syzbot


INFO: task hung in iterate_supers

Status: upstream: reported on 2025/06/20 00:37
Reported-by: syzbot+739c128b5557abb9f816@syzkaller.appspotmail.com
First crash: 20d, last: 1d10h
Similar bugs (13)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
android-6-12 INFO: task hung in iterate_supers origin:upstream 1 C 105 1h47m 18d 0/1 premoderation: reported C repro on 2025/06/21 16:44
android-414 INFO: task hung in iterate_supers 1 1 2445d 2282d 0/1 auto-closed as invalid on 2019/04/28 09:45
linux-4.14 INFO: task hung in iterate_supers 1 16 1652d 2267d 0/1 auto-closed as invalid on 2021/04/29 12:11
linux-4.19 INFO: task hung in iterate_supers (2) 1 1 1854d 1854d 0/1 auto-closed as invalid on 2020/10/09 12:15
upstream INFO: task hung in iterate_supers 9p 1 C error 5804 12d 2557d 0/29 upstream: reported C repro on 2018/07/10 10:30
linux-5.15 INFO: task hung in iterate_supers origin:lts-only 1 C 311 1d13h 854d 0/3 upstream: reported C repro on 2023/03/08 18:22
linux-6.1 INFO: task hung in iterate_supers origin:upstream 1 C 301 5d04h 852d 0/3 upstream: reported C repro on 2023/03/10 21:24
linux-4.14 INFO: task hung in iterate_supers (2) 1 1 866d 866d 0/1 upstream: reported on 2023/02/24 15:59
linux-4.19 INFO: task hung in iterate_supers 1 7 1987d 2174d 0/1 auto-closed as invalid on 2020/05/29 21:42
linux-4.19 INFO: task hung in iterate_supers (3) vfs reiserfs ntfs 1 syz 378 856d 1663d 0/1 upstream: reported syz repro on 2020/12/20 03:38
android-49 INFO: task hung in iterate_supers 1 19 2506d 2607d 0/3 auto-closed as invalid on 2019/02/25 14:49
android-414 INFO: task hung in iterate_supers (2) 1 1 2263d 2263d 0/1 auto-closed as invalid on 2019/10/25 08:49
upstream INFO: task can't die in iterate_supers (2) ceph fs 1 1 1487d 1483d 0/29 auto-closed as invalid on 2021/08/13 03:51

