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INFO: task hung in synchronize_rcu

Status: upstream: reported on 2025/10/30 17:16
Reported-by: syzbot+6d7cbd2cd15cb48338f3@syzkaller.appspotmail.com
First crash: 11d, last: 11d
▶ ▼ Similar bugs (14)
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 1000d 1937d 22/29 fixed on 2023/02/24 13:50
linux-6.1 INFO: task hung in synchronize_rcu origin:lts-only 1 C unreliable 25 8d20h 955d 0/3 upstream: reported C repro on 2023/04/01 04:49
android-49 INFO: task hung in synchronize_rcu 1 1 2173d 2173d 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 1014d 2196d 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 1004d 2194d 0/1 upstream: reported C repro on 2019/11/08 21:27
linux-5.15 INFO: task hung in synchronize_rcu 1 1 940d 940d 0/3 auto-obsoleted due to no activity on 2023/08/14 02:05
android-6-12 INFO: task hung in synchronize_rcu 1 40 2d08h 122d 0/1 internal: reported on 2025/07/11 21:20
linux-5.15 INFO: task hung in synchronize_rcu (3) origin:lts-only 1 C error 15 2d06h 473d 0/3 upstream: reported C repro on 2024/07/26 03:55
upstream INFO: task hung in synchronize_rcu 1 syz done 1206 2174d 2200d 14/29 fixed on 2019/11/29 15:48
upstream INFO: task hung in synchronize_rcu (4) fs net 1 C done error 1537 2d01h 922d 0/29 upstream: reported C repro on 2023/05/04 02:01
linux-5.15 INFO: task hung in synchronize_rcu (2) 1 1 629d 629d 0/3 auto-obsoleted due to no activity on 2024/05/31 13:53
android-414 INFO: task hung in synchronize_rcu 1 1 2192d 2192d 0/1 auto-closed as invalid on 2020/03/10 10:42
upstream INFO: task hung in synchronize_rcu (2) trace 1 8 2173d 2173d 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 490d 2453d 26/29 fixed on 2024/07/09 19:14

Sample crash report:
INFO: task kworker/u4:5:32095 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u4:5    state:D stack:24456 pid:32095 ppid:2      flags:0x00004000
Workqueue: netns cleanup_net
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5380 [inline]
 __schedule+0x14d2/0x44d0 kernel/sched/core.c:6699
 schedule+0xbd/0x170 kernel/sched/core.c:6773
 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:6832
 __mutex_lock_common kernel/locking/mutex.c:679 [inline]
 __mutex_lock+0x6b7/0xcc0 kernel/locking/mutex.c:747
 exp_funnel_lock kernel/rcu/tree_exp.h:324 [inline]
 synchronize_rcu_expedited+0x360/0x830 kernel/rcu/tree_exp.h:1004

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/10/30 17:16 linux-6.6.y e5bbb12db2c7 2c50b6a9 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: task hung in synchronize_rcu
* Struck through repros no longer work on HEAD.