From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 1467C34DCEC; Wed, 5 Nov 2025 21:05:45 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762376745; cv=none; b=fDS9+oDIGi1fdHgZFZQ/lBX5O/LJepiznQEEIEAQzsDVl5kzfP0+8TutitObprPjH1D3LKmqniT0bo4O9nniwe/rNmymFhZ/0KLzb6pXx6CIVyxt+EMHMb3zY64KPzGxxb1YfYbphliXbsXsKtvYeiBg+OMR8RVT51VNjTL7fh0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762376745; c=relaxed/simple; bh=NSCbW1jqRDXNXOPN1q+JI6ONLqfc5mcXxsKSGojX9XI=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=ebfKXD88JsG5vrwfaA1WkRjGQiOVEXYTMBMZzTh1WjSLL9K2y0T7JGczBgCf+Ius4N26HR/K8i6ObdPvcFKnN7/dyiFk1f3XEp/Tlng8OP/lqir6mFF5/x+yb3+XqGErllUSgBeCRnog5Odc60W1dKYZHDlEVoA2IHmG37gNkDI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=LWMPtEAp; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="LWMPtEAp" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 58A86C116B1; Wed, 5 Nov 2025 21:05:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1762376744; bh=NSCbW1jqRDXNXOPN1q+JI6ONLqfc5mcXxsKSGojX9XI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=LWMPtEAp/SsLSnIk4m9A51hGP5hc8yyJBfe6xKhxmY+YrwzM32WL807kODsfESVMz fF20ZBdm8d/ym9V3Zmx4xpDAk9A6WPScqbcRTBISSmofkLCz3/o2qRSxceU3mk65Lb PMiOQVFgTZ/Ybf229Gsbmwo83ZPVdYeyNiPR7BNF5Sqw6xo4kNThz+82IRPGtzf1+C cKmE2pjXhT/2gMis1KSX4NCGdARFqBpIKATDnY37g1s7cOHae3a8oqWNQFjzCX5uj/ I3/SJvSHJ0AboZHGXpc9Bs80RhWWAN6f5aKr/xGZEGmmsNG1i/DG43cD41sYayUrc7 czbmTyBk5vpaQ== From: Frederic Weisbecker To: LKML Cc: Frederic Weisbecker , =?UTF-8?q?Michal=20Koutn=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 , Waiman Long , 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 Subject: [PATCH 13/31] cpuset: Update HK_TYPE_DOMAIN cpumask from cpuset Date: Wed, 5 Nov 2025 22:03:29 +0100 Message-ID: <20251105210348.35256-14-frederic@kernel.org> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20251105210348.35256-1-frederic@kernel.org> References: <20251105210348.35256-1-frederic@kernel.org> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 | 7 +++ kernel/cgroup/cpuset.c | 2 + kernel/sched/isolation.c | 76 ++++++++++++++++++++++++++++++--- kernel/sched/sched.h | 1 + 4 files changed, 80 insertions(+), 6 deletions(-) diff --git a/include/linux/sched/isolation.h b/include/linux/sched/isolation.h index 109a2149e21a..aaf2a672f8dc 100644 --- a/include/linux/sched/isolation.h +++ b/include/linux/sched/isolation.h @@ -9,6 +9,11 @@ enum hk_type { /* Revert of boot-time isolcpus= argument */ HK_TYPE_DOMAIN_BOOT, + /* + * Same as HK_TYPE_DOMAIN_BOOT but also includes the + * revert of cpuset isolated partitions. As such it + * is always a subset of HK_TYPE_DOMAIN_BOOT. + */ HK_TYPE_DOMAIN, /* Revert of boot-time isolcpus=managed_irq argument */ HK_TYPE_MANAGED_IRQ, @@ -35,6 +40,7 @@ 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 @@ -62,6 +68,7 @@ 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 bee6c04be103..80a5b7c6400c 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; + + return false; + } + + return true; +} + +static inline struct cpumask *housekeeping_cpumask_dereference(enum hk_type type) +{ + return rcu_dereference_all_check(housekeeping.cpumasks[type], + housekeeping_dereference_check(type)); +} + const struct cpumask *housekeeping_cpumask(enum hk_type type) { + const struct cpumask *mask = NULL; + if (static_branch_unlikely(&housekeeping_overridden)) { - if (housekeeping.flags & BIT(type)) { - return rcu_dereference_check(housekeeping.cpumasks[type], 1); - } + if (READ_ONCE(housekeeping.flags) & BIT(type)) + mask = housekeeping_cpumask_dereference(type); } - return cpu_possible_mask; + if (!mask) + mask = cpu_possible_mask; + return mask; } EXPORT_SYMBOL_GPL(housekeeping_cpumask); @@ -80,12 +110,46 @@ EXPORT_SYMBOL_GPL(housekeeping_affine); bool housekeeping_test_cpu(int cpu, enum hk_type type) { - if (static_branch_unlikely(&housekeeping_overridden) && housekeeping.flags & BIT(type)) + if (static_branch_unlikely(&housekeeping_overridden) && + READ_ONCE(housekeeping.flags) & BIT(type)) return cpumask_test_cpu(cpu, housekeeping_cpumask(type)); return true; } EXPORT_SYMBOL_GPL(housekeeping_test_cpu); +int housekeeping_update(struct cpumask *mask, enum hk_type type) +{ + struct cpumask *trial, *old = NULL; + + if (type != HK_TYPE_DOMAIN) + return -ENOTSUPP; + + trial = kmalloc(cpumask_size(), GFP_KERNEL); + if (!trial) + return -ENOMEM; + + cpumask_andnot(trial, housekeeping_cpumask(HK_TYPE_DOMAIN_BOOT), mask); + if (!cpumask_intersects(trial, cpu_online_mask)) { + kfree(trial); + return -EINVAL; + } + + if (!housekeeping.flags) + static_branch_enable(&housekeeping_overridden); + + if (housekeeping.flags & BIT(type)) + old = housekeeping_cpumask_dereference(type); + else + WRITE_ONCE(housekeeping.flags, housekeeping.flags | BIT(type)); + rcu_assign_pointer(housekeeping.cpumasks[type], trial); + + synchronize_rcu(); + + kfree(old); + + return 0; +} + void __init housekeeping_init(void) { enum hk_type type; diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index 2fc1ddde3120..5a44e85d4864 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -30,6 +30,7 @@ #include #include #include +#include #include #include #include -- 2.51.0