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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: Thu, 1 Jan 2026 23:13:39 +0100 Message-ID: <20260101221359.22298-15-frederic@kernel.org> X-Mailer: git-send-email 2.51.1 In-Reply-To: <20260101221359.22298-1-frederic@kernel.org> References: <20260101221359.22298-1-frederic@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: 9B2FDA000A X-Rspamd-Server: rspam03 X-Stat-Signature: 1brgu4n5rradkxr7wpaoyh5i8oiom7jg X-Rspam-User: X-HE-Tag: 1767305770-314703 X-HE-Meta: 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 Q7ermOHo aqd69KIV3NkN9PqIekHq0CJR9uuunZa8Y/UcmGyFAbnSJEkxp5xpG8ejvky5l/sMeB+EFCYt/hlJt4UjuGe4tJoCRMRoEfSWOf4kIT2VuTpAZUxKohWmoq4oPiZWSwlDjYaA4ussdXx0gTGp8afvYXAwfIkVrmSW4KJ+vOykpUf+oAzvNyFWsUwjYyFS4SJeusnxDQeypAJ/sehqrreTRrrIdVbtv6m1ObMWXlSfKO9Y2JJ+NgIitZp1DmPBgWzI9uYjhUJEPu3fQceDy+dPT1LYTXQQlFgDSKfBWxGV3Ao7ZzB+k4AeyQWBrevK2u8pQyYWtpRPdx4SQFd49XzFtAZLNbcmvZqdS8Zb61EKxZexNI7ni1go2Ie6ZEQ== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 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 Reviewed-by: Waiman Long Reviewed-by: Chen Ridong --- include/linux/sched/isolation.h | 7 ++++ kernel/cgroup/cpuset.c | 3 ++ kernel/sched/isolation.c | 73 ++++++++++++++++++++++++++++++--- kernel/sched/sched.h | 1 + 4 files changed, 78 insertions(+), 6 deletions(-) diff --git a/include/linux/sched/isolation.h b/include/linux/sched/isolation.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= 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=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 *isol_mask); 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 *isol_mask) { 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 5e2e3514c22e..1c0475e384dc 100644 --- a/kernel/cgroup/cpuset.c +++ b/kernel/cgroup/cpuset.c @@ -1490,6 +1490,9 @@ static void update_isolation_cpumasks(void) ret = tmigr_isolated_exclude_cpumask(isolated_cpus); WARN_ON_ONCE(ret < 0); + ret = housekeeping_update(isolated_cpus); + WARN_ON_ONCE(ret < 0); + isolated_cpus_updating = false; } diff --git a/kernel/sched/isolation.c b/kernel/sched/isolation.c index 83be49ec2b06..c61b7ef3e98e 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 +110,43 @@ 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 *isol_mask) +{ + struct cpumask *trial, *old = NULL; + + trial = kmalloc(cpumask_size(), GFP_KERNEL); + if (!trial) + return -ENOMEM; + + cpumask_andnot(trial, housekeeping_cpumask(HK_TYPE_DOMAIN_BOOT), isol_mask); + if (!cpumask_intersects(trial, cpu_online_mask)) { + kfree(trial); + return -EINVAL; + } + + if (!housekeeping.flags) + static_branch_enable(&housekeeping_overridden); + + if (housekeeping.flags & HK_FLAG_DOMAIN) + old = 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 -- 2.51.1