Sample crash report:
INFO: task syz.8.4198:24567 blocked for more than 143 seconds.
      Not tainted 6.6.96-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.8.4198      state:D stack:25928 pid:24567 ppid:15018  flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5381 [inline]
 __schedule+0x14e2/0x4580 kernel/sched/core.c:6700
 schedule+0xbd/0x170 kernel/sched/core.c:6774
 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:6833
 rwsem_down_read_slowpath+0x4f8/0x840 kernel/locking/rwsem.c:1086
 __down_read_common kernel/locking/rwsem.c:1250 [inline]
 __down_read kernel/locking/rwsem.c:1263 [inline]
 down_read+0x98/0x2e0 kernel/locking/rwsem.c:1522
 __super_lock fs/super.c:58 [inline]
 super_lock+0x167/0x360 fs/super.c:117
 super_lock_shared fs/super.c:146 [inline]
 iterate_supers+0x80/0x170 fs/super.c:977
 quota_sync_all fs/quota/quota.c:69 [inline]
 __do_sys_quotactl fs/quota/quota.c:938 [inline]
 __se_sys_quotactl+0x355/0x950 fs/quota/quota.c:917
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f867d18e929
RSP: 002b:00007f867e02c038 EFLAGS: 00000246 ORIG_RAX: 00000000000000b3
RAX: ffffffffffffffda RBX: 00007f867d3b6240 RCX: 00007f867d18e929
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff80000100
RBP: 00007f867d210b39 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f867d3b6240 R15: 00007ffcb81af3e8
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/29:
 #0: ffffffff8cd2f760 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:334 [inline]
 #0: ffffffff8cd2f760 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:786 [inline]
 #0: ffffffff8cd2f760 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x55/0x290 kernel/locking/lockdep.c:6633
3 locks held by kworker/u4:10/3474:
2 locks held by getty/5557:
 #0: ffff88802d81e0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc9000327b2f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x425/0x1380 drivers/tty/n_tty.c:2217
2 locks held by kworker/0:7/16628:
 #0: ffff888017872538 ((wq_completion)rcu_gp){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline]
 #0: ffff888017872538 ((wq_completion)rcu_gp){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711
 #1: ffffc9000469fd00 ((work_completion)(&rew->rew_work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline]
 #1: ffffc9000469fd00 ((work_completion)(&rew->rew_work)){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711
4 locks held by kworker/u4:16/21927:
 #0: ffff888017873938 ((wq_completion)netns){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline]
 #0: ffff888017873938 ((wq_completion)netns){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711
 #1: ffffc9000f6cfd00 (net_cleanup_work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline]
 #1: ffffc9000f6cfd00 (net_cleanup_work){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711
 #2: ffffffff8dfae950 (pernet_ops_rwsem){++++}-{3:3}, at: cleanup_net+0x136/0xb90 net/core/net_namespace.c:606
 #3: ffffffff8cd35600 (rcu_state.barrier_mutex){+.+.}-{3:3}, at: rcu_barrier+0x4c/0x580 kernel/rcu/tree.c:4085
1 lock held by syz-executor/22716:
 #0: ffff88807b4740e0 (&type->s_umount_key#89){++++}-{3:3}, at: __super_lock fs/super.c:56 [inline]
 #0: ffff88807b4740e0 (&type->s_umount_key#89){++++}-{3:3}, at: __super_lock_excl fs/super.c:71 [inline]
 #0: ffff88807b4740e0 (&type->s_umount_key#89){++++}-{3:3}, at: deactivate_super+0xa4/0xe0 fs/super.c:513
1 lock held by syz.8.4198/24567:
 #0: ffff88807b4740e0 (&type->s_umount_key#89){++++}-{3:3}, at: __super_lock fs/super.c:58 [inline]
 #0: ffff88807b4740e0 (&type->s_umount_key#89){++++}-{3:3}, at: super_lock+0x167/0x360 fs/super.c:117
3 locks held by kworker/0:1/24693:
 #0: ffff888017870938 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline]
 #0: ffff888017870938 ((wq_completion)events){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711
 #1: ffffc9000c9e7d00 (free_ipc_work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline]
 #1: ffffc9000c9e7d00 (free_ipc_work){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711
 #2: ffffffff8cd35738 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:324 [inline]
 #2: ffffffff8cd35738 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x360/0x830 kernel/rcu/tree_exp.h:1004
1 lock held by syz.4.4301/25048:
 #0: ffff88807b4740e0 (&type->s_umount_key#89){++++}-{3:3}, at: __super_lock fs/super.c:58 [inline]
 #0: ffff88807b4740e0 (&type->s_umount_key#89){++++}-{3:3}, at: super_lock+0x167/0x360 fs/super.c:117
1 lock held by syz.9.4340/25221:
 #0: ffff88807b4740e0 (&type->s_umount_key#89){++++}-{3:3}, at: __super_lock fs/super.c:58 [inline]
 #0: ffff88807b4740e0 (&type->s_umount_key#89){++++}-{3:3}, at: super_lock+0x167/0x360 fs/super.c:117
3 locks held by syz-executor/25358:
 #0: ffff88802d2b4e30 (&hdev->req_lock){+.+.}-{3:3}, at: hci_dev_do_close net/bluetooth/hci_core.c:503 [inline]
 #0: ffff88802d2b4e30 (&hdev->req_lock){+.+.}-{3:3}, at: hci_unregister_dev+0x1fe/0x500 net/bluetooth/hci_core.c:2683
 #1: ffff88802d2b4078 (&hdev->lock){+.+.}-{3:3}, at: hci_dev_close_sync+0x4c9/0xfb0 net/bluetooth/hci_sync.c:5215
 #2: ffffffff8e128c28 (hci_cb_list_lock){+.+.}-{3:3}, at: hci_disconn_cfm include/net/bluetooth/hci_core.h:1980 [inline]
 #2: ffffffff8e128c28 (hci_cb_list_lock){+.+.}-{3:3}, at: hci_conn_hash_flush+0xa1/0x220 net/bluetooth/hci_conn.c:2539
1 lock held by syz-executor/25540:
 #0: ffffffff8cd35738 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:324 [inline]
 #0: ffffffff8cd35738 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x360/0x830 kernel/rcu/tree_exp.h:1004
4 locks held by syz.1.4425/25606:
 #0: ffff88806635ce30 (&hdev->req_lock){+.+.}-{3:3}, at: hci_dev_do_close net/bluetooth/hci_core.c:503 [inline]
 #0: ffff88806635ce30 (&hdev->req_lock){+.+.}-{3:3}, at: hci_unregister_dev+0x1fe/0x500 net/bluetooth/hci_core.c:2683
 #1: ffff88806635c078 (&hdev->lock){+.+.}-{3:3}, at: hci_dev_close_sync+0x4c9/0xfb0 net/bluetooth/hci_sync.c:5215
 #2: ffffffff8e128c28 (hci_cb_list_lock){+.+.}-{3:3}, at: hci_disconn_cfm include/net/bluetooth/hci_core.h:1980 [inline]
 #2: ffffffff8e128c28 (hci_cb_list_lock){+.+.}-{3:3}, at: hci_conn_hash_flush+0xa1/0x220 net/bluetooth/hci_conn.c:2539
 #3: ffff88807a156338 (&conn->lock#2){+.+.}-{3:3}, at: l2cap_conn_del+0x70/0x660 net/bluetooth/l2cap_core.c:1762
2 locks held by syz.3.4426/25603:
 #0: ffff8880315a8e30 (&hdev->req_lock){+.+.}-{3:3}, at: hci_dev_do_close net/bluetooth/hci_core.c:503 [inline]
 #0: ffff8880315a8e30 (&hdev->req_lock){+.+.}-{3:3}, at: hci_unregister_dev+0x1fe/0x500 net/bluetooth/hci_core.c:2683
 #1: ffff8880315a8078 (&hdev->lock){+.+.}-{3:3}, at: hci_dev_close_sync+0x4c9/0xfb0 net/bluetooth/hci_sync.c:5215

