syzbot

 sign-in | mailing list | source | docs
🐞 Open [96]
🐞 Fixed [6]
🐞 Invalid [2]
≡ Crashes
Kernel Health Bugs/Month Bug Lifetimes Fuzzing
Total Repo Heatmap
💬 Send us feedback

INFO: task hung in synchronize_rcu

Status: internal: reported on 2025/07/11 21:20
Reported-by: syzbot+0232e02d8636b4ed7022@syzkaller.appspotmail.com
First crash: 68d, last: 1d22h
▶ ▼ Similar bugs (13)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: task hung in synchronize_rcu (3) 1 C done done 374 928d 1865d 22/29 fixed on 2023/02/24 13:50
linux-6.1 INFO: task hung in synchronize_rcu origin:lts-only 1 C unreliable 20 2d06h 883d 0/3 upstream: reported C repro on 2023/04/01 04:49
android-49 INFO: task hung in synchronize_rcu 1 1 2101d 2101d 0/3 auto-closed as invalid on 2020/03/28 16:57
linux-4.14 INFO: task hung in synchronize_rcu vfs 1 C error 162 942d 2124d 0/1 upstream: reported C repro on 2019/11/07 04:32
linux-4.19 INFO: task hung in synchronize_rcu 1 C error 70 932d 2122d 0/1 upstream: reported C repro on 2019/11/08 21:27
linux-5.15 INFO: task hung in synchronize_rcu 1 1 868d 868d 0/3 auto-obsoleted due to no activity on 2023/08/14 02:05
linux-5.15 INFO: task hung in synchronize_rcu (3) origin:lts-only 1 C error 14 27d 401d 0/3 upstream: reported C repro on 2024/07/26 03:55
upstream INFO: task hung in synchronize_rcu 1 syz done 1206 2102d 2128d 14/29 fixed on 2019/11/29 15:48
upstream INFO: task hung in synchronize_rcu (4) fs net 1 C done error 904 1d11h 850d 0/29 upstream: reported C repro on 2023/05/04 02:01
linux-5.15 INFO: task hung in synchronize_rcu (2) 1 1 556d 556d 0/3 auto-obsoleted due to no activity on 2024/05/31 13:53
android-414 INFO: task hung in synchronize_rcu 1 1 2120d 2120d 0/1 auto-closed as invalid on 2020/03/10 10:42
upstream INFO: task hung in synchronize_rcu (2) trace 1 8 2100d 2101d 0/29 closed as invalid on 2019/11/30 16:54
upstream INFO: task hung in rtnetlink_rcv_msg net 1 C inconclusive inconclusive 1970 418d 2381d 26/29 fixed on 2024/07/09 19:14

Sample crash report:
INFO: task kworker/0:1:10 blocked for more than 123 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/0:1     state:D stack:0     pid:10    tgid:10    ppid:2      flags:0x00004000
Workqueue: events xfrm_state_gc_task
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5945 [inline]
 __schedule+0x1322/0x1df0 kernel/sched/core.c:7791
 __schedule_loop kernel/sched/core.c:7872 [inline]
 schedule+0xc6/0x240 kernel/sched/core.c:7887
 exp_funnel_lock kernel/rcu/tree_exp.h:320 [inline]
 synchronize_rcu_expedited+0x4ee/0x7b0 kernel/rcu/tree_exp.h:976
 synchronize_rcu+0x77/0x2e0 kernel/rcu/tree.c:4119
 xfrm_state_gc_task+0xca/0x170 net/xfrm/xfrm_state.c:569
 process_one_work kernel/workqueue.c:3238 [inline]
 process_scheduled_works+0x7d5/0x1020 kernel/workqueue.c:3319
 worker_thread+0xc58/0x1250 kernel/workqueue.c:3400
 kthread+0x2c7/0x370 kernel/kthread.c:389
 ret_from_fork+0x67/0xa0 arch/x86/kernel/process.c:153
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>
INFO: task kworker/u8:2:46 blocked for more than 125 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u8:2    state:D stack:0     pid:46    tgid:46    ppid:2      flags:0x00004000
Workqueue: ipv6_addrconf addrconf_verify_work
