From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0588E2459FD for ; Tue, 21 Oct 2025 04:10:24 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761019826; cv=none; b=tyIoaE6JKmc9MRtKXwpHSN7Qv8VeQekTtLN2Z4Rw/ZrBcb2otqgp6xMNpAeIMV7Y4+jgXVAN/gdMv2wV1OXpJjfAX2aSCFlyL3fLaWBAAcHeS1+2PBJmIadRijBsLP5KQ873XLmwStxK9WnscDZKhC2khUM+ilvFtxg7M1R3uj0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761019826; c=relaxed/simple; bh=m6Ygrj9CfSu9M6zL1BkSWa/FjgjlVS2hjqfbAo77jSE=; h=From:Message-ID:Date:MIME-Version:Subject:To:Cc:References: In-Reply-To:Content-Type; b=ndYf/M//XFwu58a4str5CsiYeTQhKUdqysg9wKFwUguH0chH/UPGzulMAXOE8lR3G+7PRBbF/3XrutahkBcxFeJiGVRroQ6uVUzJHghxAQPJ6ml7DC7NcYCEtWQxnwHu8rQyoqqYkczyICgiqhaM7J3itnuSd6n1/aIsW/aFYzg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=EFgCUByo; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="EFgCUByo" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1761019823; 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: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=r9OupL1guxMQZzERaZQ5HIFJ+HTh+MX5SgUIo3LTaUY=; b=EFgCUByoM4QfmSq0a5kM72QLaW+qAi03T14bhkOSK4dFQbUyfcSeVLyLdeRhTkRe7L3Nx1 T1Ch37UbLAp2JYx1a0JOUJ1hawISVoyLefHKSiwciYgWYKKCppkZqwHeEPouFcgGYB5w8P uBUQwBTq/+vYXhTkrK8upAhEEPP5SVw= Received: from mail-qv1-f69.google.com (mail-qv1-f69.google.com [209.85.219.69]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-436-zshew64UPfOrsFhgzepRpA-1; Tue, 21 Oct 2025 00:10:22 -0400 X-MC-Unique: zshew64UPfOrsFhgzepRpA-1 X-Mimecast-MFC-AGG-ID: zshew64UPfOrsFhgzepRpA_1761019822 Received: by mail-qv1-f69.google.com with SMTP id 6a1803df08f44-79a3c16b276so161214726d6.0 for ; Mon, 20 Oct 2025 21:10:22 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1761019822; x=1761624622; h=content-transfer-encoding:in-reply-to:content-language:references :cc:to:subject:user-agent:mime-version:date:message-id:from :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=r9OupL1guxMQZzERaZQ5HIFJ+HTh+MX5SgUIo3LTaUY=; b=Iu4hzsVlTJw1TvlETSfE+w4jPg3ItJ2un7J3pm5vcO3mhPFTC+gsjhAiWdEAciUh2L JrIdAVG5i4bzVuXzlueSjvEpHJdn+lOmPr/2Ev6TO6Axb035Gkch2hyN/kCd24UT5YCr r/WlPgitj9pm6aT9+pJ4X8OKZj1upI3LljZV+zCyxI6PTV6B10Z6xdCpHXKzWlzZf84w mfZB0ELvZTl1MOxPyMPwlIu3/GeqTl9v5xczpsh7aJHGrrRRSQe0BDBpZrikHlXetGHa jtLm53dq4oB7wZFd5ZLwNW2D/CPhfZzpgg4KzzRnkkAF/lZMdbeLYcoCNW4105fu1L1e u+hA== X-Forwarded-Encrypted: i=1; AJvYcCXlfyN5u9uXFRGjAwPgsz8cs1wfGgw8OWdMwDF5JDPinbn0pK/Fp9x5RxK58wM9UfLas0wUOxID3X/JAg==@vger.kernel.org X-Gm-Message-State: AOJu0Yz9KFGUP5PrrpxhVURHXf1p+OLyx4LVpjQK6IxB/8wDmyu6s0+/ lRYIWtqSgNpPzv5BBCVpjW30+bE9F+9DPG7A2gU0AOs1laz/H73vt4BMb+uMvshOf9N0eOQh1Oo L/ixvp8GPFPM8oBVhuxBxdzdwvLAHxt6NV6ao3fIl6LVajfEND2M1QK1zcrJRoLe9 X-Gm-Gg: ASbGncuK86ZxeCi30EdxmRD+P5QYziVvx0OOTLQaXzsqzk6PzUlXI984bVdf+sU2A3S +xh/HDRZgsNJFche6lAoGpIK4a2OWm+t2cpzjDTFP+t2CP1RByRd3em5I/uCu95b2yXLbRXRauI D0gzyxNMIqTLCasQD+JrqMZBLNY60YFrB0Vi3hTF7gJ1gWChtRIgbShVpbvZIPHmoqa2yxMEj3O