INFO: rcu detected stall in raw_ioctl

Status: upstream: reported on 2026/09/27 11:16
Reported-by: syzbot+665b28332e5bf3718817@syzkaller.appspotmail.com
First crash: 3d23h, last: 3d23h
▶ ▼ Similar bugs (5)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream BUG: soft lockup in raw_ioctl serial kvm net 1 3 1309d 1412d 0/29 auto-obsoleted due to no activity on 2023/05/31 06:54
upstream INFO: rcu detected stall in raw_ioctl (2) mm usb 1 26 405d 812d 0/29 auto-obsoleted due to no activity on 2025/11/19 12:30
upstream INFO: rcu detected stall in raw_ioctl usb 1 syz, C 49 820d 1066d 26/29 fixed on 2024/07/09 19:14
upstream INFO: rcu detected stall in raw_ioctl (3) usb 1 3 229d 297d 0/29 auto-obsoleted due to no activity on 2026/05/15 09:41
android-5-15 BUG: soft lockup in raw_ioctl 1 20 801d 899d 0/2 auto-obsoleted due to no activity on 2024/10/01 04:08

Sample crash report:
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	1-...!: (1 GPs behind) idle=81fc/1/0x4000000000000000 softirq=39538/39538 fqs=54
	(detected by 0, t=10505 jiffies, g=61205, q=754 ncpus=2)
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 9408 Comm: syz.3.1636 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:variable_test_bit arch/x86/include/asm/bitops.h:228 [inline]
RIP: 0010:arch_test_bit arch/x86/include/asm/bitops.h:240 [inline]
RIP: 0010:_test_bit include/asm-generic/bitops/instrumented-non-atomic.h:142 [inline]
RIP: 0010:hlock_class kernel/locking/lockdep.c:228 [inline]
RIP: 0010:check_wait_context kernel/locking/lockdep.c:4729 [inline]
RIP: 0010:__lock_acquire+0x5f5/0x7c40 kernel/locking/lockdep.c:5013
Code: 0f 85 36 61 00 00 41 8b 07 89 c3 81 e3 ff 1f 00 00 c1 e8 03 25 f8 03 00 00 48 8d b8 40 f2 b0 90 be 08 00 00 00 e8 5b 73 6f 00 <48> 0f a3 1d 63 ec 4c 0f 73 1a 48 8d 04 5b c1 e0 06 48 8d 98 00 71
RSP: 0018:ffffc900001e0940 EFLAGS: 00000056
RAX: 0000000000000001 RBX: 0000000000000060 RCX: ffffffff816405d5
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff90b0f248
RBP: ffffc900001e0b70 R08: ffffffff90b0f24f R09: 1ffffffff2161e49
R10: dffffc0000000000 R11: fffffbfff2161e4a R12: ffff88802fe3e4d8
R13: ffff88802fe3da00 R14: 0000000000000002 R15: ffff88802fe3e528
FS:  00007f62c4c486c0(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f62c3d872c0 CR3: 0000000029a8e000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <IRQ>
 lock_acquire+0x1bb/0x4a0 kernel/locking/lockdep.c:5678
 __raw_spin_lock_irq include/linux/spinlock_api_smp.h:119 [inline]
 _raw_spin_lock_irq+0xab/0xf0 kernel/locking/spinlock.c:170
 __run_hrtimer kernel/time/hrtimer.c:1755 [inline]
 __hrtimer_run_queues+0x5e9/0xc90 kernel/time/hrtimer.c:1815
 hrtimer_interrupt+0x399/0x980 kernel/time/hrtimer.c:1877
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1107 [inline]
 __sysvec_apic_timer_interrupt+0x153/0x5a0 arch/x86/kernel/apic/apic.c:1124
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1118 [inline]
 sysvec_apic_timer_interrupt+0x9b/0xc0 arch/x86/kernel/apic/apic.c:1118
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691
RIP: 0010:lock_acquire+0x225/0x4a0 kernel/locking/lockdep.c:5682
Code: f7 84 24 80 00 00 00 00 02 00 00 43 c6 44 3d 04 f8 0f 85 f0 00 00 00 41 f7 c6 00 02 00 00 74 01 fb 48 c7 44 24 60 0e 36 e0 45 <4b> c7 44 3d 00 00 00 00 00 43 c7 44 3d 08 00 00 00 00 65 48 8b 04
RSP: 0018:ffffc9000555f4a0 EFLAGS: 00000206
RAX: 0000000000000001 RBX: 0000000000000000 RCX: 51fbf0e973f28e00
RDX: 0000000000000000 RSI: ffffffff8a8c2a20 RDI: ffffffff8adf68a0
RBP: ffffc9000555f5b8 R08: dffffc0000000000 R09: 1ffffffff2161e48
R10: dffffc0000000000 R11: fffffbfff2161e49 R12: 0000000000000001
R13: 1ffff92000aabea0 R14: 0000000000000246 R15: dffffc0000000000
 rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
 rcu_read_lock include/linux/rcupdate.h:791 [inline]
 is_bpf_text_address+0x43/0x2a0 kernel/bpf/core.c:736
 kernel_text_address+0x9c/0xd0 kernel/extable.c:125
 __kernel_text_address+0x9/0x30 kernel/extable.c:79
 unwind_get_return_address+0x49/0x80 arch/x86/kernel/unwind_orc.c:323
 arch_stack_walk+0xf2/0x140 arch/x86/kernel/stacktrace.c:26
 stack_trace_save+0xa6/0xf0 kernel/stacktrace.c:122
 kasan_save_stack mm/kasan/common.c:46 [inline]
