syzbot

 sign-in | mailing list | source | docs
🐞 Open [777]
🐞 Fixed [129]
🐞 Invalid [851]
⬇ Missing Backports [72]
≡ Crashes
Kernel Health Bugs/Month Bug Lifetimes Fuzzing
💬 Send us feedback

INFO: rcu detected stall in kcov_ioctl (2)

Status: upstream: reported on 2025/05/11 07:59
Reported-by: syzbot+12a99337276c7bf42c3d@syzkaller.appspotmail.com
First crash: 114d, last: 44d
▶ ▼ Similar bugs (4)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.1 INFO: rcu detected stall in kcov_ioctl 1 2 420d 423d 0/3 auto-obsoleted due to no activity on 2024/10/16 15:00
upstream INFO: rcu detected stall in kcov_ioctl mm 1 1 2100d 2100d 0/29 closed as invalid on 2019/12/04 14:04
upstream INFO: rcu detected stall in kcov_ioctl (2) mm 1 78 239d 399d 0/29 auto-obsoleted due to no activity on 2025/03/17 09:34
android-5-15 BUG: soft lockup in kcov_ioctl 1 8 471d 503d 0/2 auto-obsoleted due to no activity on 2024/08/17 12:17

Sample crash report:
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P10311/1:b..l P10291/1:b..l
	(detected by 1, t=10502 jiffies, g=58053, q=169 ncpus=2)
task:syz-executor    state:R  running task     stack:24352 pid:10291 ppid:4253   flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5244 [inline]
 __schedule+0x10e9/0x40d0 kernel/sched/core.c:6561
 preempt_schedule_irq+0xb1/0x150 kernel/sched/core.c:6873
 irqentry_exit+0x63/0x70 kernel/entry/common.c:439
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691
RIP: 0010:debug_lockdep_rcu_enabled+0x0/0x30 kernel/rcu/update.c:279
Code: 66 09 04 00 75 e8 48 c7 c7 00 03 8c 8a 48 c7 c6 e0 26 8c 8a e8 71 d1 36 f7 0f 0b eb d1 00 00 cc cc 00 00 cc cc 00 00 cc cc 00 <31> c0 83 3d 47 32 09 04 00 74 1d 83 3d d2 65 09 04 00 74 14 65 48
RSP: 0018:ffffc900033876a8 EFLAGS: 00000292
RAX: c5ba478b9910e000 RBX: 00007fec4d58e5ab RCX: c5ba478b9910e000
RDX: 0000000000000000 RSI: ffffffff8a8c15e0 RDI: ffffffff8adef260
RBP: 0000000000000001 R08: dffffc0000000000 R09: fffffbfff215ba49
R10: fffffbfff215ba49 R11: 1ffffffff215ba48 R12: ffff888030f0bb80
R13: 1ffff92000670f14 R14: 00007fec4d58e5ab R15: 1ffff92000670ef2
 rcu_read_lock include/linux/rcupdate.h:792 [inline]
 is_bpf_text_address+0x4c/0x2a0 kernel/bpf/core.c:735
 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+0x98/0xe0 kernel/stacktrace.c:122
 save_stack+0xf3/0x1e0 mm/page_owner.c:127
 __set_page_owner+0x19/0x60 mm/page_owner.c:190
 set_page_owner include/linux/page_owner.h:31 [inline]
 post_alloc_hook+0x173/0x1a0 mm/page_alloc.c:2532
 prep_new_page mm/page_alloc.c:2539 [inline]
 get_page_from_freelist+0x1a26/0x1ac0 mm/page_alloc.c:4328
 __alloc_pages+0x1df/0x4e0 mm/page_alloc.c:5614
 vm_area_alloc_pages mm/vmalloc.c:2994 [inline]
 __vmalloc_area_node mm/vmalloc.c:3063 [inline]
 __vmalloc_node_range+0x959/0x1390 mm/vmalloc.c:3235
 vmalloc_user+0x70/0x80 mm/vmalloc.c:3389
 kcov_ioctl+0x54/0x640 kernel/kcov.c:713
 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:51 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fec4d58e5ab
RSP: 002b:00007fffb9976f60 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000080000 RCX: 00007fec4d58e5ab
RDX: 0000000000080000 RSI: ffffffff80086301 RDI: 00000000000000dd
RBP: 00007fec4d7b6498 R08: 00000000000000da R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000003 R14: 0000000000000009 R15: 0000000000000000
