user/sven/linux.git/kernel/sched, branch v6.4.15

cgroup/cpuset: Free DL BW in case can_attach() fails

2023-08-30T12:52:39Z

commit 2ef269ef1ac006acf974793d975539244d77b28f upstream. cpuset_can_attach() can fail. Postpone DL BW allocation until all tasks have been checked. DL BW is not allocated per-task but as a sum over all DL tasks migrating. If multiple controllers are attached to the cgroup next to the cpuset controller a non-cpuset can_attach() can fail. In this case free DL BW in cpuset_cancel_attach(). Finally, update cpuset DL task count (nr_deadline_tasks) only in cpuset_attach(). Suggested-by: Waiman Long Signed-off-by: Dietmar Eggemann Signed-off-by: Juri Lelli Reviewed-by: Waiman Long Signed-off-by: Tejun Heo Signed-off-by: Qais Yousef (Google) Signed-off-by: Greg Kroah-Hartman

sched/deadline: Create DL BW alloc, free & check overflow interface

2023-08-30T12:52:39Z

commit 85989106feb734437e2d598b639991b9185a43a6 upstream. While moving a set of tasks between exclusive cpusets, cpuset_can_attach() -> task_can_attach() calls dl_cpu_busy(..., p) for DL BW overflow checking and per-task DL BW allocation on the destination root_domain for the DL tasks in this set. This approach has the issue of not freeing already allocated DL BW in the following error cases: (1) The set of tasks includes multiple DL tasks and DL BW overflow checking fails for one of the subsequent DL tasks. (2) Another controller next to the cpuset controller which is attached to the same cgroup fails in its can_attach(). To address this problem rework dl_cpu_busy(): (1) Split it into dl_bw_check_overflow() & dl_bw_alloc() and add a dedicated dl_bw_free(). (2) dl_bw_alloc() & dl_bw_free() take a `u64 dl_bw` parameter instead of a `struct task_struct *p` used in dl_cpu_busy(). This allows to allocate DL BW for a set of tasks too rather than only for a single task. Signed-off-by: Dietmar Eggemann Signed-off-by: Juri Lelli Signed-off-by: Tejun Heo Signed-off-by: Qais Yousef (Google) Signed-off-by: Greg Kroah-Hartman

sched/cpuset: Keep track of SCHED_DEADLINE task in cpusets

2023-08-30T12:52:38Z

commit 6c24849f5515e4966d94fa5279bdff4acf2e9489 upstream. Qais reported that iterating over all tasks when rebuilding root domains for finding out which ones are DEADLINE and need their bandwidth correctly restored on such root domains can be a costly operation (10+ ms delays on suspend-resume). To fix the problem keep track of the number of DEADLINE tasks belonging to each cpuset and then use this information (followup patch) to only perform the above iteration if DEADLINE tasks are actually present in the cpuset for which a corresponding root domain is being rebuilt. Reported-by: Qais Yousef (Google) Link: https://lore.kernel.org/lkml/20230206221428.2125324-1-qyousef@layalina.io/ Signed-off-by: Juri Lelli Reviewed-by: Waiman Long Signed-off-by: Tejun Heo Signed-off-by: Qais Yousef (Google) Signed-off-by: Greg Kroah-Hartman

sched/cpuset: Bring back cpuset_mutex

2023-08-30T12:52:38Z

commit 111cd11bbc54850f24191c52ff217da88a5e639b upstream. Turns out percpu_cpuset_rwsem - commit 1243dc518c9d ("cgroup/cpuset: Convert cpuset_mutex to percpu_rwsem") - wasn't such a brilliant idea, as it has been reported to cause slowdowns in workloads that need to change cpuset configuration frequently and it is also not implementing priority inheritance (which causes troubles with realtime workloads). Convert percpu_cpuset_rwsem back to regular cpuset_mutex. Also grab it only for SCHED_DEADLINE tasks (other policies don't care about stable cpusets anyway). Signed-off-by: Juri Lelli Reviewed-by: Waiman Long Signed-off-by: Tejun Heo Signed-off-by: Qais Yousef (Google) Signed-off-by: Greg Kroah-Hartman