FFizZvoCuOxtcWLE6wWlDtRoV5QqzI7jgRw2x4CRRsl/7ybJdE2KnaQ1qwBpmHuXS2pbNSH2n2i n3YMbVMXelUNYWXNiPubGnQehFQXdogn39ru8vFTl2eMnTjZsAxgDzmDVeB/fFgpZUZv3o/Y+mn xCYssDb0EdnARQ/7XvaqdW1YRMxSQK8ezKNFXDcmvBwJGhQ== X-Received: by 2002:a05:6214:808f:b0:87c:223c:c5c8 with SMTP id 6a1803df08f44-87c223cc6b8mr152673926d6.20.1761019821874; Mon, 20 Oct 2025 21:10:21 -0700 (PDT) X-Google-Smtp-Source: AGHT+IGdm2hwRLRcjdAJaN67gocvEQv/ytDjJvvxgQlCm7/W761K2ldQ2/8L5ftdru4g+9p/5t/b/A== X-Received: by 2002:a05:6214:808f:b0:87c:223c:c5c8 with SMTP id 6a1803df08f44-87c223cc6b8mr152673626d6.20.1761019821460; Mon, 20 Oct 2025 21:10:21 -0700 (PDT) Received: from ?IPV6:2601:600:947f:f020:85dc:d2b2:c5ee:e3c4? ([2601:600:947f:f020:85dc:d2b2:c5ee:e3c4]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-87d028af525sm62600596d6.51.2025.10.20.21.10.17 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 20 Oct 2025 21:10:20 -0700 (PDT) From: Waiman Long X-Google-Original-From: Waiman Long Message-ID: <0e02915f-bde7-4b04-b760-89f34fb0a436@redhat.com> Date: Tue, 21 Oct 2025 00:10:16 -0400 Precedence: bulk X-Mailing-List: linux-block@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 13/33] cpuset: Update HK_TYPE_DOMAIN cpumask from cpuset To: Frederic Weisbecker , LKML Cc: =?UTF-8?Q?Michal_Koutn=C3=BD?= , Andrew Morton , Bjorn Helgaas , Catalin Marinas , Danilo Krummrich , "David S . Miller" , Eric Dumazet , Gabriele Monaco , Greg Kroah-Hartman , Ingo Molnar , Jakub Kicinski , Jens Axboe , Johannes Weiner , Lai Jiangshan , Marco Crivellari , Michal Hocko , Muchun Song , Paolo Abeni , Peter Zijlstra , Phil Auld , "Rafael J . Wysocki" , Roman Gushchin , Shakeel Butt , Simon Horman , Tejun Heo , Thomas Gleixner , Vlastimil Babka , Will Deacon , cgroups@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-block@vger.kernel.org, linux-mm@kvack.org, linux-pci@vger.kernel.org, netdev@vger.kernel.org References: <20251013203146.10162-1-frederic@kernel.org> <20251013203146.10162-14-frederic@kernel.org> Content-Language: en-US In-Reply-To: <20251013203146.10162-14-frederic@kernel.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 10/13/25 4:31 PM, Frederic Weisbecker wrote: > Until now, HK_TYPE_DOMAIN used to only include boot defined isolated > CPUs passed through isolcpus= boot option. Users interested in also > knowing the runtime defined isolated CPUs through cpuset must use > different APIs: cpuset_cpu_is_isolated(), cpu_is_isolated(), etc... > > There are many drawbacks to that approach: > > 1) Most interested subsystems want to know about all isolated CPUs, not > just those defined on boot time. > > 2) cpuset_cpu_is_isolated() / cpu_is_isolated() are not synchronized with > concurrent cpuset changes. > > 3) Further cpuset modifications are not propagated to subsystems > > Solve 1) and 2) and centralize all isolated CPUs within the > HK_TYPE_DOMAIN housekeeping cpumask. > > Subsystems can rely on