user/sven/linux.git/kernel/sched, branch v6.12.71

sched/deadline: Fix 'stuck' dl_server

2026-02-06T15:55:44Z

[ Upstream commit 115135422562e2f791e98a6f55ec57b2da3b3a95 ] Andrea reported the dl_server getting stuck for him. He tracked it down to a state where dl_server_start() saw dl_defer_running==1, but the dl_server's job is no longer valid at the time of dl_server_start(). In the state diagram this corresponds to [4] D->A (or dl_server_stop() due to no more runnable tasks) followed by [1], which in case of a lapsed deadline must then be A->B. Now our A has dl_defer_running==1, while B demands dl_defer_running==0, therefore it must get cleared when the CBS wakeup rules demand a replenish. Fixes: a110a81c52a9 ("sched/deadline: Deferrable dl server") Reported-by: Andrea Righi arighi@nvidia.com Signed-off-by: Peter Zijlstra (Intel) Acked-by: Juri Lelli Tested-by: Andrea Righi arighi@nvidia.com Link: https://lkml.kernel.org/r/20260123161645.2181752-1-arighi@nvidia.com Link: https://patch.msgid.link/20260130124100.GC1079264@noisy.programming.kicks-ass.net Signed-off-by: Sasha Levin

sched/deadline: Document dl_server

2026-02-06T15:55:44Z

[ Upstream commit 2614069c5912e9d6f1f57c262face1b368fb8c93 ] Place the notes that resulted from going through the dl_server code in a comment. Signed-off-by: Peter Zijlstra (Intel) Stable-dep-of: 115135422562 ("sched/deadline: Fix 'stuck' dl_server") Signed-off-by: Sasha Levin

sched_ext: Fix possible deadlock in the deferred_irq_workfn()

2026-01-30T09:28:48Z

[ Upstream commit a257e974210320ede524f340ffe16bf4bf0dda1e ] For PREEMPT_RT=y kernels, the deferred_irq_workfn() is executed in the per-cpu irq_work/* task context and not disable-irq, if the rq returned by container_of() is current CPU's rq, the following scenarios may occur: lock(&rq->__lock); lock(&rq->__lock); This commit use IRQ_WORK_INIT_HARD() to replace init_irq_work() to initialize rq->scx.deferred_irq_work, make the deferred_irq_workfn() is always invoked in hard-irq context. Signed-off-by: Zqiang Signed-off-by: Tejun Heo Signed-off-by: Chen Yu Signed-off-by: Greg Kroah-Hartman

sched/fair: Fix pelt clock sync when entering idle

2026-01-30T09:28:42Z

[ Upstream commit 98c88dc8a1ace642d9021b103b28cba7b51e3abc ] Samuel and Alex reported regressions of the util_avg of RT rq with commit 17e3e88ed0b6 ("sched/fair: Fix pelt lost idle time detection"). It happens that fair is updating and syncing the pelt clock with task one when pick_next_task_fair() fails to pick a task but before the prev scheduling class got a chance to update its pelt signals. Move update_idle_rq_clock_pelt() in set_next_task_idle() which is called after prev class has been called. Fixes: 17e3e88ed0b6 ("sched/fair: Fix pelt lost idle time detection") Closes: https://lore.kernel.org/all/CAG2KctpO6VKS6GN4QWDji0t92_gNBJ7HjjXrE+6H+RwRXt=iLg@mail.gmail.com/ Closes: https://lore.kernel.org/all/8cf19bf0e0054dcfed70e9935029201694f1bb5a.camel@mediatek.com/ Reported-by: Samuel Wu Reported-by: Alex Hoh Signed-off-by: Vincent Guittot Signed-off-by: Peter Zijlstra (Intel) Tested-by: Samuel Wu Tested-by: Alex Hoh Link: https://patch.msgid.link/20260121163317.505635-1-vincent.guittot@linaro.org Signed-off-by: Sasha Levin

sched/fair: Proportional newidle balance

2026-01-11T14:25:21Z

commit 33cf66d88306663d16e4759e9d24766b0aaa2e17 upstream. Add a randomized algorithm that runs newidle balancing proportional to its success rate. This improves schbench significantly: 6.18-rc4: 2.22 Mrps/s 6.18-rc4+revert: 2.04 Mrps/s 6.18-rc4+revert+random: 2.18 Mrps/S Conversely, per Adam Li this affects SpecJBB slightly, reducing it by 1%: 6.17: -6% 6.17+revert: 0% 6.17+revert+random: -1% Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Dietmar Eggemann Tested-by: Dietmar Eggemann Tested-by: Chris Mason Link: https://lkml.kernel.org/r/6825c50d-7fa7-45d8-9b81-c6e7e25738e2@meta.com Link: https://patch.msgid.link/20251107161739.770122091@infradead.org [ Ajay: Modified to apply on v6.12 ] Signed-off-by: Ajay Kaher Signed-off-by: Greg Kroah-Hartman

sched/fair: Small cleanup to update_newidle_cost()

2026-01-11T14:25:21Z

commit 08d473dd8718e4a4d698b1113a14a40ad64a909b upstream. Simplify code by adding a few variables. Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Dietmar Eggemann Tested-by: Dietmar Eggemann Tested-by: Chris Mason Link: https://patch.msgid.link/20251107161739.655208666@infradead.org [ Ajay: Modified to apply on v6.12 ] Signed-off-by: Ajay Kaher Signed-off-by: Greg Kroah-Hartman

sched/fair: Small cleanup to sched_balance_newidle()

2026-01-11T14:25:21Z

commit e78e70dbf603c1425f15f32b455ca148c932f6c1 upstream. Pull out the !sd check to simplify code. Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Dietmar Eggemann Tested-by: Dietmar Eggemann Tested-by: Chris Mason Link: https://patch.msgid.link/20251107161739.525916173@infradead.org [ Ajay: Modified to apply on v6.12 ] Signed-off-by: Ajay Kaher Signed-off-by: Greg Kroah-Hartman

sched_ext: Fix missing post-enqueue handling in move_local_task_to_local_dsq()

2026-01-08T09:14:58Z

[ Upstream commit f5e1e5ec204da11fa87fdf006d451d80ce06e118 ] move_local_task_to_local_dsq() is used when moving a task from a non-local DSQ to a local DSQ on the same CPU. It directly manipulates the local DSQ without going through dispatch_enqueue() and was missing the post-enqueue handling that triggers preemption when SCX_ENQ_PREEMPT is set or the idle task is running. The function is used by move_task_between_dsqs() which backs scx_bpf_dsq_move() and may be called while the CPU is busy. Add local_dsq_post_enq() call to move_local_task_to_local_dsq(). As the dispatch path doesn't need post-enqueue handling, add SCX_RQ_IN_BALANCE early exit to keep consume_dispatch_q() behavior unchanged and avoid triggering unnecessary resched when scx_bpf_dsq_move() is used from the dispatch path. Fixes: 4c30f5ce4f7a ("sched_ext: Implement scx_bpf_dispatch[_vtime]_from_dsq()") Cc: stable@vger.kernel.org # v6.12+ Reviewed-by: Andrea Righi Reviewed-by: Emil Tsalapatis Signed-off-by: Tejun Heo Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

sched_ext: Factor out local_dsq_post_enq() from dispatch_enqueue()

2026-01-08T09:14:58Z

[ Upstream commit 530b6637c79e728d58f1d9b66bd4acf4b735b86d ] Factor out local_dsq_post_enq() which performs post-enqueue handling for local DSQs - triggering resched_curr() if SCX_ENQ_PREEMPT is specified or if the current CPU is idle. No functional change. This will be used by the next patch to fix move_local_task_to_local_dsq(). Cc: stable@vger.kernel.org # v6.12+ Reviewed-by: Andrea Righi Reviewed-by: Emil Tsalapatis Signed-off-by: Tejun Heo Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

sched_ext: Fix incorrect sched_class settings for per-cpu migration tasks

2026-01-08T09:14:56Z

[ Upstream commit 1dd6c84f1c544e552848a8968599220bd464e338 ] When loading the ebpf scheduler, the tasks in the scx_tasks list will be traversed and invoke __setscheduler_class() to get new sched_class. however, this would also incorrectly set the per-cpu migration task's->sched_class to rt_sched_class, even after unload, the per-cpu migration task's->sched_class remains sched_rt_class. The log for this issue is as follows: ./scx_rustland --stats 1 [ 199.245639][ T630] sched_ext: "rustland" does not implement cgroup cpu.weight [ 199.269213][ T630] sched_ext: BPF scheduler "rustland" enabled 04:25:09 [INFO] RustLand scheduler attached bpftrace -e 'iter:task /strcontains(ctx->task->comm, "migration")/ { printf("%s:%d->%pS\n", ctx->task->comm, ctx->task->pid, ctx->task->sched_class); }' Attaching 1 probe... migration/0:24->rt_sched_class+0x0/0xe0 migration/1:27->rt_sched_class+0x0/0xe0 migration/2:33->rt_sched_class+0x0/0xe0 migration/3:39->rt_sched_class+0x0/0xe0 migration/4:45->rt_sched_class+0x0/0xe0 migration/5:52->rt_sched_class+0x0/0xe0 migration/6:58->rt_sched_class+0x0/0xe0 migration/7:64->rt_sched_class+0x0/0xe0 sched_ext: BPF scheduler "rustland" disabled (unregistered from user space) EXIT: unregistered from user space 04:25:21 [INFO] Unregister RustLand scheduler bpftrace -e 'iter:task /strcontains(ctx->task->comm, "migration")/ { printf("%s:%d->%pS\n", ctx->task->comm, ctx->task->pid, ctx->task->sched_class); }' Attaching 1 probe... migration/0:24->rt_sched_class+0x0/0xe0 migration/1:27->rt_sched_class+0x0/0xe0 migration/2:33->rt_sched_class+0x0/0xe0 migration/3:39->rt_sched_class+0x0/0xe0 migration/4:45->rt_sched_class+0x0/0xe0 migration/5:52->rt_sched_class+0x0/0xe0 migration/6:58->rt_sched_class+0x0/0xe0 migration/7:64->rt_sched_class+0x0/0xe0 This commit therefore generate a new scx_setscheduler_class() and add check for stop_sched_class to replace __setscheduler_class(). Fixes: f0e1a0643a59 ("sched_ext: Implement BPF extensible scheduler class") Cc: stable@vger.kernel.org # v6.12+ Signed-off-by: Zqiang Reviewed-by: Andrea Righi Signed-off-by: Tejun Heo [ Adjust context ] Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman