rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: 0-...!: (1 GPs behind) idle=7a14/1/0x4000000000000000 softirq=16083/16086 fqs=0 rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P5965/1:b..l rcu: (detected by 1, t=10505 jiffies, g=16153, q=230 ncpus=2) Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 UID: 0 PID: 6028 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026 RIP: 0010:rcu_is_watching_curr_cpu include/linux/context_tracking.h:128 [inline] RIP: 0010:rcu_is_watching+0x10/0xb0 kernel/rcu/tree.c:752 Code: 66 2e 0f 1f 84 00 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 41 57 41 56 53 65 ff 05 30 dc 95 11 3b 0c 0e 0a 89 c3 83 f8 08 73 65 49 bf 00 00 00 00 00 fc ff df RSP: 0018:ffffc90000007c68 EFLAGS: 00000007 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff9a7c1040 RBP: ffffffff84bc2fc3 R08: 0000000000000001 R09: 0000000000000000 R10: dffffc0000000000 R11: fffff52000000fac R12: 0000000000000000 R13: ffffffff9a7c1040 R14: 0000000000000000 R15: 0000000000000001 FS: 00007f57b8bb56c0(0000) GS:ffff888125213000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00002000000012c0 CR3: 000000003318c000 CR4: 00000000003526f0 Call Trace: trace_lock_acquire include/trace/events/lock.h:24 [inline] lock_acquire+0x5f/0x350 kernel/locking/lockdep.c:5831 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:132 [inline] _raw_spin_lock_irqsave+0x40/0x60 kernel/locking/spinlock.c:166 debug_object_activate+0x83/0x580 lib/debugobjects.c:835 debug_hrtimer_activate kernel/time/hrtimer.c:485 [inline] debug_activate kernel/time/hrtimer.c:528 [inline] enqueue_hrtimer+0xa9/0x2c0 kernel/time/hrtimer.c:1109 __run_hrtimer kernel/time/hrtimer.c:1946 [inline] __hrtimer_run_queues+0x4d2/0xa20 kernel/time/hrtimer.c:1994 hrtimer_interrupt+0x44b/0x950 kernel/time/hrtimer.c:2113 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1050 [inline] __sysvec_apic_timer_interrupt+0x102/0x430 arch/x86/kernel/apic/apic.c:1067 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1061 [inline] sysvec_apic_timer_interrupt+0xa1/0xc0 arch/x86/kernel/apic/apic.c:1061 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697 RIP: 0010:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:179 [inline] RIP: 0010:_raw_spin_unlock_irqrestore+0x47/0x80 kernel/locking/spinlock.c:198 Code: f7 e8 8d e4 e6 f5 f7 c3 00 02 00 00 74 05 e8 90 6f 12 f6 9c 58 a9 00 02 00 00 75 27 f7 c3 00 02 00 00 74 01 fb bf 01 00 00 00 d4 66 d8 f5 65 8b 05 1d 43 85 07 85 c0 74 18 5b 41 5e e9 41 48 RSP: 0018:ffffc90003316ee8 EFLAGS: 00000206 RAX: 0000000000000002 RBX: 0000000000000282 RCX: 0000000080000202 RDX: 0000000000000002 RSI: ffffffff8dfd8f45 RDI: 0000000000000001 RBP: ffffc900033171d0 R08: ffffffff903386f7 R09: 1ffffffff20670de R10: dffffc0000000000 R11: fffffbfff20670df R12: ffff8880781e0290 R13: dffffc0000000000 R14: ffff8880781e02a8 R15: ffff8880781e02f8 spin_unlock_irqrestore include/linux/spinlock.h:408 [inline] taprio_change+0x30fe/0x3e50 net/sched/sch_taprio.c:1986 taprio_init+0x96f/0xbe0 net/sched/sch_taprio.c:2125 qdisc_create+0x7c4/0xf20 net/sched/sch_api.c:1319 __tc_modify_qdisc net/sched/sch_api.c:1753 [inline] tc_modify_qdisc+0x16f0/0x2290 net/sched/sch_api.c:1817 rtnetlink_rcv_msg+0x77e/0xbe0 net/core/rtnetlink.c:7004 netlink_rcv_skb+0x232/0x4b0 