rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: 1-...!: (2 GPs behind) idle=e1fc/1/0x4000000000000000 softirq=21818/21823 fqs=0 rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P6372/1:b..l rcu: (detected by 0, t=10504 jiffies, g=16565, q=666 ncpus=2) Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 UID: 0 PID: 5202 Comm: udevd Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 RIP: 0010:mark_usage kernel/locking/lockdep.c:4641 [inline] RIP: 0010:__lock_acquire+0x66f/0x2cf0 kernel/locking/lockdep.c:5191 Code: ee ba 05 00 00 00 eb 38 85 c9 74 19 31 ed 48 8b 7c 24 08 4c 89 ee 31 d2 e8 ee 47 00 00 85 c0 0f 84 c3 0d 00 00 48 8b 44 24 08 <83> b8 14 0b 00 00 00 74 1a 48 8b 7c 24 08 4c 89 ee ba 04 00 00 00 RSP: 0018:ffffc90000a08ab8 EFLAGS: 00000002 RAX: ffff88807eb7db80 RBX: 0000000000000001 RCX: ffffffff931ffd88 RDX: 0000000000000000 RSI: ffff88807eb7e6d8 RDI: ffff88807eb7db80 RBP: 0000000000000000 R08: ffffffff81aec4a2 R09: ffff8880b8928118 R10: dffffc0000000000 R11: fffffbfff1f00b4f R12: ffffffffffffff02 R13: ffff88807eb7e6d8 R14: ffff88807eb7db80 R15: 0000000000000000 FS: 00007f908e1cb880(0000) GS:ffff8881261b1000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000563f173c0950 CR3: 0000000031f42000 CR4: 00000000003526f0 Call Trace: lock_acquire+0x117/0x340 kernel/locking/lockdep.c:5868 __raw_spin_lock_irq include/linux/spinlock_api_smp.h:119 [inline] _raw_spin_lock_irq+0xa2/0xf0 kernel/locking/spinlock.c:170 __run_hrtimer kernel/time/hrtimer.c:1781 [inline] __hrtimer_run_queues+0x5e2/0xc30 kernel/time/hrtimer.c:1841 hrtimer_interrupt+0x45b/0xaa0 kernel/time/hrtimer.c:1903 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1045 [inline] __sysvec_apic_timer_interrupt+0x102/0x3e0 arch/x86/kernel/apic/apic.c:1062 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1056 [inline] sysvec_apic_timer_interrupt+0xa1/0xc0 arch/x86/kernel/apic/apic.c:1056 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697 RIP: 0010:__slab_alloc+0x6d/0x100 mm/slub.c:4777 Code: 8d 41 f7 c7 00 0c 00 00 74 47 4c 89 e7 44 89 fe 89 ea 4c 89 f1 4d 89 e8 44 8b 4c 24 04 e8 ab 00 00 00 48 89 c3 bf 01 00 00 00 6e 37 74 ff 65 8b 05 e7 64 5a 10 85 c0 74 49 48 89 d8 48 83 c4 RSP: 0018:ffffc90003347870 EFLAGS: 00000282 RAX: ffff888059d20000 RBX: ffff888059d20000 RCX: 72829f405610f000 RDX: 0000000000000007 RSI: ffffffff8d76bd39 RDI: 0000000000000001 RBP: 00000000ffffffff R08: ffffffff8f805a77 R09: 1ffffffff1f00b4e R10: dffffc0000000000 R11: fffffbfff1f00b4f R12: ffff88801a027140 R13: ffff8880b893f030 R14: ffffffff84416373 R15: 0000000000000c40 __slab_alloc_node mm/slub.c:4850 [inline] slab_alloc_node mm/slub.c:5246 [inline] __do_kmalloc_node mm/slub.c:5651 [inline] __kmalloc_noprof+0x471/0x800 mm/slub.c:5664 kmalloc_noprof include/linux/slab.h:961 [inline] tomoyo_realpath_from_path+0xe3/0x5d0 security/tomoyo/realpath.c:251 tomoyo_get_realpath security/tomoyo/file.c:151 [inline] tomoyo_path_perm+0x213/0x4b0 security/tomoyo/file.c:822 security_inode_getattr+0x12f/0x330 security/security.c:1869 vfs_getattr fs/stat.c:259 [inline] vfs_statx_path fs/stat.c:299 [inline] vfs_statx+0x18e/0x550 fs/stat.c:356 vfs_fstatat+0x118/0x170 fs/stat.c:375 __do_sys_newfstatat fs/stat.c:542 [inline] __se_sys_newfstatat fs/stat.c:536 [inline] __x64_sys_newfstatat+0x116/0x190 fs/stat.c:536 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f908db11b0a Code: 48 8b 15 f1 f2 0d 00 f7 d8 64 89 02 b8 ff ff ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 41 89 ca b8 06 01 00 00 0f 05 <3d> 00 f0 ff ff 77 07 31 c0 c3 0f 1f 40 00 48 8b 15 b9 f2 0d 00 f7 RSP: 002b:00007ffd4d90c2e8 EFLAGS: 00000246 ORIG_RAX: 0000000000000106 RAX: ffffffffffffffda RBX: 0000556982d70418 RCX: 00007f908db11b0a RDX: 00007ffd4d90c2f0 RSI: 0000556982d5eef3 RDI: 00000000ffffff9c RBP: 00005569c1840148 R08: 000645f19a7a6182 R09: 3fffffffffffffff R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001 R13: 00007ffd4d90c2f0 R14: 0000000000000000 R15: 000645f19a7a6182 task:syz-executor state:R running task stack:21240 pid:6372 tgid:6372 ppid:6364 task_flags:0x400140 