 </TASK>
task:syz.4.1275      state:R  running task     stack:25728 pid:10311 ppid:4266   flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5244 [inline]
 __schedule+0x10e9/0x40d0 kernel/sched/core.c:6561
 preempt_schedule_common+0x82/0xd0 kernel/sched/core.c:6730
 preempt_schedule+0xa7/0xb0 kernel/sched/core.c:6754
 preempt_schedule_thunk+0x16/0x18 arch/x86/entry/thunk_64.S:34
 __local_bh_enable_ip+0x13b/0x1b0 kernel/softirq.c:428
 local_bh_enable include/linux/bottom_half.h:33 [inline]
 xdp_test_run_batch net/bpf/test_run.c:340 [inline]
 bpf_test_run_xdp_live+0x173a/0x1970 net/bpf/test_run.c:362
 bpf_prog_test_run_xdp+0x6f1/0xe50 net/bpf/test_run.c:1390
 bpf_prog_test_run+0x31e/0x390 kernel/bpf/syscall.c:3685
 __sys_bpf+0x593/0x6d0 kernel/bpf/syscall.c:5038
 __do_sys_bpf kernel/bpf/syscall.c:5124 [inline]
 __se_sys_bpf kernel/bpf/syscall.c:5122 [inline]
 __x64_sys_bpf+0x78/0x90 kernel/bpf/syscall.c:5122
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f426878e9a9
RSP: 002b:00007f4269667038 EFLAGS: 00000246 ORIG_RAX: 0000000000000141
RAX: ffffffffffffffda RBX: 00007f42689b5fa0 RCX: 00007f426878e9a9
RDX: 0000000000000048 RSI: 0000200000000600 RDI: 000000000000000a
RBP: 00007f4268810d69 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f42689b5fa0 R15: 00007fff56ec2108
 </TASK>
rcu: rcu_preempt kthread starved for 543 jiffies! g58053 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:26912 pid:16    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5244 [inline]
 __schedule+0x10e9/0x40d0 kernel/sched/core.c:6561
 preempt_schedule_common+0x82/0xd0 kernel/sched/core.c:6730
 preempt_schedule+0xa7/0xb0 kernel/sched/core.c:6754
 preempt_schedule_thunk+0x16/0x18 arch/x86/entry/thunk_64.S:34
 __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:152 [inline]
 _raw_spin_unlock_irqrestore+0xf6/0x100 kernel/locking/spinlock.c:194
 __mod_timer+0x8ee/0xd20 kernel/time/timer.c:1118
 schedule_timeout+0x157/0x280 kernel/time/timer.c:1964
 rcu_gp_fqs_loop+0x2f2/0x1310 kernel/rcu/tree.c:1706
 rcu_gp_kthread+0x95/0x380 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:
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 10302 Comm: syz.2.1272 Not tainted 6.1.146-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
RIP: 0010:trace_lock_release include/trace/events/lock.h:69 [inline]
RIP: 0010:lock_release+0xcd/0x910 kernel/locking/lockdep.c:5673
Code: 59 de bb 0c 0f 83 22 05 00 00 41 89 de c1 eb 06 48 8d 3c dd e8 48 1f 8e be 08 00 00 00 e8 2b 78 6d 00 4c 0f a3 35 2b dc bb 0c <73> 0d e8 cc 99 07 00 84 c0 0f 84 29 05 00 00 48 c7 c0 a4 7d 1f 8e
RSP: 0018:ffffc90000007d40 EFLAGS: 00000057
RAX: 0000000000000001 RBX: 0000000000000000 RCX: ffffffff81636cb5
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff8e1f48e8
RBP: ffffc90000007e50 R08: dffffc0000000000 R09: fffffbfff1c3e91e
R10: fffffbfff1c3e91e R11: 1ffffffff1c3e91d R12: ffffffff815057fa
R13: dffffc0000000000 R14: 0000000000000000 R15: 1ffff92000000fb4
FS:  00007f101f7636c0(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f101f763000 CR3: 000000001d702000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <IRQ>
 rcu_lock_release include/linux/rcupdate.h:355 [inline]
 rcu_read_unlock include/linux/rcupdate.h:824 [inline]
