPrEqReyxpaf3QER JbUjrUW1vowb7PoT0GITodpBrtfHilSj8QFjd++QbsrWwhtJN6FdWmz9RRYvyufZWkQghi TvmGsQX/4/hl0ADe6yM248PvCvXRlwQzGopXMgpA5OmC+5oeMq4bdbBPK/06eg== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1643182228; h=from:from:reply-to:subject:subject: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=9NZ3lJVnTo7mLG1upjj5vlqJmvStFoul39zOV2ksyiw=; b=W2T8DfnRpP/yM/quFoYVhVRZ0BnYogZZrluWaWuREyW1CnGUo2yehjAouXi5rt3hDPe9et X09WVcHB0qlhPuBA== From: Sebastian Andrzej Siewior To: Andrew Morton Cc: cgroups@vger.kernel.org, linux-mm@kvack.org, Johannes Weiner , Michal Hocko , Michal =?utf-8?Q?Koutn=C3=BD?= , Peter Zijlstra , Thomas Gleixner , Vladimir Davydov , Waiman Long Subject: Re: [PATCH 0/4] mm/memcg: Address PREEMPT_RT problems instead of disabling it. Message-ID: References: <20220125164337.2071854-1-bigeasy@linutronix.de> <20220125152146.d7e25afe3b8a6807df6fee3f@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20220125152146.d7e25afe3b8a6807df6fee3f@linux-foundation.org> X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: AE0AA1C0002 X-Stat-Signature: 3j44u11mz6wbt1d1oi8fehawnyd8tm9d Authentication-Results: imf18.hostedemail.com; dkim=pass header.d=linutronix.de header.s=2020 header.b=YdF40EP8; dkim=pass header.d=linutronix.de header.s=2020e header.b=W2T8DfnR; dmarc=pass (policy=none) header.from=linutronix.de; spf=pass (imf18.hostedemail.com: domain of bigeasy@linutronix.de designates 193.142.43.55 as permitted sender) smtp.mailfrom=bigeasy@linutronix.de X-Rspam-User: nil X-HE-Tag: 1643182229-523983 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000016, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 2022-01-25 15:21:46 [-0800], Andrew Morton wrote: > On Tue, 25 Jan 2022 17:43:33 +0100 Sebastian Andrzej Siewior wrote: > > > Hi, > > > > this series is a follow up to the initial RFC > > https://lore.kernel.org/all/20211222114111.2206248-1-bigeasy@linutronix.de > > > > and aims to enable MEMCG for PREEMPT_RT instead of disabling it. > > > > where it has been suggested that I should try again with memcg instead > > of simply disabling it. > > > > Changes since the RFC: > > - cgroup.event_control / memory.soft_limit_in_bytes is disabled on > > PREEMPT_RT. It is a deprecated v1 feature. Fixing the signal path is > > not worth it. > > > > - The updates to per-CPU counters are usually synchronised by disabling > > interrupts. There are a few spots where assumption about disabled > > interrupts are not true on PREEMPT_RT and therefore preemption is > > disabled. This is okay since the counter are never written from > > in_irq() context. > > > > Patch #2 deals with the counters. > > > > Patch #3 is a follow up to > > https://lkml.kernel.org/r/20211214144412.447035-1-longman@redhat.com > > > > Patch #4 restricts the task_obj usage to !PREEMPTION kernels. Based on > > the numbers in > > https://lore.kernel.org/all/YdX+INO9gQje6d0S@linutronix.de > > This isn't a terribly useful [0/n], sorry. It would be better to have > something self-contained which doesn't require that the reader chase > down increasingly old links and figure out what changed during > successive iterations. I'm sorry. I didn't want to copy the numbers and make the impression of doing the numbers now on -rc1. > > I tested them on CONFIG_PREEMPT_NONE + CONFIG_PREEMPT_RT with the > > tools/testing/selftests/cgroup/* tests. It looked good except for the > > following (which was also there before the patches): > > - test_kmem sometimes complained about: > > not ok 2 test_kmem_memcg_deletion > > Is this a new issue? No, I saw it already on 5.16.0-rc5. > Does this happen with these patches when CONFIG_PREEMPT_RT=n? Yes. The problem reported by the test is independent of the series and RT. > > - test_memcontrol complained always about > > not ok 3 test_memcg_min > > not ok 4 test_memcg_low > > and did not finish. > > Similarly, is this caused by these patches? Is it only triggered under > preempt_rt? No. This happens regardless of these patches and RT. > > - lockdep complains were triggered by test_core and test_freezer (both > > had to run): > > Ditto. Also happens regardless of these patches and RT. It does not happen always so sometimes I had to run test_core and test_freezer a few times until lockdep complained. Sebastian