sched: DL replenish lagged too much rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: 1-...!: (2 GPs behind) idle=3df4/1/0x4000000000000000 softirq=15936/15942 fqs=2 rcu: (detected by 0, t=10502 jiffies, g=12957, q=453 ncpus=2) Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 UID: 0 PID: 5199 Comm: udevd Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025 RIP: 0010:lockdep_recursion_finish kernel/locking/lockdep.c:470 [inline] RIP: 0010:lock_acquire+0x130/0x360 kernel/locking/lockdep.c:5870 Code: 8b 54 24 04 44 89 e1 45 89 f0 6a 00 6a 00 6a 00 55 ff 74 24 30 e8 e0 02 00 00 48 83 c4 28 48 c7 c7 ab 15 9d 8d e8 a0 79 ae 09 ff ff ff ff 65 0f c1 05 73 6d f4 10 83 f8 01 0f 85 c9 00 00 00 RSP: 0018:ffffc90000a08b60 EFLAGS: 00000082 RAX: 0000000000000001 RBX: 0000000000000000 RCX: 61cef5f40a1a2900 RDX: 0000000000000000 RSI: ffffffff8d9d15ab RDI: ffffffff8bc074e0 RBP: ffffffff84993a3a R08: 0000000000000000 R09: ffffffff84993a3a R10: ffffc90000a08cb0 R11: fffff52000141198 R12: 0000000000000000 R13: ffffffff99c44200 R14: 0000000000000001 R15: 0000000000000046 FS: 00007f6591f3d880(0000) GS:ffff888125e0f000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000055559391e5c8 CR3: 00000000617e4000 CR4: 00000000003526f0 Call Trace: __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0xa7/0xf0 kernel/locking/spinlock.c:162 debug_object_deactivate+0x9a/0x250 lib/debugobjects.c:873 debug_hrtimer_deactivate kernel/time/hrtimer.c:443 [inline] debug_deactivate+0x1d/0x200 kernel/time/hrtimer.c:483 __run_hrtimer kernel/time/hrtimer.c:1745 [inline] __hrtimer_run_queues+0x2b0/0xc60 kernel/time/hrtimer.c:1841 hrtimer_interrupt+0x45b/0xaa0 kernel/time/hrtimer.c:1903 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1041 [inline] __sysvec_apic_timer_interrupt+0x108/0x410 arch/x86/kernel/apic/apic.c:1058 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1052 [inline] sysvec_apic_timer_interrupt+0xa1/0xc0 arch/x86/kernel/apic/apic.c:1052 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702 RIP: 0010:rcu_read_unlock include/linux/rcupdate.h:895 [inline] RIP: 0010:class_rcu_destructor include/linux/rcupdate.h:1195 [inline] RIP: 0010:kernfs_root+0x145/0x230 fs/kernfs/kernfs-internal.h:80 Code: 78 4c 89 f0 48 c1 e8 03 42 80 3c 20 00 74 08 4c 89 f7 e8 de 4d c5 ff 4d 8b 36 e8 a6 64 eb 08 89 c5 31 ff 89 c6 e8 db b3 5f ff <85> ed 74 10 e8 72 f9 45 ff 84 c0 74 0e e8 89 af 5f ff eb 7d e8 82 RSP: 0018:ffffc900031d79e8 EFLAGS: 00000293 RAX: ffffffff825fe465 RBX: ffffffff825fe33c RCX: 0000000000000000 RDX: ffff888061451e40 RSI: 0000000000000001 RDI: 0000000000000000 RBP: 0000000000000001 R08: 0000000000000000 R09: ffffffff825fe33c R10: dffffc0000000000 R11: ffffed10039db801 R12: dffffc0000000000 R13: 0000000000000001 R14: ffff88801ae88000 R15: ffff88801beea000 kernfs_root_is_locked fs/kernfs/kernfs-internal.h:109 [inline] kernfs_rcu_name fs/kernfs/kernfs-internal.h:119 [inline] kernfs_dop_revalidate+0x365/0x5d0 fs/kernfs/dir.c:1192 d_revalidate fs/namei.c:929 [inline] lookup_fast+0x253/0x5b0 fs/namei.c:-1 walk_component fs/namei.c:2147 [inline] link_path_walk+0x642/0xea0 fs/namei.c:2519 path_lookupat+0x97/0x430 fs/namei.c:2675 filename_lookup+0x212/0x570 fs/namei.c:2705 do_readlinkat+0xd9/0x500 fs/stat.c:576 __do_sys_readlink fs/stat.c:613 [inline] __se_sys_readlink fs/stat.c:610 [inline] __x64_sys_readlink+0x7f/0x90 fs/stat.c:610 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f65919153a7 