From nobody Sun Feb 8 11:43:14 2026 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 7E88C30F806; Sun, 25 Jan 2026 22:47:46 +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=1769381266; cv=none; b=GlbvfUrDLtpOLdUMtQe/xTvQqVnv2BvP0SJdS7ZcVL0IgGYG0S52z/2O+rI6F6Fpg7BW0OFwH6DmJRauKslWQjYUpHkB8EF1z0zz+b/YPnJrTHl+amjqQ4XV2mxq9cCrjCpmoopCE6zNrXTAsCi7k4BeS22uwnHwXzWKx4V6VTo= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769381266; c=relaxed/simple; bh=Qqaq4aoHo6a9PFuRdP+ZSEkR7bC/Dwwr9j36rrRCXWA=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=XN5sROl08CkNGtuI9Jctp76/n+JaptuPVlhEUZMoyRvCCEVz58Nnsh0PpEFX5CUQgz2WvDPfiivumvd5uP/BocvdFH2v/jAcO77oB+MxMCclpt+Vc9Dqi/yo+SMY/PFJBQHUrca+xx9xtUprpcBr5+xkPsVpH4bUMA1wXbLvjIo= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=VFdZRXOu; 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="VFdZRXOu" Received: by smtp.kernel.org (Postfix) with ESMTPSA id DEEFFC4CEF1; Sun, 25 Jan 2026 22:47:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1769381266; bh=Qqaq4aoHo6a9PFuRdP+ZSEkR7bC/Dwwr9j36rrRCXWA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=VFdZRXOuNskCqzkyJTn9woxy8lPuAJFb1axhe5T+7oO0PrH9tmfL11t1II0sm4SiO w5kUjkol7puwqNVbEmhXa26wvAAIi5Wvm4VYVF4ABPSjoCdfU6hGPkETjQQABXdKnk 7xkvXnpEFm0t/VtWXyVrWNtEIE29ZAWNjDNhh4zBpDIIe22sNVyjbFTTBJtjbYKBZk aXt+8mBfwP/0eTEeFGuyIhW3aSIK0wepa7mPCpWka8aDMUZEkFU+csINUz3q0/URFN N6KnuMomNJJbveTeQQADosEjw+jau46beFuYAV/XBbzpvDrwxhLUcP+zjVJq85SxXr Is+LWJ4pH0Hpw== From: Frederic Weisbecker To: LKML Cc: Frederic Weisbecker , =?UTF-8?q?Michal=20Koutn=C3=BD?= , Andrew Morton , Bjorn Helgaas , Catalin Marinas , Chen Ridong , 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 14/33] cpuset: Update HK_TYPE_DOMAIN cpumask from cpuset Date: Sun, 25 Jan 2026 23:45:21 +0100 Message-ID: <20260125224541.50226-15-frederic@kernel.org> X-Mailer: git-send-email 2.51.1 In-Reply-To: <20260125224541.50226-1-frederic@kernel.org> References: <20260125224541.50226-1-frederic@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Until now, HK_TYPE_DOMAIN used to only include boot defined isolated CPUs passed through isolcpus=3D 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. [Chen Ridong: Fix cpu_hotplug_lock deadlock and use correct static branch API] Signed-off-by: Frederic Weisbecker Reviewed-by: Waiman Long Reviewed-by: Chen Ridong Signed-off-by: Chen Ridong --- include/linux/sched/isolation.h | 7 +++ kernel/cgroup/cpuset.c | 5 ++- kernel/sched/isolation.c | 75 ++++++++++++++++++++++++++++++--- kernel/sched/sched.h | 1 + 4 files changed, 80 insertions(+), 8 deletions(-) diff --git a/include/linux/sched/isolation.h b/include/linux/sched/isolatio= n.h index c7cf6934489c..d8d9baf44516 100644 --- a/include/linux/sched/isolation.h +++ b/include/linux/sched/isolation.h @@ -9,6 +9,11 @@ enum hk_type { /* Inverse of boot-time isolcpus=3D argument */ HK_TYPE_DOMAIN_BOOT, + /* + * Same as HK_TYPE_DOMAIN_BOOT but also includes the + * inverse of cpuset isolated partitions. As such it + * is always a subset of HK_TYPE_DOMAIN_BOOT. + */ HK_TYPE_DOMAIN, /* Inverse of boot-time isolcpus=3Dmanaged_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 *isol_mask); extern void __init housekeeping_init(void); =20 #else @@ -62,6 +68,7 @@ static inline bool housekeeping_test_cpu(int cpu, enum hk= _type type) return true; } =20 +static inline int housekeeping_update(struct cpumask *isol_mask) { return = 0; } static inline void housekeeping_init(void) { } #endif /* CONFIG_CPU_ISOLATION */ =20 diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c index 5e2e3514c22e..e146e1f34bf9 100644 --- a/kernel/cgroup/cpuset.c +++ b/kernel/cgroup/cpuset.c @@ -1482,14 +1482,15 @@ static void update_isolation_cpumasks(void) if (!isolated_cpus_updating) return; =20 - lockdep_assert_cpus_held(); - ret =3D workqueue_unbound_exclude_cpumask(isolated_cpus); WARN_ON_ONCE(ret < 0); =20 ret =3D tmigr_isolated_exclude_cpumask(isolated_cpus); WARN_ON_ONCE(ret < 0); =20 + ret =3D housekeeping_update(isolated_cpus); + WARN_ON_ONCE(ret < 0); + isolated_cpus_updating =3D false; } =20 diff --git a/kernel/sched/isolation.c b/kernel/sched/isolation.c index 6f77289c14c3..674a02891b38 100644 --- a/kernel/sched/isolation.c +++ b/kernel/sched/isolation.c @@ -29,18 +29,48 @@ static struct housekeeping housekeeping; =20 bool housekeeping_enabled(enum hk_type type) { - return !!(housekeeping.flags & BIT(type)); + return !!(READ_ONCE(housekeeping.flags) & BIT(type)); } EXPORT_SYMBOL_GPL(housekeeping_enabled); =20 +static bool housekeeping_dereference_check(enum hk_type type) +{ + if (IS_ENABLED(CONFIG_LOCKDEP) && type =3D=3D HK_TYPE_DOMAIN) { + /* Cpuset isn't even writable yet? */ + if (system_state <=3D 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_typ= e 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 =3D 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 =3D housekeeping_cpumask_dereference(type); } - return cpu_possible_mask; + if (!mask) + mask =3D cpu_possible_mask; + return mask; } EXPORT_SYMBOL_GPL(housekeeping_cpumask); =20 @@ -80,12 +110,45 @@ EXPORT_SYMBOL_GPL(housekeeping_affine); =20 bool housekeeping_test_cpu(int cpu, enum hk_type type) { - if (static_branch_unlikely(&housekeeping_overridden) && housekeeping.flag= s & 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); =20 +int housekeeping_update(struct cpumask *isol_mask) +{ + struct cpumask *trial, *old =3D NULL; + + lockdep_assert_cpus_held(); + + trial =3D kmalloc(cpumask_size(), GFP_KERNEL); + if (!trial) + return -ENOMEM; + + cpumask_andnot(trial, housekeeping_cpumask(HK_TYPE_DOMAIN_BOOT), isol_mas= k); + if (!cpumask_intersects(trial, cpu_online_mask)) { + kfree(trial); + return -EINVAL; + } + + if (!housekeeping.flags) + static_branch_enable_cpuslocked(&housekeeping_overridden); + + if (housekeeping.flags & HK_FLAG_DOMAIN) + old =3D housekeeping_cpumask_dereference(HK_TYPE_DOMAIN); + else + WRITE_ONCE(housekeeping.flags, housekeeping.flags | HK_FLAG_DOMAIN); + rcu_assign_pointer(housekeeping.cpumasks[HK_TYPE_DOMAIN], 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 475bdab3b8db..653e898a996a 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -30,6 +30,7 @@ #include #include #include +#include #include #include #include --=20 2.51.1