net/netlink/af_netlink.c:2550 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline] netlink_unicast+0x75c/0x8e0 net/netlink/af_netlink.c:1344 netlink_sendmsg+0x813/0xb40 net/netlink/af_netlink.c:1894 sock_sendmsg_nosec net/socket.c:787 [inline] __sock_sendmsg net/socket.c:802 [inline] ____sys_sendmsg+0x972/0x9f0 net/socket.c:2698 ___sys_sendmsg+0x2a5/0x360 net/socket.c:2752 __sys_sendmsg net/socket.c:2784 [inline] __do_sys_sendmsg net/socket.c:2789 [inline] __se_sys_sendmsg net/socket.c:2787 [inline] __x64_sys_sendmsg+0x1bd/0x2a0 net/socket.c:2787 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f57b7d9cdd9 Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f57b8bb5028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 00007f57b8015fa0 RCX: 00007f57b7d9cdd9 RDX: 0000000000000010 RSI: 00002000000012c0 RDI: 0000000000000005 RBP: 00007f57b7e32d69 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f57b8016038 R14: 00007f57b8015fa0 R15: 00007ffdff7f00a8 task:udevd state:R running task stack:26016 pid:5965 tgid:5965 ppid:5210 task_flags:0x400140 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5387 [inline] __schedule+0x17b4/0x5680 kernel/sched/core.c:7188 preempt_schedule_irq+0x4d/0xa0 kernel/sched/core.c:7512 irqentry_exit_to_kernel_mode include/linux/irq-entry-common.h:547 [inline] irqentry_exit+0x14f/0x730 kernel/entry/common.c:164 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697 RIP: 0010:on_stack arch/x86/include/asm/stacktrace.h:55 [inline] RIP: 0010:stack_access_ok arch/x86/kernel/unwind_orc.c:409 [inline] RIP: 0010:deref_stack_reg+0x33/0x230 arch/x86/kernel/unwind_orc.c:419 Code: 53 48 83 ec 20 48 89 54 24 18 49 89 f0 49 89 ff 48 be 00 00 00 00 00 fc ff df 48 8d 5f 08 49 89 dc 49 c1 ec 03 41 80 3c 34 00 <4c> 89 04 24 74 16 48 89 df e8 3f d2 b9 00 4c 8b 04 24 48 be 00 00 RSP: 0018:ffffc900043372c0 EFLAGS: 00000246 RAX: fffffffffffffff0 RBX: ffffc900043373f0 RCX: 0000000000000000 RDX: ffffc90004337428 RSI: dffffc0000000000 RDI: ffffc900043373e8 RBP: dffffc0000000000 R08: ffffc90004337950 R09: 0000000000000000 R10: ffffc90004337438 R11: fffff52000866e89 R12: 1ffff92000866e7e R13: 1ffff92000866e7f R14: ffffc900043373e8 R15: ffffc900043373e8 unwind_next_frame+0x19d5/0x2550 arch/x86/kernel/unwind_orc.c:-1 arch_stack_walk+0x11b/0x150 arch/x86/kernel/stacktrace.c:25 stack_trace_save+0xa9/0x100 kernel/stacktrace.c:122 kasan_save_stack mm/kasan/common.c:57 [inline] kasan_save_track+0x3e/0x80 mm/kasan/common.c:78 kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:584 poison_slab_object mm/kasan/common.c:253 [inline] __kasan_slab_free+0x5c/0x80 mm/kasan/common.c:285 kasan_slab_free include/linux/kasan.h:235 [inline] slab_free_hook mm/slub.c:2689 [inline] slab_free mm/slub.c:6246 [inline] kmem_cache_free+0x182/0x650 mm/slub.c:6373 file_free+0x24/0x1d0 fs/file_table.c:97 __fput_deferred+0x2a3/0x380 fs/file_table.c:565 fput_close+0x11f/0x240 fs/file_table.c:627 path_openat+0x311d/0x3860 fs/namei.c:4867 do_file_open+0x23e/0x4a0 fs/namei.c:4887 do_sys_openat2+0x113/0x200 fs/open.c:1364 do_sys_open fs/open.c:1370 [inline] __do_sys_openat fs/open.c:1386 [inline] __se_sys_openat fs/open.c:1381 [inline] __x64_sys_openat+0x138/0x170 fs/open.c:1381 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7ff6e60a7407 