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e32cde8d2b
- When sched_ext is in bypass mode (e.g. while disabling the BPF scheduler), it was using one DSQ to implement global FIFO scheduling as all it has to do is guaranteeing reasonable forward progress. On multi-socket machines, this can lead to live-lock conditions under certain workloads. Fixed by splitting the queue used for FIFO scheduling per NUMA node. This required several preparation patches. - Hotplug tests on powerpc could reliably trigger deadlock while enabling a BPF scheduler. This was caused by cpu_hotplug_lock nesting inside scx_fork_rwsem and then CPU hotplug path trying to fork a new thread while holding cpu_hotplug_lock. Fixed by restructuring locking in enable and disable paths so that the two locks are not coupled. This required several preparation patches which also fixed a couple other issues in the enable path. - A build fix for !CONFIG_SMP. - Userspace tooling sync and updates. -----BEGIN PGP SIGNATURE----- iIQEABYKACwWIQTfIjM1kS57o3GsC/uxYfJx3gVYGQUCZvsB8A4cdGpAa2VybmVs Lm9yZwAKCRCxYfJx3gVYGW0cAP9LWESwNvszp0jDglg8kvS6tyHDLNQYLT99Dy4Q NPE1OgD+KUKXuRBOhT3dc9dbwodmPtX2rq36QIgHhoGiPB9hew8= =NH+o -----END PGP SIGNATURE----- Merge tag 'sched_ext-for-6.12-rc1-fixes-1' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext Pull sched_ext fixes from Tejun Heo: - When sched_ext is in bypass mode (e.g. while disabling the BPF scheduler), it was using one DSQ to implement global FIFO scheduling as all it has to do is guaranteeing reasonable forward progress. On multi-socket machines, this can lead to live-lock conditions under certain workloads. Fixed by splitting the queue used for FIFO scheduling per NUMA node. This required several preparation patches. - Hotplug tests on powerpc could reliably trigger deadlock while enabling a BPF scheduler. This was caused by cpu_hotplug_lock nesting inside scx_fork_rwsem and then CPU hotplug path trying to fork a new thread while holding cpu_hotplug_lock. Fixed by restructuring locking in enable and disable paths so that the two locks are not coupled. This required several preparation patches which also fixed a couple other issues in the enable path. - A build fix for !CONFIG_SMP - Userspace tooling sync and updates * tag 'sched_ext-for-6.12-rc1-fixes-1' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext: sched_ext: Remove redundant p->nr_cpus_allowed checker sched_ext: Decouple locks in scx_ops_enable() sched_ext: Decouple locks in scx_ops_disable_workfn() sched_ext: Add scx_cgroup_enabled to gate cgroup operations and fix scx_tg_online() sched_ext: Enable scx_ops_init_task() separately sched_ext: Fix SCX_TASK_INIT -> SCX_TASK_READY transitions in scx_ops_enable() sched_ext: Initialize in bypass mode sched_ext: Remove SCX_OPS_PREPPING sched_ext: Relocate check_hotplug_seq() call in scx_ops_enable() sched_ext: Use shorter slice while bypassing sched_ext: Split the global DSQ per NUMA node sched_ext: Relocate find_user_dsq() sched_ext: Allow only user DSQs for scx_bpf_consume(), scx_bpf_dsq_nr_queued() and bpf_iter_scx_dsq_new() scx_flatcg: Use a user DSQ for fallback instead of SCX_DSQ_GLOBAL tools/sched_ext: Receive misc updates from SCX repo sched_ext: Add __COMPAT helpers for features added during v6.12 devel cycle sched_ext: Build fix for !CONFIG_SMP