 group_send_sig_info+0x178/0x250 kernel/signal.c:1446
 do_bpf_send_signal+0x7b/0x150 kernel/trace/bpf_trace.c:840
 irq_work_single+0xd1/0x230 kernel/irq_work.c:211
 irq_work_run_list kernel/irq_work.c:242 [inline]
 irq_work_run+0x152/0x2e0 kernel/irq_work.c:251
 __sysvec_irq_work+0xba/0x350 arch/x86/kernel/irq_work.c:22
 instr_sysvec_irq_work arch/x86/kernel/irq_work.c:17 [inline]
 sysvec_irq_work+0x98/0xc0 arch/x86/kernel/irq_work.c:17
 </IRQ>
 <TASK>
 asm_sysvec_irq_work+0x16/0x20 arch/x86/include/asm/idtentry.h:728
RIP: 0010:arch_static_branch arch/x86/include/asm/jump_label.h:27 [inline]
RIP: 0010:static_key_false include/linux/jump_label.h:207 [inline]
RIP: 0010:native_write_msr arch/x86/include/asm/msr.h:147 [inline]
RIP: 0010:wrmsr arch/x86/include/asm/msr.h:254 [inline]
RIP: 0010:native_apic_msr_write+0x35/0x50 arch/x86/include/asm/apic.h:206
Code: 74 2a 83 ff 30 74 25 eb 10 81 ff d0 00 00 00 74 1b 81 ff e0 00 00 00 74 13 c1 ef 04 81 c7 00 08 00 00 89 f9 89 f0 31 d2 0f 30 <66> 90 c3 89 f6 31 d2 e9 1f 46 f7 02 66 2e 0f 1f 84 00 00 00 00 00
RSP: 0018:ffffc9000378fcb0 EFLAGS: 00000246
RAX: 00000000000000f6 RBX: ffffffff8c5e0b88 RCX: 000000000000083f
RDX: 0000000000000000 RSI: 00000000000000f6 RDI: 000000000000083f
RBP: 0000000000000000 R08: dffffc0000000000 R09: fffff520006f1f85
R10: fffff520006f1f85 R11: 1ffff920006f1f84 R12: ffff8880b8e33e01
R13: dffffc0000000000 R14: dffffc0000000000 R15: 0000000000000020
 arch_irq_work_raise+0x82/0xd0 arch/x86/kernel/irq_work.c:31
 irq_work_queue+0x95/0x140 kernel/irq_work.c:114
 bpf_send_signal_common+0x2b2/0x420 kernel/trace/bpf_trace.c:879
 ____bpf_send_signal kernel/trace/bpf_trace.c:888 [inline]
 bpf_send_signal+0x15/0x20 kernel/trace/bpf_trace.c:886
 bpf_prog_7ba5217f62dcd359+0x38/0x3c
 bpf_dispatcher_nop_func include/linux/bpf.h:1001 [inline]
 __bpf_prog_run include/linux/filter.h:603 [inline]
 bpf_prog_run include/linux/filter.h:610 [inline]
 __bpf_trace_run kernel/trace/bpf_trace.c:2285 [inline]
 bpf_trace_run2+0x1cd/0x3b0 kernel/trace/bpf_trace.c:2324
 __bpf_trace_sys_enter+0x60/0x70 include/trace/events/syscalls.h:18
 trace_sys_enter+0x6b/0x80 include/trace/events/syscalls.h:18
 syscall_trace_enter+0xf0/0x150 kernel/entry/common.c:81
 do_syscall_64+0x24/0xa0 arch/x86/entry/common.c:77
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f101e92ab89
Code: 64 c7 00 16 00 00 00 b8 ff ff ff ff c3 0f 1f 40 00 90 66 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 c7 c0 0f 00 00 00 0f 05 <0f> 1f 80 00 00 00 00 48 81 ec 48 01 00 00 49 89 d0 64 48 8b 04 25
RSP: 002b:00007f101f762b40 EFLAGS: 00000246 ORIG_RAX: 000000000000000f
RAX: ffffffffffffffda RBX: 00007f101ebb6088 RCX: 00007f101e92ab89
RDX: 00007f101f762b40 RSI: 00007f101f762c70 RDI: 0000000000000011
RBP: 00007f101ebb6080 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f101ebb608c
R13: 0000000000000000 R14: 00007fff3de8caa0 R15: 00007fff3de8cb88
 </TASK>
vkms_vblank_simulate: vblank timer overrun

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/07/20 09:46 linux-6.1.y 3369c6df2fae 7117feec .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in kcov_ioctl
2025/05/11 07:58 linux-6.1.y 02b72ccb5f9d 77908e5f .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in kcov_ioctl
* Struck through repros no longer work on HEAD.