rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: 1-...!: (1 GPs behind) idle=4a34/1/0x4000000000000000 softirq=16360/16361 fqs=2 rcu: (detected by 0, t=10506 jiffies, g=12005, q=652 ncpus=2) Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 UID: 0 PID: 5852 Comm: udevd Not tainted 6.13.0-rc3-next-20241220-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024 RIP: 0010:_test_bit include/asm-generic/bitops/instrumented-non-atomic.h:141 [inline] RIP: 0010:hlock_class kernel/locking/lockdep.c:228 [inline] RIP: 0010:mark_lock+0x88/0x360 kernel/locking/lockdep.c:4727 Code: 41 d3 e6 49 8d 5f 20 48 89 d8 48 c1 e8 03 42 0f b6 04 28 84 c0 0f 85 3a 02 00 00 8b 1b 81 e3 ff 1f 00 00 48 89 d8 48 c1 e8 06 <48> 8d 3c c5 40 78 2d 94 be 08 00 00 00 e8 a6 9e 8a 00 48 0f a3 1d RSP: 0018:ffffc90000a188a8 EFLAGS: 00000046 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 RDX: 0000000000000000 RSI: ffff888062e82938 RDI: ffff888062e81e00 RBP: 0000000000000000 R08: ffffffff942d784f R09: 1ffffffff285af09 R10: dffffc0000000000 R11: fffffbfff285af0a R12: ffff888062e828cc R13: dffffc0000000000 R14: 0000000000000001 R15: ffff888062e82938 FS: 00007fe731fb6c80(0000) GS:ffff8880b8700000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000000110c3bc412 CR3: 0000000062e3e000 CR4: 00000000003526f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: mark_usage kernel/locking/lockdep.c:4635 [inline] __lock_acquire+0xbc3/0x2100 kernel/locking/lockdep.c:5180 lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5849 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0xd5/0x120 kernel/locking/spinlock.c:162 debug_object_activate+0x17f/0x580 lib/debugobjects.c:818 debug_hrtimer_activate kernel/time/hrtimer.c:428 [inline] debug_activate kernel/time/hrtimer.c:469 [inline] enqueue_hrtimer+0x30/0x3c0 kernel/time/hrtimer.c:1076 __run_hrtimer kernel/time/hrtimer.c:1756 [inline] __hrtimer_run_queues+0x6cb/0xd30 kernel/time/hrtimer.c:1803 hrtimer_interrupt+0x403/0xa40 kernel/time/hrtimer.c:1865 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1038 [inline] __sysvec_apic_timer_interrupt+0x110/0x420 arch/x86/kernel/apic/apic.c:1055 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1049 [inline] sysvec_apic_timer_interrupt+0xa1/0xc0 arch/x86/kernel/apic/apic.c:1049 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702 RIP: 0010:lock_acquire+0x264/0x550 kernel/locking/lockdep.c:5853 Code: 2b 00 74 08 4c 89 f7 e8 0a 13 8b 00 f6 44 24 61 02 0f 85 85 01 00 00 41 f7 c7 00 02 00 00 74 01 fb 48 c7 44 24 40 0e 36 e0 45 <4b> c7 44 25 00 00 00 00 00 43 c7 44 25 09 00 00 00 00 43 c7 44 25 RSP: 0018:ffffc90003defb60 EFLAGS: 00000206 RAX: 0000000000000001 RBX: 1ffff920007bdf78 RCX: ffff888062e828e0 RDX: dffffc0000000000 RSI: ffffffff8c0aaba0 RDI: ffffffff8c5fed00 RBP: ffffc90003defca8 R08: ffffffff942d7877 R09: 1ffffffff285af0e R10: dffffc0000000000 R11: fffffbfff285af0f R12: 1ffff920007bdf74 R13: dffffc0000000000 R14: ffffc90003defbc0 R15: 0000000000000246 __might_fault+0xc6/0x120 mm/memory.c:6841 _inline_copy_to_user include/linux/uaccess.h:192 [inline] _copy_to_user+0x2c/0xb0 lib/usercopy.c:26 copy_to_user include/linux/uaccess.h:225 [inline] readlink_copy fs/namei.c:5282 [inline] vfs_readlink+0x1df/0x550 fs/namei.c:5305 do_readlinkat+0x249/0x3a0 fs/stat.c:576 __do_sys_readlink fs/stat.c:599 [inline] __se_sys_readlink fs/stat.c:596 [inline] __x64_sys_readlink+0x7f/0x90 fs/stat.c:596 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fe731b17d47 Code: 73 01 c3 48 8b 0d e1 90 0d 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 b8 59 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d b1 90 0d 00 f7 d8 64 89 01 48 RSP: 002b:00007ffe80c83118 EFLAGS: 00000246 ORIG_RAX: 0000000000000059 RAX: ffffffffffffffda RBX: 00007ffe80c831b8 RCX: 00007fe731b17d47 