syzbot


INFO: task hung in iterate_supers

Status: upstream: reported C repro on 2025/06/20 00:37
Reported-by: syzbot+739c128b5557abb9f816@syzkaller.appspotmail.com
First crash: 90d, last: 3d23h
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 518 1h17m 89d 0/1 premoderation: reported C repro on 2025/06/21 16:44
android-414 INFO: task hung in iterate_supers 1 1 2515d 2353d 0/1 auto-closed as invalid on 2019/04/28 09:45
linux-4.14 INFO: task hung in iterate_supers 1 16 1723d 2338d 0/1 auto-closed as invalid on 2021/04/29 12:11
linux-4.19 INFO: task hung in iterate_supers (2) 1 1 1925d 1925d 0/1 auto-closed as invalid on 2020/10/09 12:15
upstream INFO: task hung in iterate_supers 9p 1 C error 5804 5d20h 2627d 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 331 1d08h 924d 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 310 3d05h 922d 0/3 upstream: reported C repro on 2023/03/10 21:24
linux-4.14 INFO: task hung in iterate_supers (2) 1 1 937d 937d 0/1 upstream: reported on 2023/02/24 15:59
linux-4.19 INFO: task hung in iterate_supers 1 7 2057d 2245d 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 926d 1733d 0/1 upstream: reported syz repro on 2020/12/20 03:38
android-49 INFO: task hung in iterate_supers 1 19 2577d 2677d 0/3 auto-closed as invalid on 2019/02/25 14:49
android-414 INFO: task hung in iterate_supers (2) 1 1 2334d 2334d 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 1557d 1553d 0/29 auto-closed as invalid on 2021/08/13 03:51

Sample crash report:
INFO: task syz.0.17:5967 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.17        state:D stack:28400 pid:5967  ppid:5914   flags:0x00004004
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
 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
 ksys_sync+0x95/0x150 fs/sync.c:102
 __ia32_sys_sync+0xe/0x20 fs/sync.c:113
 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: 0033:0x7f62fdf8ebe9
RSP: 002b:00007f62fee24038 EFLAGS: 00000246 ORIG_RAX: 00000000000000a2
RAX: ffffffffffffffda RBX: 00007f62fe1c6090 RCX: 00007f62fdf8ebe9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007f62fe1c6090 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f62fe1c6128 R14: 00007f62fe1c6090 R15: 00007ffde38a4368
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/29:
 #0: ffffffff8cd2fc20 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:334 [inline]
 #0: ffffffff8cd2fc20 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:786 [inline]
 #0: ffffffff8cd2fc20 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x55/0x290 kernel/locking/lockdep.c:6633
2 locks held by getty/5548:
 #0: ffff88814c20c0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc9000326e2f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x425/0x1380 drivers/tty/n_tty.c:2217
1 lock held by syz.0.17/5966:
 #0: ffff88807ab7a0e0 (&type->s_umount_key#55/1){+.+.}-{3:3}, at: alloc_super+0x1fa/0x920 fs/super.c:352
1 lock held by syz.0.17/5967:
 #0: ffff88807ab7a0e0 (&type->s_umount_key#74){.+.+}-{3:3}, at: __super_lock fs/super.c:58 [inline]
 #0: ffff88807ab7a0e0 (&type->s_umount_key#74){.+.+}-{3:3}, at: super_lock+0x167/0x360 fs/super.c:117
1 lock held by syz.1.18/5989:
 #0: ffff8880710da0e0 (&type->s_umount_key#55/1){+.+.}-{3:3}, at: alloc_super+0x1fa/0x920 fs/super.c:352
1 lock held by syz.1.18/5991:
 #0: ffff88807ab7a0e0 (&type->s_umount_key#74){.+.+}-{3:3}, at: __super_lock fs/super.c:58 [inline]
 #0: ffff88807ab7a0e0 (&type->s_umount_key#74){.+.+}-{3:3}, at: super_lock+0x167/0x360 fs/super.c:117
1 lock held by syz.2.19/6019:
 #0: ffff8880799c00e0 (&type->s_umount_key#55/1){+.+.}-{3:3}, at: alloc_super+0x1fa/0x920 fs/super.c:352
1 lock held by syz.2.19/6020:
 #0: ffff88807ab7a0e0 (&type->s_umount_key#74){.+.+}-{3:3}, at: __super_lock fs/super.c:58 [inline]
 #0: ffff88807ab7a0e0 (&type->s_umount_key#74){.+.+}-{3:3}, at: super_lock+0x167/0x360 fs/super.c:117
1 lock held by syz.3.20/6042:
 #0: ffff88802dda00e0 (&type->s_umount_key#55/1){+.+.}-{3:3}, at: alloc_super+0x1fa/0x920 fs/super.c:352
1 lock held by syz.3.20/6043:
 #0: ffff88807ab7a0e0 (&type->s_umount_key#74){.+.+}-{3:3}, at: __super_lock fs/super.c:58 [inline]
 #0: ffff88807ab7a0e0 (&type->s_umount_key#74){.+.+}-{3:3}, at: super_lock+0x167/0x360 fs/super.c:117
1 lock held by syz.4.21/6072:
 #0: ffff88807814a0e0 (&type->s_umount_key#55/1){+.+.}-{3:3}, at: alloc_super+0x1fa/0x920 fs/super.c:352
1 lock held by syz.4.21/6073:
 #0: ffff88807ab7a0e0 (&type->s_umount_key#74){.+.+}-{3:3}, at: __super_lock fs/super.c:58 [inline]
 #0: ffff88807ab7a0e0 (&type->s_umount_key#74){.+.+}-{3:3}, at: super_lock+0x167/0x360 fs/super.c:117
1 lock held by syz.5.22/6101:
 #0: ffff88805ce800e0 (&type->s_umount_key#55/1){+.+.}-{3:3}, at: alloc_super+0x1fa/0x920 fs/super.c:352
1 lock held by syz.5.22/6103:
 #0: ffff88807ab7a0e0 (&type->s_umount_key#74){.+.+}-{3:3}, at: __super_lock fs/super.c:58 [inline]
 #0: ffff88807ab7a0e0 (&type->s_umount_key#74){.+.+}-{3:3}, at: super_lock+0x167/0x360 fs/super.c:117
1 lock held by syz.6.23/6139:
 #0: ffff88805a7120e0 (&type->s_umount_key#55/1){+.+.}-{3:3}, at: alloc_super+0x1fa/0x920 fs/super.c:352
1 lock held by syz.6.23/6140:
 #0: ffff88807ab7a0e0 (&type->s_umount_key#74){.+.+}-{3:3}, at: __super_lock fs/super.c:58 [inline]
 #0: ffff88807ab7a0e0 (&type->s_umount_key#74){.+.+}-{3:3}, at: super_lock+0x167/0x360 fs/super.c:117
1 lock held by syz.7.24/6168:
 #0: ffff88805b7100e0 (&type->s_umount_key#55/1){+.+.}-{3:3}, at: alloc_super+0x1fa/0x920 fs/super.c:352
1 lock held by syz.7.24/6170:
 #0: ffff88807ab7a0e0 (&type->s_umount_key#74){.+.+}-{3:3}, at: __super_lock fs/super.c:58 [inline]
 #0: ffff88807ab7a0e0 (&type->s_umount_key#74){.+.+}-{3:3}, at: super_lock+0x167/0x360 fs/super.c:117
1 lock held by syz.8.25/6199:
 #0: ffff88805f56c0e0 (&type->s_umount_key#55/1){+.+.}-{3:3}, at: alloc_super+0x1fa/0x920 fs/super.c:352
1 lock held by syz.8.25/6200:
 #0: ffff88807ab7a0e0 (&type->s_umount_key#74){.+.+}-{3:3}, at: __super_lock fs/super.c:58 [inline]
 #0: ffff88807ab7a0e0 (&type->s_umount_key#74){.+.+}-{3:3}, at: super_lock+0x167/0x360 fs/super.c:117

