syzbot

 sign-in | mailing list | source | docs
🐞 Open [822]
🐞 Fixed [86]
🐞 Invalid [1164]
⬇ Missing Backports [135]
≡ Crashes
Kernel Health Bugs/Month Bug Lifetimes Fuzzing
💬 Send us feedback

INFO: rcu detected stall in kcov_mmap

Status: auto-obsoleted due to no activity on 2024/12/01 17:49
Reported-by: syzbot+d83f3d85e23b7dbf1bc7@syzkaller.appspotmail.com
First crash: 585d, last: 493d
▶ ▼ Similar bugs (5)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: rcu detected stall in kcov_mmap (2) mm 1 18 252d 574d 0/29 auto-obsoleted due to no activity on 2025/07/20 12:30
upstream INFO: rcu detected stall in kcov_mmap mm 1 1 685d 685d 0/29 auto-obsoleted due to no activity on 2024/05/13 16:16
linux-6.6 INFO: rcu detected stall in kcov_mmap 1 3 11d 35d 0/2 upstream: reported on 2025/11/25 09:58
linux-6.1 INFO: rcu detected stall in kcov_mmap 1 1 524d 524d 0/3 auto-obsoleted due to no activity on 2024/11/01 05:49
upstream BUG: soft lockup in kcov_mmap mm 1 1 1725d 1721d 0/29 auto-closed as invalid on 2021/07/09 11:42

