EEVDF scheduling fail, picking leftmost ====================================================== WARNING: possible circular locking dependency detected 6.6.0-rc6-syzkaller-00169-gc70793fb7632 #0 Not tainted ------------------------------------------------------ udevd/5312 is trying to acquire lock: ffffffff87e9a4f8 ((console_sem).lock){-.-.}-{2:2}, at: down_trylock+0x12/0x70 kernel/locking/semaphore.c:139 but task is already holding lock: ffff8881f673b558 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested kernel/sched/core.c:558 [inline] ffff8881f673b558 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock kernel/sched/sched.h:1372 [inline] ffff8881f673b558 (&rq->__lock){-.-.}-{2:2}, at: rq_lock kernel/sched/sched.h:1681 [inline] ffff8881f673b558 (&rq->__lock){-.-.}-{2:2}, at: __schedule+0x290/0x30a0 kernel/sched/core.c:6612 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (&rq->__lock){-.-.}-{2:2}: _raw_spin_lock_nested+0x31/0x40 kernel/locking/spinlock.c:378 raw_spin_rq_lock_nested+0x1f/0x30 kernel/sched/core.c:558 raw_spin_rq_lock kernel/sched/sched.h:1372 [inline] rq_lock kernel/sched/sched.h:1681 [inline] task_fork_fair+0x72/0x140 kernel/sched/fair.c:12416 sched_cgroup_fork+0x3cf/0x510 kernel/sched/core.c:4816 copy_process+0x4b57/0x72f0 kernel/fork.c:2609 kernel_clone+0xfc/0x850 kernel/fork.c:2909 user_mode_thread+0xb4/0xf0 kernel/fork.c:2987 rest_init+0x27/0x2b0 init/main.c:691 arch_call_rest_init+0x13/0x30 init/main.c:823 start_kernel+0x39a/0x470 init/main.c:1068 x86_64_start_reservations+0x18/0x30 arch/x86/kernel/head64.c:556 x86_64_start_kernel+0xb2/0xc0 arch/x86/kernel/head64.c:537 secondary_startup_64_no_verify+0x166/0x16b -> #1 (&p->pi_lock){-.-.}-{2:2}: __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x3a/0x50 kernel/locking/spinlock.c:162 class_raw_spinlock_irqsave_constructor include/linux/spinlock.h:518 [inline] try_to_wake_up+0xaa/0x1230 kernel/sched/core.c:4230 up+0x79/0xb0 kernel/locking/semaphore.c:191 __up_console_sem kernel/printk/printk.c:346 [inline] __console_unlock kernel/printk/printk.c:2718 [inline] console_unlock+0x1cf/0x260 kernel/printk/printk.c:3037 vprintk_emit+0x17f/0x5f0 kernel/printk/printk.c:2307 dev_vprintk_emit drivers/base/core.c:4849 [inline] dev_printk_emit+0xfb/0x140 drivers/base/core.c:4860 __dev_printk+0xf5/0x270 drivers/base/core.c:4872 _dev_info+0xe5/0x120 drivers/base/core.c:4918 show_string drivers/usb/core/hub.c:2313 [inline] show_string drivers/usb/core/hub.c:2309 [inline] announce_device drivers/usb/core/hub.c:2331 [inline] usb_new_device+0x975/0x19f0 drivers/usb/core/hub.c:2580 hub_port_connect drivers/usb/core/hub.c:5463 [inline] hub_port_connect_change drivers/usb/core/hub.c:5603 [inline] port_event drivers/usb/core/hub.c:5763 [inline] hub_event+0x2e62/0x4f40 drivers/usb/core/hub.c:5845 process_one_work+0x884/0x15c0 kernel/workqueue.c:2630 process_scheduled_works kernel/workqueue.c:2703 [inline] worker_thread+0x8b9/0x1290 kernel/workqueue.c:2784 kthread+0x33c/0x440 kernel/kthread.c:388 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:304 -> #0 ((console_sem).lock){-.-.}-{2:2}: check_prev_add kernel/locking/lockdep.c:3134 [inline] check_prevs_add kernel/locking/lockdep.c:3253 [inline] validate_chain kernel/locking/lockdep.c:3868 [inline] __lock_acquire+0x2e3d/0x5de0 kernel/locking/lockdep.c:5136 lock_acquire kernel/locking/lockdep.c:5753 [inline] lock_acquire+0x1ae/0x510 kernel/locking/lockdep.c:5718 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x3a/0x50 kernel/locking/spinlock.c:162 down_trylock+0x12/0x70 kernel/locking/semaphore.c:139 __down_trylock_console_sem+0x40/0x140 kernel/printk/printk.c:329 console_trylock+0x73/0x130 kernel/printk/printk.c:2671 console_trylock_spinning kernel/printk/printk.c:1927 [inline] vprintk_emit+0x162/0x5f0 kernel/printk/printk.c:2306 vprintk+0x7b/0x90 kernel/printk/printk_safe.c:45 _printk+0xc8/0x100 kernel/printk/printk.c:2332 pick_eevdf kernel/sched/fair.c:976 [inline] pick_next_entity kernel/sched/fair.c:5278 [inline] pick_next_task_fair+0x4e0/0x1010 kernel/sched/fair.c:8222 __pick_next_task kernel/sched/core.c:6004 [inline] pick_next_task kernel/sched/core.c:6514 [inline] __schedule+0x3fd/0x30a0 kernel/sched/core.c:6659 schedule+0xe7/0x1b0 kernel/sched/core.c:6771 exit_to_user_mode_loop kernel/entry/common.c:159 [inline] exit_to_user_mode_prepare+0xbb/0x1f0 kernel/entry/common.c:204 irqentry_exit_to_user_mode+0x9/0x40 kernel/entry/common.c:309 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:645 other info that might help us debug this: Chain exists of: (console_sem).lock --> &p->pi_lock --> &rq->__lock Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&rq->__lock); lock(&p->pi_lock); lock(&rq->__lock); lock((console_sem).lock); *** DEADLOCK *** 1 lock held by udevd/5312: #0: ffff8881f673b558 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested kernel/sched/core.c:558 [inline] #0: ffff8881f673b558 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock kernel/sched/sched.h:1372 [inline] #0: ffff8881f673b558 (&rq->__lock){-.-.}-{2:2}, at: rq_lock kernel/sched/sched.h:1681 [inline] #0: ffff8881f673b558 (&rq->__lock){-.-.}-{2:2}, at: __schedule+0x290/0x30a0 kernel/sched/core.c:6612 stack backtrace: CPU: 1 PID: 5312 Comm: udevd Not tainted 6.6.0-rc6-syzkaller-00169-gc70793fb7632 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/09/2023 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xd9/0x1b0 lib/dump_stack.c:106 check_noncircular+0x311/0x3f0 kernel/locking/lockdep.c:2187 check_prev_add kernel/locking/lockdep.c:3134 [inline] check_prevs_add kernel/locking/lockdep.c:3253 [inline] validate_chain kernel/locking/lockdep.c:3868 [inline] __lock_acquire+0x2e3d/0x5de0 kernel/locking/lockdep.c:5136 lock_acquire kernel/locking/lockdep.c:5753 [inline] lock_acquire+0x1ae/0x510 kernel/locking/lockdep.c:5718 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x3a/0x50 kernel/locking/spinlock.c:162 down_trylock+0x12/0x70 kernel/locking/semaphore.c:139 __down_trylock_console_sem+0x40/0x140 kernel/printk/printk.c:329 console_trylock+0x73/0x130 kernel/printk/printk.c:2671 console_trylock_spinning kernel/printk/printk.c:1927 [inline] vprintk_emit+0x162/0x5f0 kernel/printk/printk.c:2306 vprintk+0x7b/0x90 kernel/printk/printk_safe.c:45 _printk+0xc8/0x100 kernel/printk/printk.c:2332 pick_eevdf kernel/sched/fair.c:976 [inline] pick_next_entity kernel/sched/fair.c:5278 [inline] pick_next_task_fair+0x4e0/0x1010 kernel/sched/fair.c:8222 __pick_next_task kernel/sched/core.c:6004 [inline] pick_next_task kernel/sched/core.c:6514 [inline] __schedule+0x3fd/0x30a0 kernel/sched/core.c:6659 schedule+0xe7/0x1b0 kernel/sched/core.c:6771 exit_to_user_mode_loop kernel/entry/common.c:159 [inline] exit_to_user_mode_prepare+0xbb/0x1f0 kernel/entry/common.c:204 irqentry_exit_to_user_mode+0x9/0x40 kernel/entry/common.c:309 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:645 RIP: 0033:0x563bba861099 Code: ef e8 eb e5 ff ff 48 85 c0 75 14 48 8d 35 07 df 00 00 48 89 ef e8 d7 e5 ff ff 48 85 c0 74 0b 4c 89 ee 4c 89 e7 e8 cc fe ff ff <4d> 8b 64 24 48 48 8b 84 24 08 02 00 00 64 48 2b 04 25 28 00 00 00 RSP: 002b:00007ffdb6114770 EFLAGS: 00000202 RAX: 0000000000000000 RBX: 00000000000000ff RCX: 0000000000000000 RDX: 0000000000000000 RSI: 00007ffdb6114a28 RDI: 0000563bbaf65e10 RBP: 0000563bbaf65e10 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000010 R11: 0000000000000000 R12: 0000563bbaf65e10 R13: 0000563bbaf65e10 R14: 0000000000000000 R15: 00007ffdb6114e39