rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: 1-...!: (1 GPs behind) idle=b6c4/1/0x4000000000000002 softirq=106014/106015 fqs=41 rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P18421/1:b..l rcu: (detected by 0, t=10502 jiffies, g=115293, q=250 ncpus=2) Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 UID: 0 PID: 0 Comm: swapper/1 Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026 RIP: 0010:__sanitizer_cov_trace_const_cmp4+0x0/0x20 kernel/kcov.c:313 Code: 0c 24 0f b7 d6 0f b7 f7 bf 03 00 00 00 e9 58 fe ff ff 0f 1f 84 00 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 0f 1e fa 48 8b 0c 24 89 f2 89 fe bf 05 00 00 00 e9 2a fe ff ff RSP: 0018:ffffc90000a08e60 EFLAGS: 00000046 RAX: 0000000000000001 RBX: ffff8880b8528540 RCX: 0000000000000001 RDX: 0000000000000046 RSI: 0000000000000001 RDI: 0000000000000000 RBP: ffff888035a9b300 R08: 0000000000000005 R09: 0000000000000000 R10: 0000000000000001 R11: 0000000000000000 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000001 R15: ffff8880b8528590 FS: 0000000000000000(0000) GS:ffff8881241e0000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f87ef3ea540 CR3: 0000000058fa0000 CR4: 00000000003526f0 Call Trace: enqueue_hrtimer+0x25b/0x2f0 kernel/time/hrtimer.c:1107 __run_hrtimer kernel/time/hrtimer.c:2048 [inline] __hrtimer_run_queues+0x6ed/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:finish_task_switch.isra.0+0x2cd/0x10c0 kernel/sched/core.c:5361 Code: ab 0a 00 00 41 c7 87 20 0e 00 00 00 00 00 00 e9 47 04 00 00 49 8d 7f 48 e8 b0 a4 ca 09 e8 4b ad 3c 00 fb 48 8d bb f8 16 00 00 <48> b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 0f b6 04 02 84 RSP: 0018:ffffc90000197c30 EFLAGS: 00000206 RAX: 000000000642df55 RBX: ffff88801ea92540 RCX: 0000000000000000 RDX: 0000000000000000 RSI: ffffffff8e15d8c3 RDI: ffff88801ea93c38 RBP: ffffc90000197c88 R08: 0000000000000001 R09: 0000000000000000 R10: 0000000000000001 R11: 0000000000000000 R12: ffff888057f50000 R13: 0000000000000000 R14: dffffc0000000000 R15: ffff8880b853b4c0 context_switch kernel/sched/core.c:5513 [inline] __schedule+0x1264/0x6730 kernel/sched/core.c:7234 schedule_idle+0x54/0x80 kernel/sched/core.c:7352 do_idle+0x35e/0x5b0 kernel/sched/idle.c:384 cpu_startup_entry+0x4f/0x60 kernel/sched/idle.c:454 start_secondary+0x21d/0x2d0 arch/x86/kernel/smpboot.c:312 common_startup_64+0x13e/0x158 task:syz-executor state:R running task stack:27312 pid:18421 tgid:18421 ppid:18412 task_flags:0x400140 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5510 [inline] __schedule+0x125c/0x6730 kernel/sched/core.c:7234 preempt_schedule_irq+0x50/0x90 kernel/sched/core.c:7556 irqentry_exit_to_kernel_mode_preempt include/linux/irq-entry-common.h:468 [inline] irqentry_exit_to_kernel_mode include/linux/irq-entry-common.h:539 [inline] irqentry_exit+0x205/0xa00 kernel/entry/common.c:167 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 bb ef 4e 12 83 f8 07 0f 87 da 00 00 00 48 0f a3 05 06 a2 16 0f 0f 82 ac 02 00 00 8b 35 ce d5 16 0f 85 f6 0f 85 c7 00 00 00 <48> 8b 44 24 30 65 48 2b 05 5d ef 4e 12 0f 85 ec 02 00 00 48 83 c4 RSP: 0018:ffffc90005386fd8 EFLAGS: 00000206 RAX: 0000000000000046 RBX: 0000000000000000 RCX: 0000000000000000 RDX: 0000000000000000 RSI: ffffffff8e137c0e RDI: ffffffff8c3e9b80 RBP: ffffffff8e9e60c0 R08: 00000000f0f05a23 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 arch_stack_walk+0x94/0xf0 arch/x86/kernel/stacktrace.c:25 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:5362 [inline] __kmalloc_node_track_caller_noprof+0x331/0x830 mm/slub.c:5497 __kmemdup_nul mm/util.c:64 [inline] kstrdup+0x51/0xe0 mm/util.c:84 kstrdup_const+0x63/0x80 mm/util.c:104 __kernfs_new_node+0x9b/0xa10 fs/kernfs/dir.c:661 kernfs_new_node+0x117/0x150 fs/kernfs/dir.c:751 __kernfs_create_file+0x53/0x350 