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Wysocki" , kernel-team@android.com Subject: Re: [PATCH v6 07/21] cpuset: Don't use the cpu_possible_mask as a last resort for cgroup v1 Message-ID: <20210521173934.pjcv37j63odtsrp6@e107158-lin.cambridge.arm.com> References: <20210518094725.7701-1-will@kernel.org> <20210518094725.7701-8-will@kernel.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20210518094725.7701-8-will@kernel.org> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210521_103941_355458_2A0B499E X-CRM114-Status: GOOD ( 19.45 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 05/18/21 10:47, Will Deacon wrote: > If the scheduler cannot find an allowed CPU for a task, > cpuset_cpus_allowed_fallback() will widen the affinity to cpu_possible_mask > if cgroup v1 is in use. > > In preparation for allowing architectures to provide their own fallback > mask, just return early if we're either using cgroup v1 or we're using > cgroup v2 with a mask that contains invalid CPUs. This will allow > select_fallback_rq() to figure out the mask by itself. > > Cc: Li Zefan > Cc: Tejun Heo > Cc: Johannes Weiner > Reviewed-by: Quentin Perret > Signed-off-by: Will Deacon > --- > include/linux/cpuset.h | 1 + > kernel/cgroup/cpuset.c | 12 ++++++++++-- > 2 files changed, 11 insertions(+), 2 deletions(-) > > diff --git a/include/linux/cpuset.h b/include/linux/cpuset.h > index 04c20de66afc..ed6ec677dd6b 100644 > --- a/include/linux/cpuset.h > +++ b/include/linux/cpuset.h > @@ -15,6 +15,7 @@ > #include > #include > #include > +#include > #include > > #ifdef CONFIG_CPUSETS > diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c > index a945504c0ae7..8c799260a4a2 100644 > --- a/kernel/cgroup/cpuset.c > +++ b/kernel/cgroup/cpuset.c > @@ -3322,9 +3322,17 @@ void cpuset_cpus_allowed(struct task_struct *tsk, struct cpumask *pmask) > > void cpuset_cpus_allowed_fallback(struct task_struct *tsk) > { > + const struct cpumask *cs_mask; > + const struct cpumask *possible_mask = task_cpu_possible_mask(tsk); > + > rcu_read_lock(); > - do_set_cpus_allowed(tsk, is_in_v2_mode() ? > - task_cs(tsk)->cpus_allowed : cpu_possible_mask); > + cs_mask = task_cs(tsk)->cpus_allowed; > + > + if (!is_in_v2_mode() || !cpumask_subset(cs_mask, possible_mask)) > + goto unlock; /* select_fallback_rq will try harder */ > + > + do_set_cpus_allowed(tsk, cs_mask); Shouldn't we take the intersection with possible_mask like we discussed before? https://lore.kernel.org/lkml/20201217145954.GA17881@willie-the-truck/ Thanks -- Qais Yousef > +unlock: > rcu_read_unlock(); > > /* > -- > 2.31.1.751.gd2f1c929bd-goog > _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel