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Cc: cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, Chen Ridong , Ridong Chen References: <20261101114206.2434398-1-ridong.chen@linux.dev> <20261101114206.2434398-5-ridong.chen@linux.dev> Content-Language: en-US From: Guopeng Zhang In-Reply-To: <20261101114206.2434398-5-ridong.chen@linux.dev> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 在 2026/11/1 19:41, Ridong Chen 写道: > From: Chen Ridong > > Add partition_enable() to consolidate updates to key cpuset structures > during partition enablement, including: > 1. remote_partition > 2. effective_xcpus > 3. partition_root_state > 4. prs_err > > Key operations performed: > 1. Invokes partition_xcpus_add() to assign exclusive CPUs > 2. Maintains remote partition flag > 3. Syncs the effective_xcpus mask > 4. Updates partition_root_state and prs_err > 5. Triggers scheduler domain rebuilds > 6. Sends partition change notifications > > This helper also handles the transition between root and isolated > states of a valid partition. In that case the cpumasks are unchanged > and only isolated_cpus is updated. > > A partition_state_update() helper is added to set partition_root_state > and prs_err, and to reset the partition data when the new state is not > a valid partition. > > Signed-off-by: Chen Ridong > Signed-off-by: Ridong Chen > --- > kernel/cgroup/cpuset.c | 51 ++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 51 insertions(+) > > diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c > index df52f6e5e99f..052a131731dd 100644 > --- a/kernel/cgroup/cpuset.c > +++ b/kernel/cgroup/cpuset.c > @@ -1716,6 +1716,57 @@ static void compute_effective_nodemask(nodemask_t *new_mems, > nodes_copy(*new_mems, parent->effective_mems); > } > > +static void partition_state_update(struct cpuset *cs, int new_prs, > + enum prs_errcode prs_err) > +{ > + lockdep_assert_held(&callback_lock); > + > + cs->partition_root_state = new_prs; > + WRITE_ONCE(cs->prs_err, prs_err); > + if (!is_partition_valid(cs)) > + reset_partition_data(cs); > +} > + > +/** > + * partition_enable - Transitions a cpuset to a partition root > + * @cs: The cpuset to enable partition for > + * @parent: Parent cpuset of @cs, NULL for remote parent > + * @new_prs: New partition state to set > + * @new_excpus: New effective exclusive CPUs mask for the partition > + * > + * Transitions a cpuset to a partition root, only for v2. > + * It also supports the transition between root and isolated partition. > + */ > +static void partition_enable(struct cpuset *cs, struct cpuset *parent, > + int new_prs, struct cpumask *new_excpus) Should we consider the bisection case here? With CONFIG_WERROR=y this patch fails to build on its own — partition_enable() is defined but not used. Thanks, Guopeng > +{ > + int old_prs = cs->partition_root_state; > + > + lockdep_assert_cpuset_lock_held(); > + WARN_ON_ONCE(new_prs <= 0); > + WARN_ON_ONCE(!cpuset_v2()); > + > + if (old_prs == new_prs) > + return; > + > + spin_lock_irq(&callback_lock); > + if (old_prs > 0) { > + /* Switch between root and isolated, cpumasks are unchanged */ > + isolated_cpus_update(old_prs, new_prs, cs->effective_xcpus); > + } else { > + /* enable partition should only add exclusive cpus */ > + partition_xcpus_add(new_prs, parent, new_excpus); > + /* enable remote partition */ > + if (!parent) > + cs->remote_partition = true; > + cpumask_copy(cs->effective_xcpus, new_excpus); > + } > + partition_state_update(cs, new_prs, PERR_NONE); > + spin_unlock_irq(&callback_lock); > + cpuset_force_rebuild(); > + notify_partition_change(cs, old_prs); > +} > + > /* > * remote_partition_enable - Enable current cpuset as a remote partition root > * @cs: the cpuset to update