Re: [PATCH 00/33 v6] cpuset/isolation: Honour kthreads preferred affinity

[Waiman Long]

On 1/12/26 5:09 PM, Frederic Weisbecker wrote:
> Le Mon, Jan 12, 2026 at 01:23:40PM -0500, Waiman Long a écrit :
> > On 1/1/26 5:13 PM, Frederic Weisbecker wrote:
> > > Hi,
> > >
> > > The kthread code was enhanced lately to provide an infrastructure which
> > > manages the preferred affinity of unbound kthreads (node or custom
> > > cpumask) against housekeeping constraints and CPU hotplug events.
> > >
> > > One crucial missing piece is cpuset: when an isolated partition is
> > > created, deleted, or its CPUs updated, all the unbound kthreads in the
> > > top cpuset are affine to _all_ the non-isolated CPUs, possibly breaking
> > > their preferred affinity along the way
> > >
> > > Solve this with performing the kthreads affinity update from cpuset to
> > > the kthreads consolidated relevant code instead so that preferred
> > > affinities are honoured.
> > >
> > > The dispatch of the new cpumasks to workqueues and kthreads is performed
> > > by housekeeping, as per the nice Tejun's suggestion.
> > >
> > > As a welcome side effect, HK_TYPE_DOMAIN then integrates both the set
> > > from isolcpus= and cpuset isolated partitions. Housekeeping cpumasks are
> > > now modifyable with specific synchronization. A big step toward making
> > > nohz_full= also mutable through cpuset in the future.
> > >
> > > Changes since v5:
> > >
> > > * Add more tags
> > >
> > > * Fix leaked destroy_work_on_stack() (Zhang Qiao, Waiman Long)
> > >
> > > * Comment schedule_drain_work() synchronization requirement (Tejun)
> > >
> > > * s/Revert of/Inverse of (Waiman Long)
> > >
> > > * Remove housekeeping_update() needless (for now) parameter (Chen Ridong)
> > >
> > > * Don't propagate housekeeping_update() failures beyond allocations (Waiman Long)
> > >
> > > * Whitespace cleanup (Waiman Long)
> > >
> > >
> > > git://git.kernel.org/pub/scm/linux/kernel/git/frederic/linux-dynticks.git
> > > 	kthread/core-v6
> > >
> > > HEAD: 811e87ca8a0a1e54eb5f23e71896cb97436cccdc
> > >
> > > Happy new year,
> > > 	Frederic
> > I don't see any major issue with this v6 version. There may be some minor
> > issues that can be cleaned up later. Now the issue is which tree should this
> > series go to as it touches a number of different subsystems with different
> > maintainers.
> It indeed crosses many subsystems. I would be fine if anybody takes it but
> nobody volunteered so far.
>
> The main purpose is to fix kthreads affinity (HK_TYPE_DOMAIN handling cpuset is
> a bonus). And since I made the pull request myself to Linus when I introduced
> kthreads managed affinity, I guess I could reiterate with this patchset. I
> already pushed it to linux-next.
>
> But if anybody wants to pull that to another tree, that's fine, just tell me
> so that we synchronize to avoid duplication on linux-next.
>
> Thanks.

Good to know as I am wondering where it will go. So you are going to 
push that directly to Linus.

Cheers,
Longman