rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: 0-...!: (1 GPs behind) idle=c284/1/0x4000000000000000 softirq=69168/69172 fqs=0 rcu: (detected by 1, t=10502 jiffies, g=56737, q=1189 ncpus=2) Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 UID: 101 PID: 5273 Comm: dhcpcd Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026 RIP: 0010:match_held_lock+0x1/0xb0 kernel/locking/lockdep.c:5305 Code: 2b 8e e8 d2 3b 67 f5 e8 9d ed b9 f5 e8 78 22 2e f6 90 31 db eb b6 0f 1f 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 53 <48> 89 fb 48 39 77 10 74 72 66 83 7f 22 1f 76 63 48 8b 46 08 48 89 RSP: 0018:ffffc90000007d98 EFLAGS: 00000046 RAX: 0000000000000003 RBX: ffff888075aad2c0 RCX: 0000000000000001 RDX: 0000000000000000 RSI: ffff888075aad2c0 RDI: ffff8880273db0e0 RBP: ffff8880273da540 R08: 0000000000000005 R09: 0000000000000000 R10: 0000000000000001 R11: 0000000000000000 R12: 00000000ffffffff R13: 0000000000000046 R14: ffff8880273db0e0 R15: 0000000000000000 FS: 00007f459fc6e780(0000) GS:ffff888123ddc000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fb136d5da08 CR3: 000000007a0e1000 CR4: 00000000003526f0 Call Trace: __lock_is_held kernel/locking/lockdep.c:5601 [inline] lock_is_held_type+0x9d/0x140 kernel/locking/lockdep.c:5940 lock_is_held include/linux/lockdep.h:249 [inline] advance_sched+0x838/0xd20 net/sched/sch_taprio.c:933 __run_hrtimer kernel/time/hrtimer.c:2032 [inline] __hrtimer_run_queues+0x462/0x9c0 kernel/time/hrtimer.c:2096 hrtimer_interrupt+0x3e5/0x940 kernel/time/hrtimer.c:2215 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1051 [inline] __sysvec_apic_timer_interrupt+0x109/0x470 arch/x86/kernel/apic/apic.c:1068 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1062 [inline] sysvec_apic_timer_interrupt+0x9e/0xc0 arch/x86/kernel/apic/apic.c:1062 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674 RIP: 0010:lock_acquire+0x5e/0x370 kernel/locking/lockdep.c:5872 Code: 05 fb 4d 7e 12 83 f8 07 0f 87 da 00 00 00 48 0f a3 05 86 85 3c 0f 0f 82 ac 02 00 00 8b 35 4e b9 3c 0f 85 f6 0f 85 c7 00 00 00 <48> 8b 44 24 30 65 48 2b 05 9d 4d 7e 12 0f 85 ec 02 00 00 48 83 c4 RSP: 0018:ffffc90004a47630 EFLAGS: 00000206 RAX: 0000000000000046 RBX: 0000000000000000 RCX: 0000000000000000 RDX: 0000000000000000 RSI: ffffffff8e17fc5f RDI: ffffffff8c401580 RBP: ffffffff8ebe8180 R08: 000000006db591ba R09: 0000000000000007 R10: 0000000000000200 R11: 0000000000000000 R12: 0000000000000002 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 rcu_lock_acquire include/linux/rcupdate.h:300 [inline] rcu_read_lock include/linux/rcupdate.h:840 [inline] class_rcu_constructor include/linux/rcupdate.h:1183 [inline] unwind_next_frame+0xd1/0x2090 arch/x86/kernel/unwind_orc.c:495 __unwind_start+0x3cd/0x7e0 arch/x86/kernel/unwind_orc.c:787 unwind_start arch/x86/include/asm/unwind.h:64 [inline] arch_stack_walk+0x73/0xf0 arch/x86/kernel/stacktrace.c:24 stack_trace_save+0x8e/0xc0 kernel/stacktrace.c:122 kasan_save_stack+0x30/0x50 mm/kasan/common.c:57 kasan_save_track+0x14/0x30 mm/kasan/common.c:78 poison_kmalloc_redzone mm/kasan/common.c:398 [inline] __kasan_kmalloc+0xaa/0xb0 mm/kasan/common.c:415 kasan_kmalloc include/linux/kasan.h:263 [inline] __do_kmalloc_node mm/slub.c:5334 [inline] __kmalloc_noprof+0x322/0x820 mm/slub.c:5359 _kmalloc_noprof include/linux/slab.h:992 [inline] _kzalloc_noprof include/linux/slab.h:1309 [inline] tomoyo_encode2+0xfb/0x3c0 security/tomoyo/realpath.c:45 tomoyo_encode+0x29/0x50 security/tomoyo/realpath.c:80 tomoyo_realpath_from_path+0x18c/0x690 security/tomoyo/realpath.c:283 tomoyo_get_realpath security/tomoyo/file.c:151 [inline] tomoyo_path_number_perm+0x23c/0x580 security/tomoyo/file.c:728 security_file_ioctl+0xd3/0x230 security/security.c:2512 __do_sys_ioctl fs/ioctl.c:591 [inline] __se_sys_ioctl fs/ioctl.c:583 [inline] __x64_sys_ioctl+0xb7/0x210 fs/ioctl.c:583 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f459fd6e378 Code: 00 00 48 8d 44 24 08 48 89 54 24 e0 48 89 44 24 c0 48 8d 44 24 d0 48 89 44 24 c8 b8 10 00 00 00 c7 44 24 b8 10 00 00 00 0f 05 <89> c2 3d 00 f0 ff ff 77 07 89 d0 c3 0f 1f 40 00 48 8b 15 49 3a 0d RSP: 002b:00007ffe62aa55d8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 0000565332855a60 RCX: 00007f459fd6e378 RDX: 00007ffe62aa55e0 RSI: 0000000000008921 RDI: 000000000000000f RBP: 00007ffe62aa55e0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00005653328633e0 R13: 0000565332855a60 R14: 00005653328633e0 R15: 00007ffe62aa5830 rcu: rcu_preempt kthread starved for 10502 jiffies! g56737 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=1 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:26264 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5510 [inline] __schedule+0x125c/0x6730 kernel/sched/core.c:7234 __schedule_loop kernel/sched/core.c:7311 [inline] schedule+0xdd/0x2c0 kernel/sched/core.c:7326 schedule_timeout+0x127/0x280 kernel/time/sleep_timeout.c:99 rcu_gp_fqs_loop+0x1a9/0x900 kernel/rcu/tree.c:2123 rcu_gp_kthread+0x179/0x230 kernel/rcu/tree.c:2325 kthread+0x370/0x450 kernel/kthread.c:436 ret_from_fork+0x72b/0xd50 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: 1 UID: 0 PID: 5274 Comm: dhcpcd Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026 RIP: 0010:__sanitizer_cov_trace_pc+0x2a/0x70 kernel/kcov.c:235 Code: f3 0f 1e fa 65 8b 05 e5 df 59 12 48 8b 34 24 65 48 8b 15 c1 df 59 12 a9 00 01 ff 00 74 1b f6 c4 01 74 07 a9 00 00 ff 00 74 05 cc cc cc cc 8b 82 24 17 00 00 85 c0 74 f1 8b 82 f8 16 00 00 83 RSP: 0018:ffffc9000330f5f0 EFLAGS: 00000293 RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffffff81fdc702 RDX: ffff888027274a80 RSI: ffffffff81fdc6dc RDI: ffff888027274a80 RBP: ffff8880b8443680 R08: 0000000000000005 R09: 0000000000000000 R10: 0000000000000001 R11: 0000000000000000 R12: 0000000000000003 R13: ffffed10170886d1 R14: 0000000000000001 R15: ffff8880b853c880 FS: 00007f459fc6e780(0000) GS:ffff888123edc000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fec95fed2f8 CR3: 0000000035010000 CR4: 00000000003526f0 Call Trace: native_pause arch/x86/include/asm/vdso/processor.h:13 [inline] cpu_relax arch/x86/include/asm/vdso/processor.h:18 [inline] csd_lock_wait kernel/smp.c:342 [inline] smp_call_function_many_cond+0x58c/0x1870 kernel/smp.c:912 on_each_cpu_cond_mask+0x40/0x90 kernel/smp.c:1077 __flush_tlb_multi arch/x86/include/asm/paravirt.h:46 [inline] flush_tlb_multi arch/x86/mm/tlb.c:1361 [inline] flush_tlb_mm_range+0x45f/0x16f0 arch/x86/mm/tlb.c:1451 dup_mmap+0x1307/0x21b0 mm/mmap.c:1905 dup_mm kernel/fork.c:1543 [inline] copy_mm kernel/fork.c:1595 [inline] copy_process+0x4588/0x8030 kernel/fork.c:2289 kernel_clone+0x176/0x9d0 kernel/fork.c:2748 __do_sys_clone+0xd9/0x120 kernel/fork.c:2889 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f459fd42636 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:00007ffe62a85450 EFLAGS: 00000246 ORIG_RAX: 0000000000000038 RAX: ffffffffffffffda RBX: 00007ffe62a85458 RCX: 00007f459fd42636 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000001200011 RBP: 00007ffe62aa59a0 R08: 0000000000000000 R09: 0000000000000001 R10: 00007f459fc6ea50 R11: 0000000000000246 R12: 00007ffe62a85590 R13: 0000000000000000 R14: 0000000000000000 R15: 000056531c956ac0