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

NMI backtrace for cpu 1
CPU: 1 PID: 29 Comm: khungtaskd Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/14/2025
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 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 1081 Comm: kworker/u4:6 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/14/2025
Workqueue: bat_events batadv_nc_worker
RIP: 0010:separate_irq_context kernel/locking/lockdep.c:-1 [inline]
RIP: 0010:__lock_acquire+0xe6a/0x7c80 kernel/locking/lockdep.c:5121
Code: 00 49 b8 00 00 00 00 00 fc ff df 4d 89 3e 48 8b 44 24 78 42 0f b6 04 00 84 c0 0f 85 60 5c 00 00 48 8b 44 24 40 8b 18 48 85 db <4c> 8b b4 24 a8 00 00 00 74 5a 83 fb 31 0f 83 50 5d 00 00 48 8d 04
RSP: 0018:ffffc9000474f7c0 EFLAGS: 00000002
RAX: ffff88802337c6d8 RBX: 0000000000000002 RCX: ffffffff81671330
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff90da5500
RBP: ffffc9000474fa08 R08: dffffc0000000000 R09: 1ffffffff21b4aa0
R10: dffffc0000000000 R11: fffffbfff21b4aa1 R12: 0000000000000000
R13: ffff88802337bc00 R14: ffff88802337c730 R15: d7c71210ce46acba
FS:  0000000000000000(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffd42a2e000 CR3: 000000003027e000 CR4: 00000000003506f0
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 (13):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/09/09 17:22 linux-6.6.y 355bd0b51d2f d291dd2d .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: task hung in iterate_supers
2025/09/14 17:36 linux-6.6.y 60a9e718726f e2beed91 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: task hung in iterate_supers
2025/09/07 11:55 linux-6.6.y 355bd0b51d2f d291dd2d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: task hung in iterate_supers
2025/08/31 10:57 linux-6.6.y cc1a1c5b404a 807a3b61 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: task hung in iterate_supers
2025/08/29 08:31 linux-6.6.y cc1a1c5b404a d401b9d7 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: task hung in iterate_supers
2025/08/29 08:26 linux-6.6.y cc1a1c5b404a d401b9d7 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: task hung in iterate_supers
2025/08/24 20:47 linux-6.6.y bb9c90ab9c5a bf27483f .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: task hung in iterate_supers
2025/08/11 23:11 linux-6.6.y 3a8ababb8b6a c06e8995 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: task hung in iterate_supers
2025/08/10 02:06 linux-6.6.y 3a8ababb8b6a 32a0e5ed .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: task hung in iterate_supers
2025/07/28 13:31 linux-6.6.y dbcb8d8e4163 fb8f743d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: task hung in iterate_supers
2025/07/12 09:46 linux-6.6.y 59a2de10b81a 3cda49cf .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: task hung in iterate_supers
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.