 kasan_set_track+0x4b/0x70 mm/kasan/common.c:53
 kasan_save_free_info+0x27/0x40 mm/kasan/generic.c:516
 ____kasan_slab_free+0x126/0x1f0 mm/kasan/common.c:237
 kasan_slab_free include/linux/kasan.h:177 [inline]
 slab_free_hook mm/slub.c:1729 [inline]
 slab_free_freelist_hook+0x133/0x1b0 mm/slub.c:1755
 slab_free mm/slub.c:3687 [inline]
 __kmem_cache_free+0xb6/0x200 mm/slub.c:3700
 kobject_uevent_env+0x35b/0x890 lib/kobject_uevent.c:640
 driver_register+0x3e2/0x430 drivers/base/driver.c:254
 usb_gadget_register_driver_owner+0xf5/0x260 drivers/usb/gadget/udc/core.c:1730
 raw_ioctl_run drivers/usb/gadget/legacy/raw_gadget.c:549 [inline]
 raw_ioctl+0x13a0/0x3cd0 drivers/usb/gadget/legacy/raw_gadget.c:1262
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:870 [inline]
 __se_sys_ioctl+0xfa/0x170 fs/ioctl.c:856
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f62c3d9ddeb
Code: 00 48 89 44 24 18 31 c0 48 8d 44 24 60 c7 04 24 10 00 00 00 48 89 44 24 08 48 8d 44 24 20 48 89 44 24 10 b8 10 00 00 00 0f 05 <89> c2 3d 00 f0 ff ff 77 1c 48 8b 44 24 18 64 48 2b 04 25 28 00 00
RSP: 002b:00007f62c4c45f00 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00007f62c3d9ddeb
RDX: 0000000000000000 RSI: 0000000000005501 RDI: 0000000000000003
RBP: 00007f62c4c46fd0 R08: 0000000000000001 R09: 00000000ffffffff
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00002000000012c0 R14: 0000000000000000 R15: 0000000000000000
 </TASK>
rcu: rcu_preempt kthread timer wakeup didn't happen for 10234 jiffies! g61205 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402
rcu: 	Possible timer handling issue on cpu=0 timer-softirq=24117
rcu: rcu_preempt kthread starved for 10235 jiffies! g61205 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->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:I stack:27920 pid:16    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5246 [inline]
 __schedule+0x107f/0x4030 kernel/sched/core.c:6563
 schedule+0xb9/0x180 kernel/sched/core.c:6639
 schedule_timeout+0x184/0x2d0 kernel/time/timer.c:2168
 rcu_gp_fqs_loop+0x303/0x1350 kernel/rcu/tree.c:1706
 rcu_gp_kthread+0x99/0x3b0 kernel/rcu/tree.c:1905
 kthread+0x29d/0x330 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
CPU: 0 PID: 9412 Comm: syz.0.1638 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:csd_lock_wait kernel/smp.c:424 [inline]
RIP: 0010:smp_call_function_many_cond+0x1148/0x1250 kernel/smp.c:998
Code: 41 8b 1f 89 de 83 e6 01 31 ff e8 53 02 0b 00 83 e3 01 48 bb 00 00 00 00 00 fc ff df 75 0a e8 df fe 0a 00 e9 34 ff ff ff f3 90 <41> 0f b6 04 1c 84 c0 75 14 41 f7 07 01 00 00 00 0f 84 17 ff ff ff
RSP: 0018:ffffc90004ebfc20 EFLAGS: 00000246
RAX: ffffffff81773423 RBX: dffffc0000000000 RCX: 0000000000080000
RDX: ffffc900057c1000 RSI: 000000000007ffff RDI: 0000000000080000
RBP: ffffc90004ebfd80 R08: ffffffff90b0f36f R09: 1ffffffff2161e6d
R10: dffffc0000000000 R11: fffffbfff2161e6e R12: 1ffff110171e820d
R13: ffff8880b8e3bd80 R14: 0000000000000001 R15: ffff8880b8f41068
FS:  00007f6ad058e6c0(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b2fc23ffc CR3: 0000000079929000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 on_each_cpu_cond_mask+0x3b/0x80 kernel/smp.c:1165
 on_each_cpu include/linux/smp.h:71 [inline]
 hardware_enable_all+0x7a/0x120 virt/kvm/kvm_main.c:5167
 kvm_create_vm virt/kvm/kvm_main.c:1223 [inline]
 kvm_dev_ioctl_create_vm virt/kvm/kvm_main.c:5013 [inline]
 kvm_dev_ioctl+0x112a/0x17f0 virt/kvm/kvm_main.c:5055
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:870 [inline]
 __se_sys_ioctl+0xfa/0x170 fs/ioctl.c:856
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f6acf79e159
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:00007f6ad058e028 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f6acfa25fa0 RCX: 00007f6acf79e159
RDX: 0000000000000000 RSI: 000000000000ae01 RDI: 0000000000000003
RBP: 00007f6acf83506b R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f6acfa26038 R14: 00007f6acfa25fa0 R15: 00007ffc960c9ca8
 </TASK>

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/09/27 11:15 linux-6.1.y 1a8763b93150 a3c7249d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in raw_ioctl
* Struck through repros no longer work on HEAD.