rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: 1-...!: (0 ticks this GP) idle=bb5c/1/0x4000000000000000 softirq=88791/88791 fqs=1 rcu: (detected by 0, t=10502 jiffies, g=83645, q=121 ncpus=2) Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 UID: 0 PID: 17085 Comm: syz.4.2796 Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 RIP: 0010:__lock_release kernel/locking/lockdep.c:5514 [inline] RIP: 0010:lock_release+0xa9/0x3b0 kernel/locking/lockdep.c:5889 Code: 00 0f 85 f7 01 00 00 49 81 3e c0 33 66 93 0f 84 ea 01 00 00 9c 5b fa 48 c7 c7 d9 b9 9b 8d e8 0e 2e c0 09 65 ff 05 27 26 04 11 44 24 24 01 00 00 00 83 3d 78 7a 04 0e 00 0f 84 90 01 00 00 41 RSP: 0018:ffffc90000a08cc0 EFLAGS: 00000002 RAX: 0000000000000001 RBX: 0000000000000087 RCX: 0000000000010002 RDX: 0000000000010000 RSI: ffffffff8d9bb9d9 RDI: ffffffff8be09760 RBP: ffffc90000a08e90 R08: ffffffff8fa2d9f7 R09: 1ffffffff1f45b3e R10: dffffc0000000000 R11: fffffbfff1f45b3f R12: ffff88802fd64300 R13: ffffffff81ae9168 R14: ffff8880b8728298 R15: ffff8880284f5ac0 FS: 00007f7a80bf66c0(0000) GS:ffff888125cf9000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f7a80bf5f98 CR3: 0000000021f9e000 CR4: 00000000003526f0 Call Trace: __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:176 [inline] _raw_spin_unlock_irqrestore+0x1b/0x80 kernel/locking/spinlock.c:194 __run_hrtimer kernel/time/hrtimer.c:1781 [inline] __hrtimer_run_queues+0x408/0xc30 kernel/time/hrtimer.c:1849 hrtimer_interrupt+0x45b/0xaa0 kernel/time/hrtimer.c:1911 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:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:179 [inline] RIP: 0010:_raw_spin_unlock_irqrestore+0x47/0x80 kernel/locking/spinlock.c:194 Code: f7 e8 8d cb 3d f6 f7 c3 00 02 00 00 74 05 e8 30 a9 67 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 d6 2f f6 65 8b 05 1d 39 41 07 85 c0 74 18 5b 41 5e e9 01 47 RSP: 0018:ffffc900102b7a50 EFLAGS: 00000206 RAX: 0000000000000006 RBX: 0000000000000202 RCX: 0000000080000001 RDX: 0000000000000000 RSI: ffffffff8d9a7414 RDI: 0000000000000001 RBP: ffff888056a330d8 R08: ffffffff8fa2d9f7 R09: 1ffffffff1f45b3e R10: dffffc0000000000 R11: fffffbfff1f45b3f R12: dffffc0000000000 R13: 71e66100b78b382a R14: ffff888056a33088 R15: ffff888056a330f8 spin_unlock_irqrestore include/linux/spinlock.h:410 [inline] timerfd_clock_was_set+0x1ce/0x2c0 fs/timerfd.c:111 clock_was_set+0x73b/0x7c0 kernel/time/hrtimer.c:983 do_adjtimex+0x228/0x310 kernel/time/timekeeping.c:2767 do_clock_adjtime kernel/time/posix-timers.c:1154 [inline] __do_sys_clock_adjtime kernel/time/posix-timers.c:1166 [inline] __se_sys_clock_adjtime kernel/time/posix-timers.c:1157 [inline] __x64_sys_clock_adjtime+0x211/0x2c0 kernel/time/posix-timers.c:1157 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xec/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f7a8298f749 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f7a80bf6038 EFLAGS: 00000246 ORIG_RAX: 0000000000000131 RAX: ffffffffffffffda RBX: 00007f7a82be6090 