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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: 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> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Stat-Signature: fhd3wtf976mtkoge4ezzrbahux1wctxd X-Rspam-User: X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 5665920006 X-HE-Tag: 1769381267-850725 X-HE-Meta: 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 NYH0Sdah 2o9DXeoPHfK1wYs4T9U81iKxq4NkxesuPEbS1SLkm5XfPgYEbhie1InynFtTlWr31a+Iavkr9RjN0dPiYlGAQDOh7jcXrekKp0aPnUsHo+6Cvz6P/kBxV9LIhnGTvzONcL7R/iocXIriDfxnouL7qXGoSrIHwzxDNqpBwQdYEZ8qmgz2tNz+VCFkEPq1dXVpgyMwqyUNzMoEXZRN1i5pS5DNhWtMIsvMCNk89Q5h+KY9SOKiVKBIfsFAYqmzZjXVQKZMuRfSk72phv8TOSh2t9t8blIqN/FPCZ0SwCSNNelczQHUitNU23hTwUeg8LR6n4I9/AE8eGRnpTSLwwQChXhyn+ToUalY6qSL36yQUNe84VOF6SJdzcLEFpg== 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. [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/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..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; - lockdep_assert_cpus_held(); - ret = workqueue_unbound_exclude_cpumask(isolated_cpus); WARN_ON_ONCE(ret < 0); 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 6f77289c14c3..674a02891b38 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 +110,45 @@ 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; + + lockdep_assert_cpus_held(); + + 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_cpuslocked(&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