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 6E7713277B4; Fri, 29 Aug 2025 15:49:00 +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=1756482540; cv=none; b=cxwzyhB0h5Omd7FVMcL6+07AzqX5shrD456UxZZ2/SJURmpmKb9eNoGDCGhcwgmqwThAt2W9LyDHOJgms4LRV9oVkRfTFAcjsL3hIemK8t8A2P6KAX7I0fZTw/AbXJxLWRfruEX7RFHFyFJbcUYFidFf9/fXaz0dySJSazqOrmY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756482540; c=relaxed/simple; bh=g05kmaCWh9kz1yQbOgKAwo02zbhbBJem0FHbC3D9l4A=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=SQUvZqwSSnd9c1XDiyGRKFag9m8H3NXFAiYqQxZyXFuOTJgjSaE76aA6d3N7DCQmfoOTRdo39sJnkHrS6pPMgj4zVAFnY8+BIHChaXR7Wi+clqSsJcU6qSl4Tb3npO+phdhNxzkat5gC6j4hL1enl2EGWj5szzNIwVYqPFToKKU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=NGTUIbf4; 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="NGTUIbf4" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3C553C4CEF6; Fri, 29 Aug 2025 15:48:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1756482539; bh=g05kmaCWh9kz1yQbOgKAwo02zbhbBJem0FHbC3D9l4A=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=NGTUIbf4zz1cc1V5OW0z+uuFGmmh71QLrS0tzI72BsW6ksimZ6s8fGz4XRCyjZVHO Ud9N+Ls6gp6mfjeQ5d2NXR9Rv+DO2EbERvrRVJ/O44hHoUm2x8XZ9ECWeN39YhbH/p 3gXeWAqmogFmZ52hpwv0j0AfOsXgIimnCQYKGDr5FP8YPHUcHWiTjFJEcOMY6iombU b+nsu7vYxOwRR2w3yzk4BNwfzFLxvIn2dbMZWQojn3JNfo3yhF6NMeNhOZFTMIt+8L rYGNTP/lC8zZ2tkJDnludtyxiDmn2VZHO8afTThalTdifySD47ISQ6usdbtUfPwji1 Xdqnul7SAbJnA== From: Frederic Weisbecker To: LKML Cc: Frederic Weisbecker , =?UTF-8?q?Michal=20Koutn=C3=BD?= , Ingo Molnar , Johannes Weiner , Marco Crivellari , Michal Hocko , Peter Zijlstra , Tejun Heo , Thomas Gleixner , Vlastimil Babka , Waiman Long , cgroups@vger.kernel.org Subject: [PATCH 14/33] cpuset: Update HK_TYPE_DOMAIN cpumask from cpuset Date: Fri, 29 Aug 2025 17:47:55 +0200 Message-ID: <20250829154814.47015-15-frederic@kernel.org> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20250829154814.47015-1-frederic@kernel.org> References: <20250829154814.47015-1-frederic@kernel.org> Precedence: bulk X-Mailing-List: cgroups@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 | 4 +- kernel/cgroup/cpuset.c | 2 + kernel/sched/isolation.c | 65 ++++++++++++++++++++++++++++++--- kernel/sched/sched.h | 1 + 4 files changed, 65 insertions(+), 7 deletions(-) diff --git a/include/linux/sched/isolation.h b/include/linux/sched/isolation.h index 9262378760b1..199d0fc4646f 100644 --- a/include/linux/sched/isolation.h +++ b/include/linux/sched/isolation.h @@ -36,12 +36,13 @@ extern bool housekeeping_test_cpu(int cpu, enum hk_type type); static inline bool housekeeping_cpu(int cpu, enum hk_type type) { - if (housekeeping_flags & BIT(type)) + if (READ_ONCE(housekeeping_flags) & BIT(type)) return housekeeping_test_cpu(cpu, type); else return true; } +extern int housekeeping_update(struct cpumask *mask, enum hk_type type); extern void __init housekeeping_init(void); #else @@ -74,6 +75,7 @@ static inline bool housekeeping_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 2d2fc74bc00c..4f2bc68332a7 100644 --- a/kernel/cgroup/cpuset.c +++ b/kernel/cgroup/cpuset.c @@ -1351,6 +1351,8 @@ 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 5ddb8dc5ca91..48f3b6b20604 100644 --- a/kernel/sched/isolation.c +++ b/kernel/sched/isolation.c @@ -23,16 +23,39 @@ EXPORT_SYMBOL_GPL(housekeeping_flags); 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 (type == HK_TYPE_DOMAIN) { + if (IS_ENABLED(CONFIG_HOTPLUG_CPU) && lockdep_is_cpus_write_held()) + return true; + if (IS_ENABLED(CONFIG_CPUSETS) && lockdep_is_cpuset_held()) + return true; + + return false; + } + + return true; +} + +static inline struct cpumask *__housekeeping_cpumask(enum hk_type type) +{ + return rcu_dereference_check(housekeeping_cpumasks[type], + housekeeping_dereference_check(type)); +} + const struct cpumask *housekeeping_cpumask(enum hk_type type) { - if (housekeeping_flags & BIT(type)) { - return rcu_dereference_check(housekeeping_cpumasks[type], 1); - } - return cpu_possible_mask; + const struct cpumask *mask = NULL; + + if (READ_ONCE(housekeeping_flags) & BIT(type)) + mask = __housekeeping_cpumask(type); + if (!mask) + mask = cpu_possible_mask; + return mask; } EXPORT_SYMBOL_GPL(housekeeping_cpumask); @@ -70,12 +93,42 @@ EXPORT_SYMBOL_GPL(housekeeping_affine); bool housekeeping_test_cpu(int cpu, enum hk_type type) { - if (housekeeping_flags & BIT(type)) + if (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(sizeof(*trial), 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 & BIT(type)) + old = __housekeeping_cpumask(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 0b1a233dcabf..d3512138027b 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