====================================================== WARNING: possible circular locking dependency detected 6.4.0-rc3-syzkaller-geb0f1697d729 #0 Not tainted ------------------------------------------------------ udevd/5588 is trying to acquire lock: ffff0001fea769a0 (&pgdat->kswapd_wait){-.-.}-{2:2}, at: __wake_up_common_lock kernel/sched/wait.c:137 [inline] ffff0001fea769a0 (&pgdat->kswapd_wait){-.-.}-{2:2}, at: __wake_up+0xec/0x1a8 kernel/sched/wait.c:160 but task is already holding lock: ffff0001b4259b18 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested kernel/sched/core.c:558 [inline] ffff0001b4259b18 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock kernel/sched/sched.h:1366 [inline] ffff0001b4259b18 (&rq->__lock){-.-.}-{2:2}, at: rq_lock kernel/sched/sched.h:1653 [inline] ffff0001b4259b18 (&rq->__lock){-.-.}-{2:2}, at: scheduler_tick+0xa4/0x52c kernel/sched/core.c:5616 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+0x50/0x6c kernel/locking/spinlock.c:378 raw_spin_rq_lock_nested+0x2c/0x44 kernel/sched/core.c:558 raw_spin_rq_lock kernel/sched/sched.h:1366 [inline] rq_lock kernel/sched/sched.h:1653 [inline] task_fork_fair+0x7c/0x23c kernel/sched/fair.c:12095 sched_cgroup_fork+0x38c/0x464 kernel/sched/core.c:4777 copy_process+0x24fc/0x3514 kernel/fork.c:2618 kernel_clone+0x1d8/0x8ac kernel/fork.c:2918 user_mode_thread+0x110/0x178 kernel/fork.c:2996 rest_init+0x2c/0x2f4 init/main.c:700 start_kernel+0x0/0x55c init/main.c:834 start_kernel+0x3f0/0x55c init/main.c:1088 __primary_switched+0xb8/0xc0 arch/arm64/kernel/head.S:523 -> #1 (&p->pi_lock){-.-.}-{2:2}: __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x5c/0x7c kernel/locking/spinlock.c:162 try_to_wake_up+0xb0/0xd9c kernel/sched/core.c:4191 default_wake_function+0x4c/0x60 kernel/sched/core.c:6993 autoremove_wake_function+0x24/0xf8 kernel/sched/wait.c:419 __wake_up_common+0x23c/0x3bc kernel/sched/wait.c:107 __wake_up_common_lock kernel/sched/wait.c:138 [inline] __wake_up+0x10c/0x1a8 kernel/sched/wait.c:160 wakeup_kswapd+0x548/0x8c8 mm/vmscan.c:7798 wake_all_kswapds+0x13c/0x23c mm/page_alloc.c:4028 __alloc_pages_slowpath+0x378/0x1edc mm/page_alloc.c:4296 __alloc_pages+0x3bc/0x698 mm/page_alloc.c:4781 alloc_pages+0x4bc/0x7c0 alloc_slab_page+0xa0/0x164 mm/slub.c:1851 allocate_slab mm/slub.c:2006 [inline] new_slab+0x210/0x2f4 mm/slub.c:2051 ___slab_alloc+0x80c/0xdf4 mm/slub.c:3192 __slab_alloc mm/slub.c:3291 [inline] __slab_alloc_node mm/slub.c:3344 [inline] slab_alloc_node mm/slub.c:3441 [inline] slab_alloc mm/slub.c:3459 [inline] __kmem_cache_alloc_lru mm/slub.c:3466 [inline] kmem_cache_alloc_lru+0x274/0x3b8 mm/slub.c:3482 __d_alloc+0x40/0x6ac fs/dcache.c:1769 d_alloc+0x54/0x18c fs/dcache.c:1849 lookup_one_qstr_excl+0xbc/0x230 fs/namei.c:1601 do_unlinkat+0x2f0/0x830 fs/namei.c:4379 __do_sys_unlinkat fs/namei.c:4436 [inline] __se_sys_unlinkat fs/namei.c:4429 [inline] __arm64_sys_unlinkat+0xcc/0xfc fs/namei.c:4429 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x2c0 arch/arm64/kernel/syscall.c:52 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142 do_el0_svc+0x64/0x198 arch/arm64/kernel/syscall.c:193 el0_svc+0x4c/0x15c arch/arm64/kernel/entry-common.c:637 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655 el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:591 -> #0 (&pgdat->kswapd_wait){-.-.