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5945 [inline]
 __schedule+0x1322/0x1df0 kernel/sched/core.c:7791
 __schedule_loop kernel/sched/core.c:7872 [inline]
 schedule+0xc6/0x240 kernel/sched/core.c:7887
 schedule_preempt_disabled+0x14/0x30 kernel/sched/core.c:7944
 __mutex_lock_common kernel/locking/mutex.c:707 [inline]
 __mutex_lock+0x81e/0x1b50 kernel/locking/mutex.c:803
 __mutex_lock_slowpath+0xe/0x20 kernel/locking/mutex.c:1134
 mutex_lock+0x102/0x1c0 kernel/locking/mutex.c:285
 rtnl_lock+0x19/0x20 net/core/rtnetlink.c:79
 addrconf_verify_work+0x1d/0x50 net/ipv6/addrconf.c:4780
 process_one_work kernel/workqueue.c:3238 [inline]
 process_scheduled_works+0x7d5/0x1020 kernel/workqueue.c:3319
 worker_thread+0xc58/0x1250 kernel/workqueue.c:3400
 kthread+0x2c7/0x370 kernel/kthread.c:389
 ret_from_fork+0x67/0xa0 arch/x86/kernel/process.c:153
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>
INFO: task syz.1.2339:7376 blocked for more than 126 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.1.2339      state:D stack:0     pid:7376  tgid:7376  ppid:7235   flags:0x00004006
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5945 [inline]
 __schedule+0x1322/0x1df0 kernel/sched/core.c:7791
 __schedule_loop kernel/sched/core.c:7872 [inline]
 schedule+0xc6/0x240 kernel/sched/core.c:7887
 schedule_preempt_disabled+0x14/0x30 kernel/sched/core.c:7944
 __mutex_lock_common kernel/locking/mutex.c:707 [inline]
 __mutex_lock+0x81e/0x1b50 kernel/locking/mutex.c:803
 __mutex_lock_slowpath+0xe/0x20 kernel/locking/mutex.c:1134
 mutex_lock+0x102/0x1c0 kernel/locking/mutex.c:285
 exp_funnel_lock kernel/rcu/tree_exp.h:329 [inline]
 synchronize_rcu_expedited+0x288/0x7b0 kernel/rcu/tree_exp.h:976
 synchronize_net+0x2c/0x40 net/core/dev.c:11368
 dev_deactivate_many+0x6dd/0xbe0 net/sched/sch_generic.c:1377
 __dev_close_many+0x211/0x370 net/core/dev.c:1618
 dev_close_many+0x225/0x4f0 net/core/dev.c:1656
 unregister_netdevice_many_notify+0x4bb/0x1bd0 net/core/dev.c:11463
 unregister_netdevice_many net/core/dev.c:11551 [inline]
 unregister_netdevice_queue+0x339/0x380 net/core/dev.c:11425
 unregister_netdevice include/linux/netdevice.h:3165 [inline]
 ppp_release+0xf0/0x200 drivers/net/ppp/ppp_generic.c:421
 __fput+0x1fb/0xa00 fs/file_table.c:429
 ____fput+0x20/0x30 fs/file_table.c:457
 task_work_run+0x1e3/0x250 kernel/task_work.c:240
 exit_task_work include/linux/task_work.h:43 [inline]
 do_exit+0x9bc/0x2630 kernel/exit.c:953
 do_group_exit+0x22a/0x300 kernel/exit.c:1095
 get_signal+0x139d/0x14f0 kernel/signal.c:2933
 arch_do_signal_or_restart+0x96/0x720 arch/x86/kernel/signal.c:337
 exit_to_user_mode_loop kernel/entry/common.c:111 [inline]
 exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
 syscall_exit_to_user_mode+0x58/0xb0 kernel/entry/common.c:218
 do_syscall_64+0x64/0xf0 arch/x86/entry/common.c:89
 entry_SYSCALL_64_after_hwframe+0x76/0x7e
RIP: 0033:0x7f525b9c14a5
RSP: 002b:00007f525c835f80 EFLAGS: 00000293 ORIG_RAX: 00000000000000e6
RAX: fffffffffffffdfc RBX: 00007f525bbb5fa0 RCX: 00007f525b9c14a5
RDX: 00007f525c835fc0 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007f525ba11e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000000
R13: 00007f525bbb6038 R14: 00007f525bbb5fa0 R15: 00007ffe33f4a538