sched/psi: use kernfs polling functions for PSI trigger polling

2023-07-27T06:56:53Z

[ Upstream commit aff037078ecaecf34a7c2afab1341815f90fba5e ] Destroying psi trigger in cgroup_file_release causes UAF issues when a cgroup is removed from under a polling process. This is happening because cgroup removal causes a call to cgroup_file_release while the actual file is still alive. Destroying the trigger at this point would also destroy its waitqueue head and if there is still a polling process on that file accessing the waitqueue, it will step on the freed pointer: do_select vfs_poll do_rmdir cgroup_rmdir kernfs_drain_open_files cgroup_file_release cgroup_pressure_release psi_trigger_destroy wake_up_pollfree(&t->event_wait) // vfs_poll is unblocked synchronize_rcu kfree(t) poll_freewait -> UAF access to the trigger's waitqueue head Patch [1] fixed this issue for epoll() case using wake_up_pollfree(), however the same issue exists for synchronous poll() case. The root cause of this issue is that the lifecycles of the psi trigger's waitqueue and of the file associated with the trigger are different. Fix this by using kernfs_generic_poll function when polling on cgroup-specific psi triggers. It internally uses kernfs_open_node->poll waitqueue head with its lifecycle tied to the file's lifecycle. This also renders the fix in [1] obsolete, so revert it. [1] commit c2dbe32d5db5 ("sched/psi: Fix use-after-free in ep_remove_wait_queue()") Fixes: 0e94682b73bf ("psi: introduce psi monitor") Closes: https://lore.kernel.org/all/20230613062306.101831-1-lujialin4@huawei.com/ Reported-by: Lu Jialin Signed-off-by: Suren Baghdasaryan Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/20230630005612.1014540-1-surenb@google.com Signed-off-by: Sasha Levin

sched/fair: Use recent_used_cpu to test p->cpus_ptr

2023-07-27T06:56:53Z

[ Upstream commit ae2ad293d6be143ad223f5f947cca07bcbe42595 ] When checking whether a recently used CPU can be a potential idle candidate, recent_used_cpu should be used to test p->cpus_ptr as p->recent_used_cpu is not equal to recent_used_cpu and candidate decision is made based on recent_used_cpu here. Fixes: 89aafd67f28c ("sched/fair: Use prev instead of new target as recent_used_cpu") Signed-off-by: Miaohe Lin Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Phil Auld Acked-by: Mel Gorman Link: https://lore.kernel.org/r/20230620080747.359122-1-linmiaohe@huawei.com Signed-off-by: Sasha Levin

sched/fair: Don't balance task to its current running CPU

2023-07-27T06:56:48Z

[ Upstream commit 0dd37d6dd33a9c23351e6115ae8cdac7863bc7de ] We've run into the case that the balancer tries to balance a migration disabled task and trigger the warning in set_task_cpu() like below: ------------[ cut here ]------------ WARNING: CPU: 7 PID: 0 at kernel/sched/core.c:3115 set_task_cpu+0x188/0x240 Modules linked in: hclgevf xt_CHECKSUM ipt_REJECT nf_reject_ipv4 <...snip> CPU: 7 PID: 0 Comm: swapper/7 Kdump: loaded Tainted: G O 6.1.0-rc4+ #1 Hardware name: Huawei TaiShan 2280 V2/BC82AMDC, BIOS 2280-V2 CS V5.B221.01 12/09/2021 pstate: 604000c9 (nZCv daIF +PAN -UAO -TCO -DIT -SSBS BTYPE=--) pc : set_task_cpu+0x188/0x240 lr : load_balance+0x5d0/0xc60 sp : ffff80000803bc70 x29: ffff80000803bc70 x28: ffff004089e190e8 x27: ffff004089e19040 x26: ffff007effcabc38 x25: 0000000000000000 x24: 0000000000000001 x23: ffff80000803be84 x22: 000000000000000c x21: ffffb093e79e2a78 x20: 000000000000000c x19: ffff004089e19040 x18: 0000000000000000 x17: 0000000000001fad x16: 0000000000000030 x15: 0000000000000000 x14: 0000000000000003 x13: 0000000000000000 x12: 0000000000000000 x11: 0000000000000001 x10: 0000000000000400 x9 : ffffb093e4cee530 x8 : 00000000fffffffe x7 : 0000000000ce168a x6 : 000000000000013e x5 : 00000000ffffffe1 x4 : 0000000000000001 x3 : 0000000000000b2a x2 : 0000000000000b2a x1 : ffffb093e6d6c510 x0 : 0000000000000001 Call trace: set_task_cpu+0x188/0x240 load_balance+0x5d0/0xc60 rebalance_domains+0x26c/0x380 _nohz_idle_balance.isra.0+0x1e0/0x370 run_rebalance_domains+0x6c/0x80 __do_softirq+0x128/0x3d8 ____do_softirq+0x18/0x24 call_on_irq_stack+0x2c/0x38 do_softirq_own_stack+0x24/0x3c __irq_exit_rcu+0xcc/0xf4 irq_exit_rcu+0x18/0x24 el1_interrupt+0x4c/0xe4 el1h_64_irq_handler+0x18/0x2c el1h_64_irq+0x74/0x78 arch_cpu_idle+0x18/0x4c default_idle_call+0x58/0x194 do_idle+0x244/0x2b0 cpu_startup_entry+0x30/0x3c secondary_start_kernel+0x14c/0x190 __secondary_switched+0xb0/0xb4 ---[ end trace 0000000000000000 ]--- Further investigation shows that the warning is superfluous, the migration disabled task is just going to be migrated to its current running CPU. This is because that on load balance if the dst_cpu is not allowed by the task, we'll re-select a new_dst_cpu as a candidate. If no task can be balanced to dst_cpu we'll try to balance the task to the new_dst_cpu instead. In this case when the migration disabled task is not on CPU it only allows to run on its current CPU, load balance will select its current CPU as new_dst_cpu and later triggers the warning above. The new_dst_cpu is chosen from the env->dst_grpmask. Currently it contains CPUs in sched_group_span() and if we have overlapped groups it's possible to run into this case. This patch makes env->dst_grpmask of group_balance_mask() which exclude any CPUs from the busiest group and solve the issue. For balancing in a domain with no overlapped groups the behaviour keeps same as before. Suggested-by: Vincent Guittot Signed-off-by: Yicong Yang Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Vincent Guittot Link: https://lore.kernel.org/r/20230530082507.10444-1-yangyicong@huawei.com Signed-off-by: Sasha Levin