Sample crash report:
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P3806/1:b..l P12009/1:b..l
	(detected by 0, t=10502 jiffies, g=67473, q=177)
task:syz.2.1537      state:R  running task     stack:24000 pid:12009 ppid: 11159 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5027 [inline]
 __schedule+0x12c4/0x45b0 kernel/sched/core.c:6373
 preempt_schedule_irq+0xf7/0x1c0 kernel/sched/core.c:6777
 irqentry_exit+0x53/0x80 kernel/entry/common.c:432
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:638
RIP: 0010:latch_tree_find include/linux/rbtree_latch.h:208 [inline]
RIP: 0010:bpf_ksym_find kernel/bpf/core.c:688 [inline]
RIP: 0010:is_bpf_text_address+0x184/0x260 kernel/bpf/core.c:722
Code: 5d f3 ff 48 83 c3 08 48 89 d8 48 c1 e8 03 42 80 3c 20 00 74 08 48 89 df e8 e9 25 3d 00 48 8b 1b 48 85 db 74 0a e8 0c 5d f3 ff <e9> 5f ff ff ff e8 02 5d f3 ff 31 ed eb 0e e8 f9 5c f3 ff 31 ed eb
RSP: 0018:ffffc90003447560 EFLAGS: 00000293
RAX: ffffffff818d0494 RBX: ffff88801f7331e8 RCX: ffff888079b8bb80
RDX: 0000000000000000 RSI: 00007f1a95e16eb3 RDI: ffffffffa002c000
RBP: 0000000000000000 R08: ffffffff818d0424 R09: fffffbfff1f8e219
R10: 0000000000000000 R11: dffffc0000000001 R12: dffffc0000000000
R13: 0000000000000000 R14: 00007f1a95e16eb3 R15: ffffffffa002c000
 kernel_text_address kernel/extable.c:151 [inline]
 __kernel_text_address+0x94/0x100 kernel/extable.c:105
 unwind_get_return_address+0x49/0x80 arch/x86/kernel/unwind_orc.c:323
 arch_stack_walk+0xf3/0x140 arch/x86/kernel/stacktrace.c:26
 stack_trace_save+0x113/0x1c0 kernel/stacktrace.c:122
 save_stack+0xf6/0x1e0 mm/page_owner.c:119
 __reset_page_owner+0x52/0x180 mm/page_owner.c:140
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1340 [inline]
 free_pcp_prepare mm/page_alloc.c:1391 [inline]
 free_unref_page_prepare+0xc34/0xcf0 mm/page_alloc.c:3317
 free_unref_page+0x95/0x2d0 mm/page_alloc.c:3396
 __vunmap+0x8d4/0xa20 mm/vmalloc.c:2621
 kcov_mmap+0x8f/0x120 kernel/kcov.c:498
 call_mmap include/linux/fs.h:2177 [inline]
 mmap_region+0x10e7/0x1670 mm/mmap.c:1791
 do_mmap+0x78d/0xe00 mm/mmap.c:1575
 vm_mmap_pgoff+0x1ca/0x2d0 mm/util.c:551
 ksys_mmap_pgoff+0x559/0x780 mm/mmap.c:1624
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f1a95e16eb3
RSP: 002b:00007fff3a538068 EFLAGS: 00000246 ORIG_RAX: 0000000000000009
RAX: ffffffffffffffda RBX: 00007f1a95fb32a0 RCX: 00007f1a95e16eb3
RDX: 0000000000000003 RSI: 0000000000200000 RDI: 00007f1a94030000
RBP: 00007f1a95fb3208 R08: 00000000000000db R09: 0000000000000000
R10: 0000000000000011 R11: 0000000000000246 R12: 0000000000000003
R13: 00007f1a95fb3208 R14: 0000000000000003 R15: 000000000000031a
 </TASK>
task:kworker/u4:10   state:R  running task     stack:20280 pid: 3806 ppid:     2 flags:0x00004000
Workqueue: bat_events batadv_nc_worker
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5027 [inline]
 __schedule+0x12c4/0x45b0 kernel/sched/core.c:6373
 preempt_schedule_irq+0xf7/0x1c0 kernel/sched/core.c:6777
 irqentry_exit+0x53/0x80 kernel/entry/common.c:432
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:638
RIP: 0010:lock_acquire+0x252/0x4f0 kernel/locking/lockdep.c:5627
Code: 2b 00 74 08 4c 89 f7 e8 4c 7b 67 00 f6 44 24 61 02 0f 85 84 01 00 00 41 f7 c7 00 02 00 00 74 01 fb 48 c7 44 24 40 0e 36 e0 45 <4b> c7 44 25 00 00 00 00 00 43 c7 44 25 09 00 00 00 00 43 c7 44 25
RSP: 0018:ffffc900035c7a80 EFLAGS: 00000206
RAX: 0000000000000001 RBX: 1ffff920006b8f5c RCX: 1ffff920006b8efc
RDX: dffffc0000000000 RSI: ffffffff8a8b3cc0 RDI: ffffffff8ad8f7c0
RBP: ffffc900035c7bd8 R08: dffffc0000000000 R09: fffffbfff1f8e219
R10: 0000000000000000 R11: dffffc0000000001 R12: 1ffff920006b8f58
R13: dffffc0000000000 R14: ffffc900035c7ae0 R15: 0000000000000246
 rcu_lock_acquire+0x2a/0x30 include/linux/rcupdate.h:312
 rcu_read_lock include/linux/rcupdate.h:739 [inline]
 batadv_nc_purge_orig_hash net/batman-adv/network-coding.c:412 [inline]
 batadv_nc_worker+0xc1/0x5b0 net/batman-adv/network-coding.c:723
 process_one_work+0x8a1/0x10c0 kernel/workqueue.c:2310
 worker_thread+0xaca/0x1280 kernel/workqueue.c:2457
 kthread+0x3f6/0x4f0 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>
rcu: rcu_preempt kthread starved for 9875 jiffies! g67473 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:27064 pid:   15 ppid:     2 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5027 [inline]
 __schedule+0x12c4/0x45b0 kernel/sched/core.c:6373
 schedule+0x11b/0x1f0 kernel/sched/core.c:6456
 schedule_timeout+0x1b9/0x300 kernel/time/timer.c:1914
 rcu_gp_fqs_loop+0x2bf/0x1080 kernel/rcu/tree.c:1972
 rcu_gp_kthread+0xa4/0x360 kernel/rcu/tree.c:2145
 kthread+0x3f6/0x4f0 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1 skipped: idling at native_safe_halt arch/x86/include/asm/irqflags.h:51 [inline]
NMI backtrace for cpu 1 skipped: idling at arch_safe_halt arch/x86/include/asm/irqflags.h:89 [inline]
NMI backtrace for cpu 1 skipped: idling at acpi_safe_halt drivers/acpi/processor_idle.c:108 [inline]
NMI backtrace for cpu 1 skipped: idling at acpi_idle_do_entry+0x10f/0x340 drivers/acpi/processor_idle.c:562

Crashes (3):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2024/08/23 17:48 linux-5.15.y fa93fa65db6e d7d32352 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in kcov_mmap
2024/07/10 05:51 linux-5.15.y f45bea23c39c bc144f9a .config console log report info ci2-linux-5-15-kasan INFO: rcu detected stall in kcov_mmap
2024/05/24 02:35 linux-5.15.y 83655231580b 8f98448e .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in kcov_mmap
* Struck through repros no longer work on HEAD.