 </TASK>
INFO: task syz.1.2379:7491 blocked for more than 128 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.1.2379      state:D stack:0     pid:7491  tgid:7491  ppid:7235   flags:0x00004006
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5945 [inline]
 __schedule+0x1322/0x1df0 kernel/sched/core.c:7791
 __schedule_loop kernel/sched/core.c:7872 [inline]
 schedule+0xc6/0x240 kernel/sched/core.c:7887
 synchronize_rcu_expedited+0x6b0/0x7b0 kernel/rcu/tree_exp.h:991
 synchronize_rcu+0x77/0x2e0 kernel/rcu/tree.c:4119
 synchronize_net+0x38/0x40 net/core/dev.c:11370
 packet_release+0x9f8/0xd50 net/packet/af_packet.c:3217
 __sock_release net/socket.c:659 [inline]
 sock_close+0xda/0x280 net/socket.c:1427
 __fput+0x1fb/0xa00 fs/file_table.c:429
 ____fput+0x20/0x30 fs/file_table.c:457
 task_work_run+0x1e3/0x250 kernel/task_work.c:240
 exit_task_work include/linux/task_work.h:43 [inline]
 do_exit+0x9bc/0x2630 kernel/exit.c:953
 do_group_exit+0x22a/0x300 kernel/exit.c:1095
 get_signal+0x139d/0x14f0 kernel/signal.c:2933
 arch_do_signal_or_restart+0x96/0x720 arch/x86/kernel/signal.c:337
 exit_to_user_mode_loop kernel/entry/common.c:111 [inline]
 exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
 syscall_exit_to_user_mode+0x58/0xb0 kernel/entry/common.c:218
 do_syscall_64+0x64/0xf0 arch/x86/entry/common.c:89
 entry_SYSCALL_64_after_hwframe+0x76/0x7e
RIP: 0033:0x7f525b9c14a5
RSP: 002b:00007f525c835f80 EFLAGS: 00000293 ORIG_RAX: 00000000000000e6
RAX: fffffffffffffdfc RBX: 00007f525bbb5fa0 RCX: 00007f525b9c14a5
RDX: 00007f525c835fc0 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007f525ba11e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000000
R13: 00007f525bbb6038 R14: 00007f525bbb5fa0 R15: 00007ffe33f4a538
 </TASK>
INFO: task syz.0.2427:7624 blocked for more than 129 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.2427      state:D stack:0     pid:7624  tgid:7624  ppid:6520   flags:0x00004006
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5945 [inline]
 __schedule+0x1322/0x1df0 kernel/sched/core.c:7791
 __schedule_loop kernel/sched/core.c:7872 [inline]
 schedule+0xc6/0x240 kernel/sched/core.c:7887
 exp_funnel_lock kernel/rcu/tree_exp.h:320 [inline]
 synchronize_rcu_expedited+0x4ee/0x7b0 kernel/rcu/tree_exp.h:976
 synchronize_rcu+0x77/0x2e0 kernel/rcu/tree.c:4119
 pptp_release+0x147/0x310 drivers/net/ppp/pptp.c:517
 __sock_release net/socket.c:659 [inline]
 sock_close+0xda/0x280 net/socket.c:1427
 __fput+0x1fb/0xa00 fs/file_table.c:429
 ____fput+0x20/0x30 fs/file_table.c:457
 task_work_run+0x1e3/0x250 kernel/task_work.c:240
 exit_task_work include/linux/task_work.h:43 [inline]
 do_exit+0x9bc/0x2630 kernel/exit.c:953
 do_group_exit+0x22a/0x300 kernel/exit.c:1095
 get_signal+0x139d/0x14f0 kernel/signal.c:2933
 arch_do_signal_or_restart+0x96/0x720 arch/x86/kernel/signal.c:337
 exit_to_user_mode_loop kernel/entry/common.c:111 [inline]
 exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
 syscall_exit_to_user_mode+0x58/0xb0 kernel/entry/common.c:218
 do_syscall_64+0x64/0xf0 arch/x86/entry/common.c:89
 entry_SYSCALL_64_after_hwframe+0x76/0x7e
RIP: 07ff:0x0
RSP: 642f:0000000000000000 EFLAGS: 00000202 ORIG_RAX: 0000000000000000
RAX: 0000000000000000 RBX: 0000000000000001 RCX: 000000006e616c76
RDX: 0000000000000031 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: cf9d780a350b4549 R09: c7e58b697db8ef3d
R10: d68d02d45a22dc24 R11: 19b4d49ef33da9ed R12: 39cb75b6fa6cb3d1
R13: a8d7b5dbf29d588f R14: 9b8908dcbb4f02b4 R15: 107b9d1451766018
 </TASK>
INFO: task syz.1.2474:7745 blocked for more than 130 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.1.2474      state:D stack:0     pid:7745  tgid:7745  ppid:7235   flags:0x00004006
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5945 [inline]
 __schedule+0x1322/0x1df0 kernel/sched/core.c:7791
 __schedule_loop kernel/sched/core.c:7872 [inline]
 schedule+0xc6/0x240 kernel/sched/core.c:7887
 exp_funnel_lock kernel/rcu/tree_exp.h:320 [inline]
 synchronize_rcu_expedited+0x4ee/0x7b0 kernel/rcu/tree_exp.h:976
 namespace_unlock+0x1ec/0x3d0 fs/namespace.c:1700
 drop_collected_mounts fs/namespace.c:2228 [inline]
 put_mnt_ns+0xad/0xf0 fs/namespace.c:5585
 free_nsproxy+0x52/0x290 kernel/nsproxy.c:193
 put_nsproxy include/linux/nsproxy.h:118 [inline]
 switch_task_namespaces kernel/nsproxy.c:251 [inline]
 exit_task_namespaces+0x99/0xe0 kernel/nsproxy.c:256
 do_exit+0x9b7/0x2630 kernel/exit.c:952
 do_group_exit+0x22a/0x300 kernel/exit.c:1095
 get_signal+0x139d/0x14f0 kernel/signal.c:2933
 arch_do_signal_or_restart+0x96/0x720 arch/x86/kernel/signal.c:337
 exit_to_user_mode_loop kernel/entry/common.c:111 [inline]
 exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
 syscall_exit_to_user_mode+0x58/0xb0 kernel/entry/common.c:218
 do_syscall_64+0x64/0xf0 arch/x86/entry/common.c:89
 entry_SYSCALL_64_after_hwframe+0x76/0x7e
RIP: 0033:0x7f525b9c14a5
RSP: 002b:00007f525c835f80 EFLAGS: 00000293 ORIG_RAX: 00000000000000e6
RAX: fffffffffffffdfc RBX: 00007f525bbb5fa0 RCX: 00007f525b9c14a5
RDX: 00007f525c835fc0 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007f525ba11e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000000
R13: 00007f525bbb6038 R14: 00007f525bbb5fa0 R15: 00007ffe33f4a538
 </TASK>
INFO: task syz.4.2835:8783 blocked for more than 132 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.4.2835      state:D stack:0     pid:8783  tgid:8783  ppid:8684   flags:0x00004006
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5945 [inline]
 __schedule+0x1322/0x1df0 kernel/sched/core.c:7791
 __schedule_loop kernel/sched/core.c:7872 [inline]
 schedule+0xc6/0x240 kernel/sched/core.c:7887
 exp_funnel_lock kernel/rcu/tree_exp.h:320 [inline]
 synchronize_rcu_expedited+0x4ee/0x7b0 kernel/rcu/tree_exp.h:976
 synchronize_rcu+0x77/0x2e0 kernel/rcu/tree.c:4119
 bcm_release+0x638/0x8d0 net/can/bcm.c:1642
 __sock_release net/socket.c:659 [inline]
 sock_close+0xda/0x280 net/socket.c:1427

Crashes (25):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/08/29 14:23 android16-6.12 cbb0a15dcc1e 3e1beec6 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust INFO: task hung in synchronize_rcu
2025/08/28 20:00 android16-6.12 cbb0a15dcc1e d401b9d7 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust INFO: task hung in synchronize_rcu
2025/08/28 02:44 android16-6.12 c17d1926681a e12e5ba4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust INFO: task hung in synchronize_rcu
