Messages in this thread | | | Date | Mon, 6 Feb 2023 10:21:25 -1000 | From | Tejun Heo <> | Subject | Re: [PATCH 2/2] cpuset: Call set_cpus_allowed_ptr() with appropriate mask for task |
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On Tue, Jan 31, 2023 at 10:17:19PM +0000, Will Deacon wrote: > set_cpus_allowed_ptr() will fail with -EINVAL if the requested > affinity mask is not a subset of the task_cpu_possible_mask() for the > task being updated. Consequently, on a heterogeneous system with cpusets > spanning the different CPU types, updates to the cgroup hierarchy can > silently fail to update task affinities when the effective affinity > mask for the cpuset is expanded. > > For example, consider an arm64 system with 4 CPUs, where CPUs 2-3 are > the only cores capable of executing 32-bit tasks. Attaching a 32-bit > task to a cpuset containing CPUs 0-2 will correctly affine the task to > CPU 2. Extending the cpuset to CPUs 0-3, however, will fail to extend > the affinity mask of the 32-bit task because update_tasks_cpumask() will > pass the full 0-3 mask to set_cpus_allowed_ptr(). > > Extend update_tasks_cpumask() to take a temporary 'cpumask' paramater > and use it to mask the 'effective_cpus' mask with the possible mask for > each task being updated. > > Fixes: 431c69fac05b ("cpuset: Honour task_cpu_possible_mask() in guarantee_online_cpus()") > Signed-off-by: Will Deacon <will@kernel.org>
Applied to cgroup/for-6.2-fixes.
Thanks.
-- tejun
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