sched/core: Avoid multiple calling update_rq_clock() in __cfsb_csd_unthrottle()

2023-07-19T14:35:20Z

[ Upstream commit ebb83d84e49b54369b0db67136a5fe1087124dcc ] After commit 8ad075c2eb1f ("sched: Async unthrottling for cfs bandwidth"), we may update the rq clock multiple times in the loop of __cfsb_csd_unthrottle(). A prior (although less common) instance of this problem exists in unthrottle_offline_cfs_rqs(). Cure both by ensuring update_rq_clock() is called before the loop and setting RQCF_ACT_SKIP during the loop, to supress further updates. The alternative would be pulling update_rq_clock() out of unthrottle_cfs_rq(), but that gives an even bigger mess. Fixes: 8ad075c2eb1f ("sched: Async unthrottling for cfs bandwidth") Reviewed-By: Ben Segall Suggested-by: Vincent Guittot Signed-off-by: Hao Jia Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Vincent Guittot Link: https://lkml.kernel.org/r/20230613082012.49615-4-jiahao.os@bytedance.com Signed-off-by: Sasha Levin

sched: fix cid_lock kernel-doc warnings

2023-05-08T08:58:28Z

Fix kernel-doc warnings for cid_lock and use_cid_lock. These comments are not in kernel-doc format. kernel/sched/core.c:11496: warning: Cannot understand * @cid_lock: Guarantee forward-progress of cid allocation. on line 11496 - I thought it was a doc line kernel/sched/core.c:11505: warning: Cannot understand * @use_cid_lock: Select cid allocation behavior: lock-free vs spinlock. on line 11505 - I thought it was a doc line Fixes: 223baf9d17f2 ("sched: Fix performance regression introduced by mm_cid") Signed-off-by: Randy Dunlap Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/20230428031111.322-1-rdunlap@infradead.org

Merge tag 'smp-core-2023-04-27' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2023-04-28T22:03:43Z

Pull SMP cross-CPU function-call updates from Ingo Molnar: - Remove diagnostics and adjust config for CSD lock diagnostics - Add a generic IPI-sending tracepoint, as currently there's no easy way to instrument IPI origins: it's arch dependent and for some major architectures it's not even consistently available. * tag 'smp-core-2023-04-27' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: trace,smp: Trace all smp_function_call*() invocations trace: Add trace_ipi_send_cpu() sched, smp: Trace smp callback causing an IPI smp: reword smp call IPI comment treewide: Trace IPIs sent via smp_send_reschedule() irq_work: Trace self-IPIs sent via arch_irq_work_raise() smp: Trace IPIs sent via arch_send_call_function_ipi_mask() sched, smp: Trace IPIs sent via send_call_function_single_ipi() trace: Add trace_ipi_send_cpumask() kernel/smp: Make csdlock_debug= resettable locking/csd_lock: Remove per-CPU data indirection from CSD lock debugging locking/csd_lock: Remove added data from CSD lock debugging locking/csd_lock: Add Kconfig option for csd_debug default