Code: 00 00 90 48 83 ec 10 48 63 ff 45 31 c9 45 31 c0 6a 00 31 c9 e8 8a 20 f9 ff 48 83 c4 18 c3 0f 1f 44 00 00 b8 59 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 01 c3 48 8b 15 21 ba 0d 00 f7 d8 64 89 02 48 RSP: 002b:00007ffcf41f5f28 EFLAGS: 00000246 ORIG_RAX: 0000000000000059 RAX: ffffffffffffffda RBX: 00007ffcf41f6400 RCX: 00007f65919153a7 RDX: 0000000000000400 RSI: 00007ffcf41f5f30 RDI: 00007ffcf41f6400 RBP: 00007ffcf41f5f30 R08: 000055a302bcb974 R09: 0000000000000001 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000400 R13: 00000000000000fe R14: 000055a2d0adbbe0 R15: 00007ffcf41f6f00 rcu: rcu_preempt kthread starved for 10494 jiffies! g12957 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:27224 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5325 [inline] __schedule+0x1798/0x4cc0 kernel/sched/core.c:6929 __schedule_loop kernel/sched/core.c:7011 [inline] schedule+0x165/0x360 kernel/sched/core.c:7026 schedule_timeout+0x12b/0x270 kernel/time/sleep_timeout.c:99 rcu_gp_fqs_loop+0x301/0x1540 kernel/rcu/tree.c:2083 rcu_gp_kthread+0x99/0x390 kernel/rcu/tree.c:2285 kthread+0x711/0x8a0 kernel/kthread.c:463 ret_from_fork+0x4bc/0x870 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 rcu: Stack dump where RCU GP kthread last ran: CPU: 0 UID: 0 PID: 5494 Comm: dhcpcd Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025 RIP: 0010:csd_lock_wait kernel/smp.c:342 [inline] RIP: 0010:smp_call_function_many_cond+0xd33/0x12d0 kernel/smp.c:877 Code: 45 8b 2c 24 44 89 ee 83 e6 01 31 ff e8 96 73 0b 00 41 83 e5 01 49 bd 00 00 00 00 00 fc ff df 75 07 e8 41 6f 0b 00 eb 38 f3 90 <42> 0f b6 04 2b 84 c0 75 11 41 f7 04 24 01 00 00 00 74 1e e8 25 6f RSP: 0018:ffffc90003517540 EFLAGS: 00000293 RAX: ffffffff81b424db RBX: 1ffff110170e7ffd RCX: ffff88802c538000 RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000 RBP: ffffc900035176c0 R08: ffffffff8f9e0f77 R09: 1ffffffff1f3c1ee R10: dffffc0000000000 R11: fffffbfff1f3c1ef R12: ffff8880b873ffe8 R13: dffffc0000000000 R14: ffff8880b863b240 R15: 0000000000000001 FS: 00007f17520fa740(0000) GS:ffff888125d0f000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f71cfbb3ad8 CR3: 000000006bffe000 CR4: 00000000003526f0 Call Trace: on_each_cpu_cond_mask+0x3f/0x80 kernel/smp.c:1043 __flush_tlb_multi arch/x86/include/asm/paravirt.h:91 [inline] flush_tlb_multi arch/x86/mm/tlb.c:1361 [inline] flush_tlb_mm_range+0x6b1/0x12d0 arch/x86/mm/tlb.c:1451 dup_mmap+0x1594/0x1b10 mm/mmap.c:1873 dup_mm kernel/fork.c:1489 [inline] copy_mm+0x13c/0x4b0 kernel/fork.c:1541 copy_process+0x1706/0x3c00 kernel/fork.c:2181 kernel_clone+0x21e/0x840 kernel/fork.c:2609 __do_sys_clone kernel/fork.c:2750 [inline] __se_sys_clone kernel/fork.c:2734 [inline] __x64_sys_clone+0x18b/0x1e0 kernel/fork.c:2734 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f17521ce636 Code: 89 df e8 6d e8 f6 ff 45 31 c0 31 d2 31 f6 64 48 8b 04 25 10 00 00 00 bf 11 00 20 01 4c 8d 90 d0 02 00 00 b8 38 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 52 89 c5 85 c0 75 31 64 48 8b 04 25 10 00 00 RSP: 002b:00007ffe6199f740 EFLAGS: 00000246 ORIG_RAX: 0000000000000038 RAX: ffffffffffffffda RBX: 00007ffe6199f748 RCX: 00007f17521ce636 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000001200011 RBP: 00007ffe619bfc90 R08: 0000000000000000 R09: 0000000000000001 R10: 00007f17520faa10 R11: 0000000000000246 R12: 00007ffe6199f880 R13: 0000000000000000 R14: 0000000000000000 R15: 0000562fe31cbac0