RCX: 00007f7a8298f749 RDX: 0000000000000000 RSI: 0000200000000280 RDI: 0000000000000000 RBP: 00007f7a82a13f91 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f7a82be6128 R14: 00007f7a82be6090 R15: 00007ffcee0ffce8 rcu: rcu_preempt kthread starved for 10500 jiffies! g83645 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:27680 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5290 [inline] __schedule+0x14db/0x5030 kernel/sched/core.c:6902 __schedule_loop kernel/sched/core.c:6984 [inline] schedule+0x165/0x360 kernel/sched/core.c:6999 schedule_timeout+0x12b/0x270 kernel/time/sleep_timeout.c:99 rcu_gp_fqs_loop+0x301/0x11b0 kernel/rcu/tree.c:2095 rcu_gp_kthread+0x9b/0x2d0 kernel/rcu/tree.c:2297 kthread+0x389/0x480 kernel/kthread.c:467 ret_from_fork+0x510/0xa50 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: 17083 Comm: syz.5.2800 Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP 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+0xcc5/0x1260 kernel/smp.c:877 Code: 45 8b 2c 24 44 89 ee 83 e6 01 31 ff e8 b4 9a 0b 00 41 83 e5 01 49 bd 00 00 00 00 00 fc ff df 75 07 e8 5f 96 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 43 96 RSP: 0018:ffffc900100972e0 EFLAGS: 00000246 RAX: ffffffff81b5835d RBX: 1ffff110170e8179 RCX: 0000000000080000 RDX: ffffc90012c09000 RSI: 000000000007ffff RDI: 0000000000080000 RBP: ffffc90010097420 R08: ffffffff8fa2d9f7 R09: 1ffffffff1f45b3e R10: dffffc0000000000 R11: fffffbfff1f45b3f R12: ffff8880b8740bc8 R13: dffffc0000000000 R14: ffff8880b863bd80 R15: 0000000000000001 FS: 00007fc1b81b76c0(0000) GS:ffff888125bf9000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000000110c36ad61 CR3: 0000000075c66000 CR4: 00000000003526f0 Call Trace: on_each_cpu_cond_mask+0x3f/0x80 kernel/smp.c:1043 __flush_tlb_multi arch/x86/include/asm/paravirt.h:57 [inline] flush_tlb_multi arch/x86/mm/tlb.c:1382 [inline] flush_tlb_mm_range+0x5db/0x1100 arch/x86/mm/tlb.c:1472 tlb_flush arch/x86/include/asm/tlb.h:23 [inline] tlb_flush_mmu_tlbonly include/asm-generic/tlb.h:505 [inline] tlb_flush_mmu+0x1a7/0x680 mm/mmu_gather.c:403 tlb_finish_mmu+0xf9/0x230 mm/mmu_gather.c:529 vms_clear_ptes+0x42b/0x530 mm/vma.c:1278 vms_clean_up_area mm/vma.c:1290 [inline] __mmap_setup mm/vma.c:2442 [inline] __mmap_region mm/vma.c:2734 [inline] mmap_region+0x96f/0x1d40 mm/vma.c:2830 do_mmap+0xc45/0x10d0 mm/mmap.c:558 do_shmat+0x96a/0xca0 ipc/shm.c:1662 __do_sys_shmat ipc/shm.c:1698 [inline] __se_sys_shmat ipc/shm.c:1693 [inline] __x64_sys_shmat+0x9c/0xf0 ipc/shm.c:1693 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xec/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fc1b738f749 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fc1b81b7038 EFLAGS: 00000246 ORIG_RAX: 000000000000001e RAX: ffffffffffffffda RBX: 00007fc1b75e5fa0 RCX: 00007fc1b738f749 RDX: bbdccba4532b703b RSI: 0000200000000000 RDI: 0000000000000000 RBP: 00007fc1b7413f91 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fc1b75e6038 R14: 00007fc1b75e5fa0 R15: 00007fffd0616658