}-{2:2}: check_prev_add kernel/locking/lockdep.c:3108 [inline] check_prevs_add kernel/locking/lockdep.c:3227 [inline] validate_chain kernel/locking/lockdep.c:3842 [inline] __lock_acquire+0x3310/0x75f0 kernel/locking/lockdep.c:5074 lock_acquire+0x23c/0x71c kernel/locking/lockdep.c:5691 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x5c/0x7c kernel/locking/spinlock.c:162 __wake_up_common_lock kernel/sched/wait.c:137 [inline] __wake_up+0xec/0x1a8 kernel/sched/wait.c:160 wakeup_kswapd+0x548/0x8c8 mm/vmscan.c:7798 wake_all_kswapds+0x13c/0x23c mm/page_alloc.c:4028 __alloc_pages_slowpath+0x378/0x1edc mm/page_alloc.c:4296 __alloc_pages+0x3bc/0x698 mm/page_alloc.c:4781 alloc_pages+0x4bc/0x7c0 __stack_depot_save+0x4ac/0x678 lib/stackdepot.c:410 kasan_save_stack+0x54/0x6c mm/kasan/common.c:46 __kasan_record_aux_stack+0xcc/0xe8 mm/kasan/generic.c:491 kasan_record_aux_stack+0x14/0x20 mm/kasan/generic.c:496 task_work_add+0x94/0x3c0 kernel/task_work.c:48 task_tick_mm_cid kernel/sched/core.c:11940 [inline] scheduler_tick+0x2d0/0x52c kernel/sched/core.c:5626 update_process_times+0x198/0x1f4 kernel/time/timer.c:2076 tick_sched_handle kernel/time/tick-sched.c:243 [inline] tick_sched_timer+0x330/0x4e8 kernel/time/tick-sched.c:1481 __run_hrtimer kernel/time/hrtimer.c:1685 [inline] __hrtimer_run_queues+0x458/0xca0 kernel/time/hrtimer.c:1749 hrtimer_interrupt+0x2c0/0xb64 kernel/time/hrtimer.c:1811 timer_handler drivers/clocksource/arm_arch_timer.c:656 [inline] arch_timer_handler_virt+0x74/0x88 drivers/clocksource/arm_arch_timer.c:667 handle_percpu_devid_irq+0x2a4/0x804 kernel/irq/chip.c:930 generic_handle_irq_desc include/linux/irqdesc.h:158 [inline] handle_irq_desc kernel/irq/irqdesc.c:651 [inline] generic_handle_domain_irq+0x7c/0xc4 kernel/irq/irqdesc.c:707 __gic_handle_irq drivers/irqchip/irq-gic-v3.c:728 [inline] __gic_handle_irq_from_irqson drivers/irqchip/irq-gic-v3.c:779 [inline] gic_handle_irq+0x70/0x1e4 drivers/irqchip/irq-gic-v3.c:823 call_on_irq_stack+0x24/0x4c arch/arm64/kernel/entry.S:882 do_interrupt_handler+0xd4/0x138 arch/arm64/kernel/entry-common.c:274 __el1_irq arch/arm64/kernel/entry-common.c:471 [inline] el1_interrupt+0x34/0x68 arch/arm64/kernel/entry-common.c:486 el1h_64_irq_handler+0x18/0x24 arch/arm64/kernel/entry-common.c:491 el1h_64_irq+0x64/0x68 arch/arm64/kernel/entry.S:587 __percpu_read_32 arch/arm64/include/asm/percpu.h:125 [inline] lockdep_enabled kernel/locking/lockdep.c:119 [inline] lock_acquire+0x174/0x71c kernel/locking/lockdep.c:5667 __mnt_want_write+0x12c/0x4c4 fs/namespace.c:348 mnt_want_write+0x4c/0x9c fs/namespace.c:395 do_unlinkat+0x1b0/0x830 fs/namei.c:4374 __do_sys_unlinkat fs/namei.c:4436 [inline] __se_sys_unlinkat fs/namei.c:4429 [inline] __arm64_sys_unlinkat+0xcc/0xfc fs/namei.c:4429 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x2c0 arch/arm64/kernel/syscall.c:52 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142 do_el0_svc+0x64/0x198 arch/arm64/kernel/syscall.c:193 el0_svc+0x4c/0x15c arch/arm64/kernel/entry-common.c:637 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655 el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:591 other info that might help us debug this: Chain exists of: &pgdat->kswapd_wait --> &p->pi_lock --> &rq->__lock Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&rq->__lock); lock(&p->pi_lock); lock(&rq->__lock); lock(&pgdat->kswapd_wait); *** DEADLOCK *** 2 locks held by udevd/5588: #0: ffff0000db6f8460 (sb_writers#5){.+.+}-{0:0}, at: mnt_want_write+0x44/0x9c fs/namespace.c:394 #1: ffff0001b4259b18 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested kernel/sched/core.c:558 [inline] #1: ffff0001b4259b18 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock kernel/sched/sched.h:1366 [inline] #1: ffff0001b4259b18 (&rq->__lock){-.-.}-{2:2}, at: rq_lock kernel/sched/sched.h:1653 [inline] #1: ffff0001b4259b18 (&rq->__lock){-.-.