=============================================

NMI backtrace for cpu 0
CPU: 0 PID: 29 Comm: khungtaskd Not tainted 6.6.96-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x16c/0x230 lib/dump_stack.c:106
 nmi_cpu_backtrace+0x39b/0x3d0 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x17a/0x2f0 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:160 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:222 [inline]
 watchdog+0xf41/0xf80 kernel/hung_task.c:379
 kthread+0x2fa/0x390 kernel/kthread.c:388
 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
 </TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 21948 Comm: kworker/u4:36 Not tainted 6.6.96-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Workqueue: bat_events batadv_nc_worker
RIP: 0010:separate_irq_context kernel/locking/lockdep.c:4628 [inline]
RIP: 0010:__lock_acquire+0xe92/0x7c80 kernel/locking/lockdep.c:5121
Code: 85 db 4c 8b b4 24 a8 00 00 00 74 5a 83 fb 31 0f 83 50 5d 00 00 48 8d 04 9b 49 8d 5c c6 f8 48 89 d8 48 c1 e8 03 42 0f b6 04 00 <84> c0 0f 85 51 5d 00 00 8b 1b 48 8b 44 24 48 42 0f b6 04 00 84 c0
RSP: 0018:ffffc9000f7cf7c0 EFLAGS: 00000806
RAX: 0000000000000000 RBX: ffff888031fe8b28 RCX: ffffffff81670ba0
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff90da5520
RBP: ffffc9000f7cfa08 R08: dffffc0000000000 R09: 1ffffffff21b4aa4
R10: dffffc0000000000 R11: fffffbfff21b4aa5 R12: 0000000000000000
R13: ffff888031fe8000 R14: ffff888031fe8ae0 R15: b98d254c0818c18a
FS:  0000000000000000(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000557353b92000 CR3: 000000000cb30000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000097 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 lock_acquire+0x197/0x410 kernel/locking/lockdep.c:5754
 rcu_lock_acquire include/linux/rcupdate.h:334 [inline]
 rcu_read_lock include/linux/rcupdate.h:786 [inline]
 batadv_nc_purge_orig_hash net/batman-adv/network-coding.c:408 [inline]
 batadv_nc_worker+0xef/0x610 net/batman-adv/network-coding.c:719
 process_one_work kernel/workqueue.c:2634 [inline]
 process_scheduled_works+0xa45/0x15b0 kernel/workqueue.c:2711
 worker_thread+0xa55/0xfc0 kernel/workqueue.c:2792
 kthread+0x2fa/0x390 kernel/kthread.c:388
 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
 </TASK>

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/07/09 01:03 linux-6.6.y a5df3a702b2c 4d9fdfa4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: task hung in iterate_supers
2025/06/20 00:37 linux-6.6.y 6282921b6825 ed3e87f7 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: task hung in iterate_supers
* Struck through repros no longer work on HEAD.