RCU to synchronize against concurrent changes. > > The propagation mentioned in 3) will be handled in further patches. > > Signed-off-by: Frederic Weisbecker > --- > include/linux/sched/isolation.h | 2 + > kernel/cgroup/cpuset.c | 2 + > kernel/sched/isolation.c | 75 ++++++++++++++++++++++++++++++--- > kernel/sched/sched.h | 1 + > 4 files changed, 74 insertions(+), 6 deletions(-) > > diff --git a/include/linux/sched/isolation.h b/include/linux/sched/isolation.h > index da22b038942a..94d5c835121b 100644 > --- a/include/linux/sched/isolation.h > +++ b/include/linux/sched/isolation.h > @@ -32,6 +32,7 @@ extern const struct cpumask *housekeeping_cpumask(enum hk_type type); > extern bool housekeeping_enabled(enum hk_type type); > extern void housekeeping_affine(struct task_struct *t, enum hk_type type); > extern bool housekeeping_test_cpu(int cpu, enum hk_type type); > +extern int housekeeping_update(struct cpumask *mask, enum hk_type type); > extern void __init housekeeping_init(void); > > #else > @@ -59,6 +60,7 @@ static inline bool housekeeping_test_cpu(int cpu, enum hk_type type) > return true; > } > > +static inline int housekeeping_update(struct cpumask *mask, enum hk_type type) { return 0; } > static inline void housekeeping_init(void) { } > #endif /* CONFIG_CPU_ISOLATION */ > > diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c > index aa1ac7bcf2ea..b04a4242f2fa 100644 > --- a/kernel/cgroup/cpuset.c > +++ b/kernel/cgroup/cpuset.c > @@ -1403,6 +1403,8 @@ static void update_unbound_workqueue_cpumask(bool isolcpus_updated) > > ret = workqueue_unbound_exclude_cpumask(isolated_cpus); > WARN_ON_ONCE(ret < 0); > + ret = housekeeping_update(isolated_cpus, HK_TYPE_DOMAIN); > + WARN_ON_ONCE(ret < 0); > } > > /** > diff --git a/kernel/sched/isolation.c b/kernel/sched/isolation.c > index b46c20b5437f..95d69c2102f6 100644 > --- a/kernel/sched/isolation.c > +++ b/kernel/sched/isolation.c > @@ -29,18 +29,48 @@ static struct housekeeping housekeeping; > > bool housekeeping_enabled(enum hk_type type) > { > - return !!(housekeeping.flags & BIT(type)); > + return !!(READ_ONCE(housekeeping.flags) & BIT(type)); > } > EXPORT_SYMBOL_GPL(housekeeping_enabled); > > +static bool housekeeping_dereference_check(enum hk_type type) > +{ > + if (IS_ENABLED(CONFIG_LOCKDEP) && type == HK_TYPE_DOMAIN) { > + /* Cpuset isn't even writable yet? */ > + if (system_state <= SYSTEM_SCHEDULING) > + return true; > + > + /* CPU hotplug write locked, so cpuset partition can't be overwritten */ > + if (IS_ENABLED(CONFIG_HOTPLUG_CPU) && lockdep_is_cpus_write_held()) > + return true; > + > + /* Cpuset lock held, partitions not writable */ > + if (IS_ENABLED(CONFIG_CPUSETS) && lockdep_is_cpuset_held()) > + return true; I have some doubt about this condition as the cpuset_mutex may be held in the process of making changes to an isolated partition that will impact HK_TYPE_DOMAIN cpumask. Cheers, Longman