On Mon, Dec 12, 2022 at 09:07:11PM +0100, Peter Zijlstra wrote: > On Mon, Dec 12, 2022 at 08:03:24AM -1000, Tejun Heo wrote: > > On Mon, Dec 12, 2022 at 12:13:31PM +0100, Peter Zijlstra wrote: > > > On Tue, Nov 29, 2022 at 10:22:46PM -1000, Tejun Heo wrote: > > > > A new sched_clas needs a bit more control over forking. This patch makes the > > > ^ > > > (insufficient s's) > > > > Will update. > > > > > > following changes: > > > > > > > > * Add sched_cancel_fork() which is called if fork fails after sched_fork() > > > > succeeds so that the preparation can be undone. > > > > > > > > * Allow sched_cgroup_fork() to fail. > > > > > > > > Neither is used yet and this patch shouldn't cause any behavior changes. > > > > > > Fails to explain why this would be needed and why that would be a good > > > thing. IOW, total lack of justification. > > > > This is because sched_ext calls out to BPF scheduler's prepare_enable() > > operation to prepare the task. The operation is allowed to fail (e.g. it > > might need to allocate something which can fail), so we need a way back back > > out of it. > > sched_fork() can already fail; why isn't that a suitable location to do > what needs doing? Because SCX's ops.prepare_enable() wants the cgroup (p->sched_task_group) to be initialized in case the BPF scheduler wants to perform cgroup related initializations. Thanks. -- tejun