RSP: 002b:00007ffe1a606a20 EFLAGS: 00000202 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 00007ff6e68a2880 RCX: 00007ff6e60a7407 RDX: 0000000000080000 RSI: 00007ff6e69b0f48 RDI: 000000000000000b RBP: 000055e6d5a5e1b0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000080000 R13: 00007ff6e69b0f48 R14: 0000000000000000 R15: 0000000000000009 rcu: rcu_preempt kthread starved for 10505 jiffies! g16153 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:27968 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5387 [inline] __schedule+0x17b4/0x5680 kernel/sched/core.c:7188 __schedule_loop kernel/sched/core.c:7267 [inline] schedule+0x164/0x360 kernel/sched/core.c:7282 schedule_timeout+0x158/0x2c0 kernel/time/sleep_timeout.c:99 rcu_gp_fqs_loop+0x312/0x11d0 kernel/rcu/tree.c:2095 rcu_gp_kthread+0x9e/0x2b0 kernel/rcu/tree.c:2297 kthread+0x388/0x470 kernel/kthread.c:436 ret_from_fork+0x514/0xb70 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: 6026 Comm: sed Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026 RIP: 0010:csd_lock_wait kernel/smp.c:342 [inline] RIP: 0010:smp_call_function_many_cond+0xfd4/0x13d0 kernel/smp.c:892 Code: 89 ee 83 e6 01 31 ff e8 fa fc 0b 00 41 83 e5 01 49 bd 00 00 00 00 00 fc ff df 75 07 e8 a5 f8 0b 00 eb 37 f3 90 43 0f b6 04 2c <84> c0 75 10 41 f7 06 01 00 00 00 74 1e e8 8a f8 0b 00 eb e5 44 89 RSP: 0018:ffffc90004377680 EFLAGS: 00000293 RAX: 0000000000000000 RBX: ffff8880b873c148 RCX: ffff8880337c0000 RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000 RBP: ffffc900043777c0 R08: ffffffff903386f7 R09: 1ffffffff20670de R10: dffffc0000000000 R11: fffffbfff20670df R12: 1ffff110170c8589 R13: dffffc0000000000 R14: ffff8880b8642c48 R15: 0000000000000000 FS: 0000000000000000(0000) GS:ffff888125313000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f1a982a9e9c CR3: 000000000e74a000 CR4: 00000000003526f0 Call Trace: on_each_cpu_cond_mask+0x3f/0x80 kernel/smp.c:1057 __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+0x5c3/0x10b0 arch/x86/mm/tlb.c:1451 tlb_flush arch/x86/include/asm/tlb.h:23 [inline] tlb_flush_mmu_tlbonly include/asm-generic/tlb.h:509 [inline] tlb_flush_mmu+0x1af/0xa30 mm/mmu_gather.c:423 tlb_finish_mmu+0xf9/0x230 mm/mmu_gather.c:549 free_ldt_pgtables+0x19d/0x350 arch/x86/kernel/ldt.c:411 arch_exit_mmap arch/x86/include/asm/mmu_context.h:229 [inline] exit_mmap+0x1af/0x9e0 mm/mmap.c:1285 __mmput+0x118/0x430 kernel/fork.c:1178 exit_mm+0x18e/0x250 kernel/exit.c:581 do_exit+0x6a2/0x22c0 kernel/exit.c:963 do_group_exit+0x21b/0x2d0 kernel/exit.c:1117 __do_sys_exit_group kernel/exit.c:1128 [inline] __se_sys_exit_group kernel/exit.c:1126 [inline] __x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1126 x64_sys_call+0x221a/0x2240 arch/x86/include/generated/asm/syscalls_64.h:232 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f1a984086c5 Code: Unable to access opcode bytes at 0x7f1a9840869b. RSP: 002b:00007fffc18bbd08 EFLAGS: 00000206 ORIG_RAX: 00000000000000e7 RAX: ffffffffffffffda RBX: 00007f1a98509fe8 RCX: 00007f1a984086c5 RDX: 00000000000000e7 RSI: ffffffffffffff88 RDI: 0000000000000000 RBP: 0000000000000001 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000000 R13: 0000000000000000 R14: 00007f1a98508680 R15: 00007f1a9850a000