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Cc: Guopeng Zhang , Ridong Chen , cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, Chen Ridong , Ridong Chen Subject: [RFC PATCH -v4 12/22] cpuset: use local_partition_disable() to invalidate local partition Date: Sun, 1 Nov 2026 19:41:56 +0800 Message-Id: <20261101114206.2434398-13-ridong.chen@linux.dev> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20261101114206.2434398-1-ridong.chen@linux.dev> References: <20261101114206.2434398-1-ridong.chen@linux.dev> X-Mailing-List: cgroups@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Chen Ridong Build on the local_partition_disable() infrastructure introduced in the previous patch to handle local partition invalidation, replacing partcmd_invalidate in partition_cpus_change() and cpuset_hotplug_update_tasks(). In cpuset_hotplug_update_tasks(), the partition error is now derived from the reason of the invalidation (PERR_INVPARENT, PERR_NOTPART, PERR_HOTPLUG or PERR_NOCPUS) and passed to local_partition_disable(), which sets prs_err together with the partition root state. As local_partition_disable() resets the partition data, the effective_xcpus of an invalid partition is no longer kept. When update_parent_effective_cpumask() turns an invalid partition back into a valid one, use partition_enable() to set up effective_xcpus and the partition state again. Additionally, correct the transition logic in cpuset_hotplug_update_tasks() when determining whether to transition an invalid partition root, the check should be based on non-empty user_xcpus rather than non-empty effective_xcpus. This correction addresses the scenario where exclusive_cpus is not set but cpus_allowed is configured. In this case, effective_xcpus may be empty even though the partition should be considered for re-enablement. The user_xcpus based check ensures proper partition state transitions under these conditions. Since partition_disable() gives the CPUs back to the parent and updates effective_cpus of the cpuset directly, save effective_cpus before any partition state change in cpuset_hotplug_update_tasks() and compare the new effective cpumask against it. Otherwise the tasks of a partition invalidated by hotplug may be left with only the offlined CPUs. Signed-off-by: Chen Ridong Signed-off-by: Ridong Chen --- kernel/cgroup/cpuset.c | 81 +++++++++++++++++++++++------------------- 1 file changed, 44 insertions(+), 37 deletions(-) diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c index 3d6ad6cd634a..822cc1d97fca 100644 --- a/kernel/cgroup/cpuset.c +++ b/kernel/cgroup/cpuset.c @@ -2133,23 +2133,6 @@ static int update_parent_effective_cpumask(struct cpuset *cs, int cmd, adding = deleting = false; old_prs = new_prs = cs->partition_root_state; - if (cmd == partcmd_invalidate) { - if (is_partition_invalid(cs)) - return 0; - - /* - * Make the current partition invalid. - */ - if (is_partition_valid(parent)) - adding = cpumask_and(tmp->addmask, - cs->effective_xcpus, - parent->effective_xcpus); - if (old_prs > 0) - new_prs = -old_prs; - - goto write_error; - } - /* * The parent must be a partition root. * The new cpumask, if present, or the current cpus_allowed must @@ -2340,20 +2323,28 @@ static int update_parent_effective_cpumask(struct cpuset *cs, int cmd, * Newly added CPUs will be removed from effective_cpus and * newly deleted ones will be added back to effective_cpus. */ - spin_lock_irq(&callback_lock); - if (old_prs != new_prs) - cs->partition_root_state = new_prs; + if ((old_prs < 0) && (new_prs > 0)) { + /* + * An invalid partition becomes