INFO: rcu detected stall in kcov_ioctl (4)

Status: upstream: reported on 2026/10/04 13:36
Reported-by: syzbot+e1a6476ecb1f6940f89d@syzkaller.appspotmail.com
First crash: 5d21h, last: 5d21h
▶ ▼ Similar bugs (7)
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 823d 826d 0/3 auto-obsoleted due to no activity on 2024/10/16 15:00
upstream INFO: rcu detected stall in kcov_ioctl (3) prio:high mm 1 32 19d 184d 0/29 upstream: reported on 2026/04/08 23:31
linux-6.1 INFO: rcu detected stall in kcov_ioctl (2) 1 4 348d 517d 0/3 auto-obsoleted due to no activity on 2026/02/03 14:39
linux-6.1 INFO: rcu detected stall in kcov_ioctl (3) 1 1 172d 172d 0/3 auto-obsoleted due to no activity on 2026/07/30 00:51
upstream INFO: rcu detected stall in kcov_ioctl mm 1 1 2503d 2503d 0/29 closed as invalid on 2019/12/04 14:04
upstream INFO: rcu detected stall in kcov_ioctl (2) mm 1 78 642d 802d 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 873d 906d 0/2 auto-obsoleted due to no activity on 2024/08/17 12:17

Sample crash report:
rcu: INFO: rcu_preempt detected expedited stalls on CPUs/tasks: { 0-.... } 2671 jiffies s: 154529 root: 0x1/.
rcu: blocking rcu_node structures (internal RCU debug):
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 1970 Comm: syz-executor Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026
RIP: 0010:check_region_inline mm/kasan/generic.c:172 [inline]
RIP: 0010:kasan_check_range+0x1f/0x290 mm/kasan/generic.c:189
Code: 00 cc cc 00 00 cc cc 00 00 cc cc b0 01 48 85 f6 0f 84 ac 01 00 00 55 41 57 41 56 41 54 53 49 89 f8 49 01 f0 0f 82 0e 02 00 00 <49> 89 f8 49 c1 e8 2f 41 81 f8 ff ff 01 00 0f 82 fa 01 00 00 49 bc
RSP: 0018:ffffc90000007370 EFLAGS: 00000086
RAX: 0000000000000001 RBX: 0000000000000016 RCX: ffffffff81640c12
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff90b33240
RBP: ffffc900000075e8 R08: ffffffff90b33248 R09: 1ffffffff2166648
R10: dffffc0000000000 R11: fffffbfff2166649 R12: ffff8880276246c4
R13: ffff888027623c00 R14: 0000000000000002 R15: ffff888027624750
FS:  00005555911c7500(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f9bd5958060 CR3: 000000008c29d000 CR4: 00000000003506f0
DR0: 0000200000000300 DR1: 0000200000000300 DR2: 0000200000000300
DR3: 0000200000000300 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
 <IRQ>
 instrument_atomic_read include/linux/instrumented.h:72 [inline]
 _test_bit include/asm-generic/bitops/instrumented-non-atomic.h:141 [inline]
 hlock_class kernel/locking/lockdep.c:228 [inline]
 check_wait_context kernel/locking/lockdep.c:4802 [inline]
 __lock_acquire+0x712/0x7ea0 kernel/locking/lockdep.c:5121
 lock_acquire+0x1bc/0x4a0 kernel/locking/lockdep.c:5790
 rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
 rcu_read_lock_sched include/linux/rcupdate.h:883 [inline]
 pfn_valid include/linux/mmzone.h:1857 [inline]
 __virt_addr_valid+0x1a5/0x540 arch/x86/mm/physaddr.c:65
 kasan_addr_to_slab+0x9/0xc0 mm/kasan/common.c:36
 __kasan_record_aux_stack+0xf/0xc0 mm/kasan/generic.c:471
 irq_work_queue_on+0x10f/0x260 kernel/irq_work.c:140
 rcu_read_unlock_special+0x3c9/0x510 kernel/rcu/tree_plugin.h:678
 __rcu_read_unlock+0x78/0xd0 kernel/rcu/tree_plugin.h:426
 rcu_read_unlock include/linux/rcupdate.h:823 [inline]
 trace_call_bpf+0x5bb/0x6b0 kernel/trace/bpf_trace.c:137