2025/08/10 15:52 android16-6.12 d0c633175c04 32a0e5ed .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust INFO: task hung in synchronize_rcu
2025/08/08 08:40 android16-6.12 209015b548fb 6a893178 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust INFO: task hung in synchronize_rcu
2025/08/06 04:02 android16-6.12 78c6c49396da ffe1dd46 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust INFO: task hung in synchronize_rcu
2025/08/02 02:42 android16-6.12 bf0fb8bb181b 7368264b .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust INFO: task hung in synchronize_rcu
2025/08/01 23:52 android16-6.12 bf0fb8bb181b 7368264b .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust INFO: task hung in synchronize_rcu
2025/07/27 13:59 android16-6.12 e9bbc29c066a fb8f743d .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust INFO: task hung in synchronize_rcu
2025/07/23 16:19 android16-6.12 fc2476d0896a e1dd4f22 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust INFO: task hung in synchronize_rcu
2025/07/22 07:02 android16-6.12 2199f5c4b596 1555463b .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust INFO: task hung in synchronize_rcu
2025/07/22 06:27 android16-6.12 2199f5c4b596 1555463b .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust INFO: task hung in synchronize_rcu
2025/07/22 00:07 android16-6.12 25f19cb85021 56d87229 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust INFO: task hung in synchronize_rcu
2025/07/15 19:24 android16-6.12 603af016e4a8 03fcfc4b .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust INFO: task hung in synchronize_rcu
2025/07/12 20:23 android16-6.12 21ed84930c16 3cda49cf .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust INFO: task hung in synchronize_rcu
2025/07/12 13:03 android16-6.12 21ed84930c16 3cda49cf .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust INFO: task hung in synchronize_rcu
2025/07/11 00:05 android16-6.12 8ea40f524391 3cda49cf .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust INFO: task hung in synchronize_rcu
2025/07/10 10:32 android16-6.12 d893caf112c8 956bd956 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust INFO: task hung in synchronize_rcu
2025/07/08 17:41 android16-6.12 15d2fe054444 4d9fdfa4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust INFO: task hung in synchronize_rcu
2025/07/08 10:31 android16-6.12 f6ca783ba264 4f67c4ae .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust INFO: task hung in synchronize_rcu
2025/07/07 00:11 android16-6.12 e2bf362ee23b 4f67c4ae .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust INFO: task hung in synchronize_rcu
2025/07/04 17:24 android16-6.12 e2bf362ee23b d869b261 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust INFO: task hung in synchronize_rcu
2025/07/03 23:49 android16-6.12 e2bf362ee23b 76ad128c .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust INFO: task hung in synchronize_rcu
2025/07/02 06:25 android16-6.12 c40c54e66959 bc80e4f0 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust INFO: task hung in synchronize_rcu
2025/06/24 05:10 android16-6.12 1d4f4d446dbd e2f27c35 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust INFO: task hung in synchronize_rcu
* Struck through repros no longer work on HEAD.