valid again, its effective_xcpus + * was reset when it was invalidated. + */ + partition_enable(cs, parent, new_prs, tmp->delmask); + } else { + spin_lock_irq(&callback_lock); + if (old_prs != new_prs) + cs->partition_root_state = new_prs; - /* - * Adding to parent's effective_cpus means deletion CPUs from cs - * and vice versa. - */ - if (adding) - partition_xcpus_del(old_prs, parent, tmp->addmask); - if (deleting) - partition_xcpus_add(new_prs, parent, tmp->delmask); + /* + * Adding to parent's effective_cpus means deletion CPUs from cs + * and vice versa. + */ + if (adding) + partition_xcpus_del(old_prs, parent, tmp->addmask); + if (deleting) + partition_xcpus_add(new_prs, parent, tmp->delmask); - spin_unlock_irq(&callback_lock); + spin_unlock_irq(&callback_lock); + } if (adding || deleting) { cpuset_update_tasks_cpumask(parent, tmp->addmask); @@ -2657,8 +2648,7 @@ static void partition_cpus_change(struct cpuset *cs, struct cpuset *trialcs, trialcs->effective_xcpus, tmp); } else { if (trialcs->prs_err) - update_parent_effective_cpumask(cs, partcmd_invalidate, - NULL, tmp); + local_partition_disable(cs, trialcs->prs_err, tmp); else update_parent_effective_cpumask(cs, partcmd_update, trialcs->effective_xcpus, tmp); @@ -4089,7 +4079,7 @@ void cpuset_force_rebuild(void) */ static void cpuset_hotplug_update_tasks(struct cpuset *cs, struct tmpmasks *tmp) { - static cpumask_t new_cpus; + static cpumask_t new_cpus, old_cpus; static nodemask_t new_mems; bool cpus_updated; bool mems_updated; @@ -4098,6 +4088,11 @@ static void cpuset_hotplug_update_tasks(struct cpuset *cs, struct tmpmasks *tmp) wait_attach_done_lock(); parent = parent_cs(cs); + /* + * Partition state changes below may update effective_cpus directly, + * save it to check if tasks need to be updated. + */ + cpumask_copy(&old_cpus, cs->effective_cpus); compute_effective_cpumask(&new_cpus, cs, parent); compute_effective_nodemask(&new_mems, cs, parent); @@ -4123,18 +4118,30 @@ static void cpuset_hotplug_update_tasks(struct cpuset *cs, struct tmpmasks *tmp) if (is_local_partition(cs) && (!is_partition_valid(parent) || tasks_nocpu_error(parent, cs, &new_cpus) || - cpumask_empty(subpartitions_cpus))) + cpumask_empty(subpartitions_cpus))) { + enum prs_errcode prs_err; + + if (!is_partition_valid(parent)) + prs_err = is_partition_invalid(parent) + ? PERR_INVPARENT : PERR_NOTPART; + else if (cpumask_empty(subpartitions_cpus)) + prs_err = PERR_HOTPLUG; + else + prs_err = PERR_NOCPUS; partcmd = partcmd_invalidate; + local_partition_disable(cs, prs_err, tmp); + } /* * On the other hand, an invalid partition root may be transitioned - * back to a regular one with a non-empty effective xcpus. + * back to a regular one with a non-empty user xcpus. */ else if (is_partition_valid(parent) && is_partition_invalid(cs) && - !cpumask_empty(cs->effective_xcpus)) + !cpumask_empty(user_xcpus(cs))) { partcmd = partcmd_update; + update_parent_effective_cpumask(cs, partcmd, NULL, tmp); + } if (partcmd >= 0) { - update_parent_effective_cpumask(cs, partcmd, NULL, tmp); if (is_partition_valid(cs) || (partcmd == partcmd_invalidate)) { compute_effective_cpumask(&new_cpus, cs, parent); cpuset_force_rebuild(); @@ -4142,7 +4149,7 @@ static void cpuset_hotplug_update_tasks(struct cpuset *cs, struct tmpmasks *tmp) } update_tasks: - cpus_updated = !cpumask_equal(&new_cpus, cs->effective_cpus); + cpus_updated = !cpumask_equal(&new_cpus, &old_cpus); mems_updated = !nodes_equal(new_mems, cs->effective_mems); if (!cpus_updated && !mems_updated) goto unlock; /* Hotplug doesn't affect this cpuset */ -- 2.34.1