fs/kernfs/file.c:1050 sysfs_add_file_mode_ns+0x207/0x3c0 fs/sysfs/file.c:316 create_files fs/sysfs/group.c:82 [inline] internal_create_group+0x593/0xfb0 fs/sysfs/group.c:189 internal_create_groups+0x9d/0x150 fs/sysfs/group.c:229 setup_port+0x409/0x16e0 drivers/infiniband/core/sysfs.c:1202 ib_setup_port_attrs+0x201/0x600 drivers/infiniband/core/sysfs.c:1388 add_one_compat_dev+0x5b3/0x820 drivers/infiniband/core/device.c:979 rdma_dev_init_net+0x30a/0x590 drivers/infiniband/core/device.c:1195 ops_init+0x1e2/0x5f0 net/core/net_namespace.c:137 setup_net+0x118/0x3a0 net/core/net_namespace.c:446 copy_net_ns+0x46f/0x7c0 net/core/net_namespace.c:579 create_new_namespaces+0x3ea/0xac0 kernel/nsproxy.c:132 unshare_nsproxy_namespaces+0xf2/0x220 kernel/nsproxy.c:234 ksys_unshare+0x438/0xab0 kernel/fork.c:3268 __do_sys_unshare kernel/fork.c:3342 [inline] __se_sys_unshare kernel/fork.c:3340 [inline] __x64_sys_unshare+0x31/0x40 kernel/fork.c:3340 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: 0033:0x7f98b859e127 RSP: 002b:00007fff474c4f38 EFLAGS: 00000202 ORIG_RAX: 0000000000000110 RAX: ffffffffffffffda RBX: 00007f98b8815f40 RCX: 00007f98b859e127 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000040000000 RBP: 00007f98b88167b8 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000008 R13: 0000000000000003 R14: 00007fff474c5178 R15: 0000000000000000 rcu: rcu_preempt kthread starved for 10420 jiffies! g115293 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:27592 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: 0 UID: 0 PID: 5629 Comm: udevd Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026 RIP: 0010:csd_lock_wait kernel/smp.c:342 [inline] RIP: 0010:smp_call_function_many_cond+0x593/0x16c0 kernel/smp.c:892 Code: 8b 54 24 08 49 89 d5 49 89 d4 49 c1 ed 03 41 83 e4 07 49 01 c5 41 83 c4 03 e8 b9 95 0c 00 f3 90 41 0f b6 45 00 41 38 c4 7c 08 <84> c0 0f 85 2c 0f 00 00 8b 45 08 31 ff 83 e0 01 41 89 c6 89 c6 e8 RSP: 0018:ffffc9000306f5f0 EFLAGS: 00000206 RAX: 0000000000000000 RBX: 0000000000000001 RCX: ffffffff81fcea8d RDX: ffff88807cacca80 RSI: ffffffff81fcea67 RDI: ffff88807cacca80 RBP: ffff8880b8541240 R08: 0000000000000005 R09: 0000000000000000 R10: 0000000000000001 R11: 0000000000000000 R12: 0000000000000003 R13: ffffed10170a8249 R14: 0000000000000001 R15: ffff8880b843c880 FS: 00007f28729c6880(0000) GS:ffff8881240e0000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00005559f0ca5658 CR3: 000000005a515000 CR4: 00000000003526f0 Call Trace: on_each_cpu_cond_mask+0x40/0x90 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+0x45f/0x16f0 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_tlbonly include/asm-generic/tlb.h:499 [inline] tlb_flush_mmu mm/mmu_gather.c:423 [inline] tlb_finish_mmu+0x3fe/0x810 mm/mmu_gather.c:549 unmap_region+0x2d9/0x3b0 mm/vma.c:491 vms_clear_ptes mm/vma.c:1303 [inline] vms_complete_munmap_vmas+0xa4b/0xdd0 mm/vma.c:1345 do_vmi_align_munmap+0x44f/0x5f0 mm/vma.c:1604 do_vmi_munmap+0x1f8/0x3e0 mm/vma.c:1652 __vm_munmap+0x196/0x390 mm/vma.c:3288 __do_sys_munmap mm/mmap.c:1079 [inline] __se_sys_munmap mm/mmap.c:1076 [inline] __x64_sys_munmap+0x59/0x80 mm/mmap.c:1076 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: 0033:0x7f287231e097 Code: 73 01 c3 48 8b 0d 61 2d 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 0b 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 31 2d 0d 00 f7 d8 64 89 01 48 RSP: 002b:00007ffe1f549838 EFLAGS: 00000206 ORIG_RAX: 000000000000000b RAX: ffffffffffffffda RBX: 00005559f0a4ef90 RCX: 00007f287231e097 RDX: 0000000000000000 RSI: 00000000009480e8 RDI: 00007f2871600000 RBP: 00005559f0a4c2c0 R08: 00005559f0c8c660 R09: 0000000000000006 R10: 0000000000000000 R11: 0000000000000206 R12: 00005559ebb4a588 R13: 00007ffe1f5498c0 R14: 0000000000000000 R15: 0000000000000000