RDX: 0000000000000400 RSI: 00007ffe80c835b8 RDI: 00007ffe80c83ad8 RBP: 00007ffe80c83ad8 R08: 0000000000000000 R09: 00007ffe80c83398 R10: 0000000000000100 R11: 0000000000000246 R12: 00007ffe80c835b8 R13: 000056339bd4f330 R14: 000056339bd45e50 R15: 00007ffe80c83ae6 rcu: rcu_preempt kthread starved for 10495 jiffies! g12005 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=0 rcu: Unless rcu_preempt kthread gets sufficient CPU time, OOM is now expected behavior. rcu: RCU grace-period kthread stack dump: task:rcu_preempt state:R running task stack:25912 pid:17 tgid:17 ppid:2 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:5371 [inline] __schedule+0x189f/0x4c80 kernel/sched/core.c:6758 __schedule_loop kernel/sched/core.c:6835 [inline] schedule+0x14b/0x320 kernel/sched/core.c:6850 schedule_timeout+0x15a/0x290 kernel/time/sleep_timeout.c:99 rcu_gp_fqs_loop+0x2df/0x1330 kernel/rcu/tree.c:2024 rcu_gp_kthread+0xa7/0x3b0 kernel/rcu/tree.c:2226 kthread+0x7a9/0x920 kernel/kthread.c:464 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:148 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244 rcu: Stack dump where RCU GP kthread last ran: CPU: 0 UID: 0 PID: 6589 Comm: syz.5.98 Not tainted 6.13.0-rc3-next-20241220-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024 RIP: 0010:get_current arch/x86/include/asm/current.h:49 [inline] RIP: 0010:__sanitizer_cov_trace_pc+0x8/0x70 kernel/kcov.c:216 Code: 8b 3d 44 af 70 0c 48 89 de 5b e9 73 08 5b 00 0f 1f 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 48 8b 04 24 <65> 48 8b 0c 25 c0 d6 03 00 65 8b 15 90 b2 44 7e 81 e2 00 01 ff 00 RSP: 0018:ffffc90002fb73f8 EFLAGS: 00000202 RAX: ffffffff81b33f35 RBX: 1ffff110170e8901 RCX: ffff88802c2e8000 RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000 RBP: ffffc90002fb7600 R08: ffffffff81b33f00 R09: 1ffffffff285af0e R10: dffffc0000000000 R11: fffffbfff285af0f R12: ffff8880b863fb88 R13: ffff8880b8744808 R14: ffff8880b863fb80 R15: 0000000000000001 FS: 0000000000000000(0000) GS:ffff8880b8600000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f08bc0de000 CR3: 00000000699ee000 CR4: 00000000003526f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: csd_lock_wait kernel/smp.c:340 [inline] smp_call_function_many_cond+0x1bc5/0x2d30 kernel/smp.c:885 on_each_cpu_cond_mask+0x3f/0x80 kernel/smp.c:1052 __flush_tlb_multi arch/x86/include/asm/paravirt.h:91 [inline] flush_tlb_multi arch/x86/mm/tlb.c:966 [inline] flush_tlb_mm_range+0x42d/0x710 arch/x86/mm/tlb.c:1054 tlb_flush arch/x86/include/asm/tlb.h:20 [inline] tlb_flush_mmu_tlbonly include/asm-generic/tlb.h:465 [inline] tlb_flush_mmu+0x1aa/0x680 mm/mmu_gather.c:379 tlb_finish_mmu+0xd4/0x200 mm/mmu_gather.c:472 exit_mmap+0x52f/0xd50 mm/mmap.c:1357 __mmput+0x115/0x420 kernel/fork.c:1345 exit_mm+0x220/0x310 kernel/exit.c:570 do_exit+0x9b2/0x28e0 kernel/exit.c:925 do_group_exit+0x207/0x2c0 kernel/exit.c:1087 get_signal+0x16b2/0x1750 kernel/signal.c:3017 arch_do_signal_or_restart+0x96/0x860 arch/x86/kernel/signal.c:337 exit_to_user_mode_loop kernel/entry/common.c:111 [inline] exit_to_user_mode_prepare include/linux/entry-common.h:329 [inline] __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline] syscall_exit_to_user_mode+0xce/0x340 kernel/entry/common.c:218 do_syscall_64+0x100/0x230 arch/x86/entry/common.c:89 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f4a81985d29 Code: Unable to access opcode bytes at 0x7f4a81985cff. RSP: 002b:00007f4a826d20e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca RAX: fffffffffffffe00 RBX: 00007f4a81b76088 RCX: 00007f4a81985d29 RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007f4a81b76088 RBP: 00007f4a81b76080 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f4a81b7608c R13: 0000000000000000 R14: 00007ffc27897f50 R15: 00007ffc27898038