 perf_trace_run_bpf_submit+0x79/0x1c0 kernel/events/core.c:10037
 perf_trace_preemptirq_template+0x268/0x320 include/trace/events/preemptirq.h:14
 trace_irq_enable_rcuidle+0xd3/0x140 include/trace/events/preemptirq.h:40
 trace_hardirqs_on+0x24/0x40 kernel/trace/trace_preemptirq.c:44
 asm_sysvec_irq_work+0x16/0x20 arch/x86/include/asm/idtentry.h:728
RIP: 0010:rcu_read_unlock_special+0x7f/0x510 kernel/rcu/tree_plugin.h:685
Code: eb 03 48 b8 f1 f1 f1 f1 f8 f2 f2 f2 4a 89 04 2b 42 c7 44 2b 08 f8 f3 f3 f3 65 44 8b 35 d2 68 95 7e 41 f7 c6 00 00 f0 00 74 40 <48> c7 44 24 40 0e 36 e0 45 4a c7 04 2b 00 00 00 00 42 c7 44 2b 08
RSP: 0018:ffffc90000007c40 EFLAGS: 00000206
RAX: 99345dc4c7544400 RBX: 1ffff92000000f90 RCX: 99345dc4c7544400
RDX: dffffc0000000000 RSI: ffffffff8a8c18a0 RDI: ffffffff8adf6de0
RBP: ffffc90000007d30 R08: ffff8880b8e357cb R09: 1ffff110171c6af9
R10: dffffc0000000000 R11: ffffed10171c6afa R12: 0000000000000246
R13: dffffc0000000000 R14: ffff8880b8e3bb00 R15: 0000000000000001
 __rcu_read_unlock+0x78/0xd0 kernel/rcu/tree_plugin.h:426
 rcu_read_unlock include/linux/rcupdate.h:823 [inline]
 rebalance_domains+0x86f/0x9d0 kernel/sched/fair.c:11061
 handle_softirqs+0x291/0x910 kernel/softirq.c:596
 __do_softirq kernel/softirq.c:630 [inline]
 invoke_softirq kernel/softirq.c:470 [inline]
 __irq_exit_rcu+0x13b/0x230 kernel/softirq.c:679
 irq_exit_rcu+0x5/0x20 kernel/softirq.c:691
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1118 [inline]
 sysvec_apic_timer_interrupt+0xa0/0xc0 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:check_kcov_mode kernel/kcov.c:189 [inline]
RIP: 0010:__sanitizer_cov_trace_pc+0x32/0x60 kernel/kcov.c:212
Code: b4 28 80 7e 65 8b 15 b5 28 80 7e 81 e2 00 01 ff 00 74 11 81 fa 00 01 00 00 75 35 83 b9 1c 16 00 00 00 74 2c 8b 91 f8 15 00 00 <83> fa 02 75 21 48 8b 91 00 16 00 00 48 8b 32 48 8d 7e 01 8b 89 fc
RSP: 0018:ffffc9000ce57c40 EFLAGS: 00000246
RAX: ffffffff81d0b6e2 RBX: 0000000000000000 RCX: ffff888027623c00
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000041
RBP: 0000000000000000 R08: ffff888027623c07 R09: 1ffff11004ec4780
R10: dffffc0000000000 R11: ffffed1004ec4781 R12: ffffe8ffffffffff
R13: 0000000000000000 R14: 0000000000000000 R15: dffffc0000000000
 get_task_policy mm/mempolicy.c:171 [inline]
 alloc_pages+0x2b2/0x740 mm/mempolicy.c:2270
 vm_area_alloc_pages mm/vmalloc.c:3059 [inline]
 __vmalloc_area_node mm/vmalloc.c:3128 [inline]
 __vmalloc_node_range+0x94a/0x1380 mm/vmalloc.c:3300
 vmalloc_user+0x70/0x80 mm/vmalloc.c:3454
 kcov_ioctl+0x54/0x610 kernel/kcov.c:715
 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: 0033:0x7f32cf99ddeb
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:00007fff4ed56b10 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000080000 RCX: 00007f32cf99ddeb
RDX: 0000000000080000 RSI: ffffffff80086301 RDI: 00000000000000df
RBP: 00007f32cfc266c8 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000003 R14: 00007fff4ed56dc8 R15: 0000000000000000
 </TASK>

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/10/04 13:36 linux-6.1.y a500ba24937a 57bbd979 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-perf INFO: rcu detected stall in kcov_ioctl
* Struck through repros no longer work on HEAD.