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5256 [inline] __schedule+0x14bc/0x5000 kernel/sched/core.c:6863 preempt_schedule_notrace+0xd1/0x110 kernel/sched/core.c:7140 preempt_schedule_notrace_thunk+0x16/0x30 arch/x86/entry/thunk.S:13 rcu_is_watching+0x7f/0xb0 kernel/rcu/tree.c:752 trace_notifier_run include/trace/events/notifier.h:59 [inline] notifier_call_chain+0x158/0x3a0 kernel/notifier.c:84 atomic_notifier_call_chain+0xda/0x180 kernel/notifier.c:223 ipv6_add_addr+0xda9/0x1090 net/ipv6/addrconf.c:1186 inet6_addr_add+0x3c3/0xce0 net/ipv6/addrconf.c:3050 inet6_rtm_newaddr+0x93d/0xd20 net/ipv6/addrconf.c:5059 rtnetlink_rcv_msg+0x7cf/0xb70 net/core/rtnetlink.c:6958 netlink_rcv_skb+0x208/0x470 net/netlink/af_netlink.c:2550 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline] netlink_unicast+0x82f/0x9e0 net/netlink/af_netlink.c:1344 netlink_sendmsg+0x805/0xb30 net/netlink/af_netlink.c:1894 sock_sendmsg_nosec net/socket.c:718 [inline] __sock_sendmsg+0x21c/0x270 net/socket.c:733 __sys_sendto+0x3bd/0x520 net/socket.c:2222 __do_sys_sendto net/socket.c:2229 [inline] __se_sys_sendto net/socket.c:2225 [inline] __x64_sys_sendto+0xde/0x100 net/socket.c:2225 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f4e46390a3c RSP: 002b:00007fffc453e150 EFLAGS: 00000293 ORIG_RAX: 000000000000002c RAX: ffffffffffffffda RBX: 00007f4e47104620 RCX: 00007f4e46390a3c RDX: 0000000000000040 RSI: 00007f4e47104670 RDI: 0000000000000003 RBP: 0000000000000000 R08: 00007fffc453e1a4 R09: 000000000000000c R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000003 R13: 0000000000000000 R14: 00007f4e47104670 R15: 0000000000000000 rcu: rcu_preempt kthread starved for 10504 jiffies! g16565 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:27200 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5256 [inline] __schedule+0x14bc/0x5000 kernel/sched/core.c:6863 __schedule_loop kernel/sched/core.c:6945 [inline] schedule+0x165/0x360 kernel/sched/core.c:6960 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+0x599/0xb30 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246 rcu: Stack dump where RCU GP kthread last ran: CPU: 0 UID: 0 PID: 6357 Comm: syz-executor Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 RIP: 0010:csd_lock_wait kernel/smp.c:342 [inline] RIP: 0010:smp_call_function_many_cond+0xccf/0x12b0 kernel/smp.c:877 Code: 45 8b 2c 24 44 89 ee 83 e6 01 31 ff e8 4a 94 0b 00 41 83 e5 01 49 bd 00 00 00 00 00 fc ff df 75 07 e8 f5 8f 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 d9 8f RSP: 0018:ffffc9000399f560 EFLAGS: 00000293 RAX: ffffffff81b5ba87 RBX: 1ffff11017128101 RCX: ffff88802b839e80 RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000 RBP: ffffc9000399f6e0 R08: ffffffff8f805a77 R09: 1ffffffff1f00b4e R10: dffffc0000000000 R11: fffffbfff1f00b4f R12: ffff8880b8940808 R13: dffffc0000000000 R14: ffff8880b883b9c0 R15: 0000000000000001 FS: 0000555560f39500(0000) GS:ffff8881260b1000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fe54c3056c0 CR3: 0000000077dbe000 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:1382 [inline] flush_tlb_mm_range+0x6b1/0x1280 arch/x86/mm/tlb.c:1472 dup_mmap+0x1594/0x1b10 mm/mmap.c:1873 dup_mm kernel/fork.c:1486 [inline] copy_mm+0x13c/0x4b0 kernel/fork.c:1538 copy_process+0x165d/0x3950 kernel/fork.c:2178 kernel_clone+0x21e/0x820 kernel/fork.c:2608 __do_sys_clone kernel/fork.c:2749 [inline] __se_sys_clone kernel/fork.c:2733 [inline] __x64_sys_clone+0x18b/0x1e0 kernel/fork.c:2733 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fe54b585413 Code: 1f 84 00 00 00 00 00 64 48 8b 04 25 10 00 00 00 45 31 c0 31 d2 31 f6 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 35 89 c2 85 c0 75 2c 64 48 8b 04 25 10 00 00 RSP: 002b:00007ffe43fc1cf8 EFLAGS: 00000246 ORIG_RAX: 0000000000000038 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fe54b585413 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000001200011 RBP: 0000000000000001 R08: 0000000000000000 R09: 0000000000000001 R10: 0000555560f397d0 R11: 0000000000000246 R12: 0000000000000000 R13: 00000000000927c0 R14: 00000000000206d9 R15: 00007ffe43fc1e90