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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: 169d, last: 18h36m
▶ ▼ 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 475d 478d 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 2155d 2154d 0/29 closed as invalid on 2019/12/04 14:04
upstream INFO: rcu detected stall in kcov_ioctl (2) mm 1 78 293d 454d 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 525d 558d 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): P5927/1:b..l
	(detected by 1, t=10502 jiffies, g=17309, q=225 ncpus=2)
task:syz-executor    state:R  running task     stack:24352 pid:5927  ppid:4256   flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5244 [inline]
 __schedule+0x10ec/0x40b0 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:lock_acquire+0x20f/0x490 kernel/locking/lockdep.c:5666
Code: 00 9c 8f 84 24 80 00 00 00 f6 84 24 81 00 00 00 02 0f 85 f5 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 66 43 c7 44 3d 09 00 00 43 c6 44 3d 0b
RSP: 0018:ffffc90003ff7580 EFLAGS: 00000206
RAX: 0000000000000001 RBX: 0000000000000000 RCX: f39977782514de00
RDX: 0000000000000000 RSI: ffffffff8a8c1700 RDI: ffffffff8adef3a0
RBP: ffffc90003ff7698 R08: dffffc0000000000 R09: fffffbfff215c449
R10: fffffbfff215c449 R11: 1ffffffff215c448 R12: 0000000000000000
R13: 1ffff920007feebc 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: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:3002 [inline]
 __vmalloc_area_node mm/vmalloc.c:3071 [inline]
 __vmalloc_node_range+0x959/0x1390 mm/vmalloc.c:3243
 vmalloc_user+0x70/0x80 mm/vmalloc.c:3397
 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: 0033:0x7f788cf8ebcb
RSP: 002b:00007ffff44fc0f0 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000080000 RCX: 00007f788cf8ebcb
RDX: 0000000000080000 RSI: ffffffff80086301 RDI: 00000000000000df
RBP: 00007f788d1e66c8 R08: 00000000000000da R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000003 R14: 0000000000000009 R15: 0000000000000000
 </TASK>
rcu: rcu_preempt kthread starved for 10394 jiffies! g17309 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=1
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:27840 pid:16    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5244 [inline]
 __schedule+0x10ec/0x40b0 kernel/sched/core.c:6561
 schedule+0xb9/0x180 kernel/sched/core.c:6637
 schedule_timeout+0x15c/0x280 kernel/time/timer.c:1965
 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:
CPU: 1 PID: 5881 Comm: syz.4.407 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
RIP: 0010:native_safe_halt arch/x86/include/asm/irqflags.h:51 [inline]
RIP: 0010:arch_safe_halt arch/x86/include/asm/irqflags.h:89 [inline]
RIP: 0010:kvm_wait+0x141/0x190 arch/x86/kernel/kvm.c:1064
Code: 89 df 48 89 f8 48 c1 e8 03 42 0f b6 04 30 84 c0 75 47 0f b6 1f e8 bf 3d 4f 00 44 38 e3 75 10 66 90 0f 00 2d 51 74 51 09 fb f4 <e9> 33 ff ff ff fb e9 2d ff ff ff e8 6f d0 df 08 89 f9 80 e1 07 38
RSP: 0018:ffffc90003bf75a0 EFLAGS: 00000246
RAX: ebbfb57f81f50b00 RBX: 0000000000000003 RCX: ebbfb57f81f50b00
RDX: dffffc0000000000 RSI: ffffffff8a8c0580 RDI: ffffffff8adef3a0
RBP: ffffc90003bf7650 R08: dffffc0000000000 R09: fffffbfff215c450
R10: fffffbfff215c450 R11: 1ffffffff215c44f R12: 0000000000000003
R13: ffff8880b8f3b914 R14: dffffc0000000000 R15: 1ffff9200077eeb4
FS:  0000000000000000(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000563c9779d078 CR3: 000000005b6d5000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600
Call Trace:
 <TASK>
 pv_wait arch/x86/include/asm/paravirt.h:603 [inline]
 pv_wait_head_or_lock kernel/locking/qspinlock_paravirt.h:470 [inline]
 __pv_queued_spin_lock_slowpath+0x616/0x9c0 kernel/locking/qspinlock.c:511
 pv_queued_spin_lock_slowpath arch/x86/include/asm/paravirt.h:591 [inline]
 queued_spin_lock_slowpath+0x43/0x50 arch/x86/include/asm/qspinlock.h:51
 queued_spin_lock include/asm-generic/qspinlock.h:114 [inline]
 do_raw_spin_lock+0x217/0x280 kernel/locking/spinlock_debug.c:115
 spin_lock include/linux/spinlock.h:351 [inline]
 dentry_kill+0xe6/0x290 fs/dcache.c:742
 dput+0xfa/0x1d0 fs/dcache.c:918
 __fput+0x5e0/0x920 fs/file_table.c:328
 task_work_run+0x1ca/0x250 kernel/task_work.c:203
 exit_task_work include/linux/task_work.h:39 [inline]
 do_exit+0x93e/0x2400 kernel/exit.c:880
 do_group_exit+0x217/0x2d0 kernel/exit.c:1022
 get_signal+0x1272/0x1350 kernel/signal.c:2871
 arch_do_signal_or_restart+0xb7/0x1240 arch/x86/kernel/signal.c:871
 exit_to_user_mode_loop+0x70/0x110 kernel/entry/common.c:174
 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:210
 __syscall_exit_to_user_mode_work kernel/entry/common.c:292 [inline]
 syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:303
 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:87
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f21e3b8efc9
Code: Unable to access opcode bytes at 0x7f21e3b8ef9f.
RSP: 002b:00007f21e499cfe8 EFLAGS: 00000206 ORIG_RAX: 0000000000000038
RAX: ffffffffffffffff RBX: 00007f21e3de6180 RCX: 00007f21e3b8efc9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 00000000a49a4400
RBP: 00007f21e3c11f91 R08: ffffffffff600000 R09: ffffffffff600000
R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000000
R13: 00007f21e3de6218 R14: 00007f21e3de6180 R15: 00007ffcb7829cb8
 </TASK>

Crashes (4):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/10/26 14:38 linux-6.1.y 8e6e2188d949 c0460fcd .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-perf INFO: rcu detected stall in kcov_ioctl
2025/09/26 13:49 linux-6.1.y 7b34dc04e4ff 0abd0691 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in kcov_ioctl
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.