}-{2:2}, at: scheduler_tick+0xa4/0x52c kernel/sched/core.c:5616 stack backtrace: CPU: 1 PID: 5588 Comm: udevd Not tainted 6.4.0-rc3-syzkaller-geb0f1697d729 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/28/2023 Call trace: dump_backtrace+0x1b8/0x1e4 arch/arm64/kernel/stacktrace.c:233 show_stack+0x2c/0x44 arch/arm64/kernel/stacktrace.c:240 __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xd0/0x124 lib/dump_stack.c:106 dump_stack+0x1c/0x28 lib/dump_stack.c:113 print_circular_bug+0x150/0x1b8 kernel/locking/lockdep.c:2066 check_noncircular+0x2cc/0x378 kernel/locking/lockdep.c:2188 check_prev_add kernel/locking/lockdep.c:3108 [inline] check_prevs_add kernel/locking/lockdep.c:3227 [inline] validate_chain kernel/locking/lockdep.c:3842 [inline] __lock_acquire+0x3310/0x75f0 kernel/locking/lockdep.c:5074 lock_acquire+0x23c/0x71c kernel/locking/lockdep.c:5691 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x5c/0x7c kernel/locking/spinlock.c:162 __wake_up_common_lock kernel/sched/wait.c:137 [inline] __wake_up+0xec/0x1a8 kernel/sched/wait.c:160 wakeup_kswapd+0x548/0x8c8 mm/vmscan.c:7798 wake_all_kswapds+0x13c/0x23c mm/page_alloc.c:4028 __alloc_pages_slowpath+0x378/0x1edc mm/page_alloc.c:4296 __alloc_pages+0x3bc/0x698 mm/page_alloc.c:4781 alloc_pages+0x4bc/0x7c0 __stack_depot_save+0x4ac/0x678 lib/stackdepot.c:410 kasan_save_stack+0x54/0x6c mm/kasan/common.c:46 __kasan_record_aux_stack+0xcc/0xe8 mm/kasan/generic.c:491 kasan_record_aux_stack+0x14/0x20 mm/kasan/generic.c:496 task_work_add+0x94/0x3c0 kernel/task_work.c:48 task_tick_mm_cid kernel/sched/core.c:11940 [inline] scheduler_tick+0x2d0/0x52c kernel/sched/core.c:5626 update_process_times+0x198/0x1f4 kernel/time/timer.c:2076 tick_sched_handle kernel/time/tick-sched.c:243 [inline] tick_sched_timer+0x330/0x4e8 kernel/time/tick-sched.c:1481 __run_hrtimer kernel/time/hrtimer.c:1685 [inline] __hrtimer_run_queues+0x458/0xca0 kernel/time/hrtimer.c:1749 hrtimer_interrupt+0x2c0/0xb64 kernel/time/hrtimer.c:1811 timer_handler drivers/clocksource/arm_arch_timer.c:656 [inline] arch_timer_handler_virt+0x74/0x88 drivers/clocksource/arm_arch_timer.c:667 handle_percpu_devid_irq+0x2a4/0x804 kernel/irq/chip.c:930 generic_handle_irq_desc include/linux/irqdesc.h:158 [inline] handle_irq_desc kernel/irq/irqdesc.c:651 [inline] generic_handle_domain_irq+0x7c/0xc4 kernel/irq/irqdesc.c:707 __gic_handle_irq drivers/irqchip/irq-gic-v3.c:728 [inline] __gic_handle_irq_from_irqson drivers/irqchip/irq-gic-v3.c:779 [inline] gic_handle_irq+0x70/0x1e4 drivers/irqchip/irq-gic-v3.c:823 call_on_irq_stack+0x24/0x4c arch/arm64/kernel/entry.S:882 do_interrupt_handler+0xd4/0x138 arch/arm64/kernel/entry-common.c:274 __el1_irq arch/arm64/kernel/entry-common.c:471 [inline] el1_interrupt+0x34/0x68 arch/arm64/kernel/entry-common.c:486 el1h_64_irq_handler+0x18/0x24 arch/arm64/kernel/entry-common.c:491 el1h_64_irq+0x64/0x68 arch/arm64/kernel/entry.S:587 __percpu_read_32 arch/arm64/include/asm/percpu.h:125 [inline] lockdep_enabled kernel/locking/lockdep.c:119 [inline] lock_acquire+0x174/0x71c kernel/locking/lockdep.c:5667 __mnt_want_write+0x12c/0x4c4 fs/namespace.c:348 mnt_want_write+0x4c/0x9c fs/namespace.c:395 do_unlinkat+0x1b0/0x830 fs/namei.c:4374 __do_sys_unlinkat fs/namei.c:4436 [inline] __se_sys_unlinkat fs/namei.c:4429 [inline] __arm64_sys_unlinkat+0xcc/0xfc fs/namei.c:4429 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x2c0 arch/arm64/kernel/syscall.c:52 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142 do_el0_svc+0x64/0x198 arch/arm64/kernel/syscall.c:193 el0_svc+0x4c/0x15c arch/arm64/kernel/entry-common.c:637 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655 el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:591