syzbot


INFO: task hung in hfs_mdb_commit

Status: upstream: reported on 2025/08/29 18:32
Reported-by: syzbot+2b0baaa2f2e7a4694e14@syzkaller.appspotmail.com
First crash: 3d00h, last: 3d00h
Similar bugs (9)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: task hung in hfs_mdb_commit hfs 1 C error done 25 581d 959d 25/29 fixed on 2024/03/20 11:33
linux-6.1 INFO: task hung in hfs_mdb_commit 1 1 832d 832d 0/3 auto-obsoleted due to no activity on 2023/08/31 05:50
linux-5.15 INFO: task hung in hfs_mdb_commit (2) origin:upstream 1 C error 8 4d19h 511d 0/3 upstream: reported C repro on 2024/04/08 12:18
linux-4.19 INFO: task hung in hfs_mdb_commit hfs 1 C error 1 950d 950d 0/1 upstream: reported C repro on 2023/01/25 02:58
linux-6.1 INFO: task hung in hfs_mdb_commit (3) 1 1 200d 200d 0/3 auto-obsoleted due to no activity on 2025/05/23 22:52
linux-5.15 INFO: task hung in hfs_mdb_commit 1 1 814d 814d 0/3 auto-obsoleted due to no activity on 2023/09/18 06:33
linux-6.1 INFO: task hung in hfs_mdb_commit (2) 1 1 512d 512d 0/3 auto-obsoleted due to no activity on 2024/07/16 10:21
upstream INFO: task hung in hfs_mdb_commit (2) hfs 1 1 433d 433d 0/29 auto-obsoleted due to no activity on 2024/09/23 18:09
upstream INFO: task hung in hfs_mdb_commit (3) hfs 1 C error done 10 1d04h 80d 0/29 upstream: reported C repro on 2025/06/13 11:04

Sample crash report:
INFO: task kworker/0:0:8 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/0:0     state:D stack:21648 pid:8     ppid:2      flags:0x00004000
Workqueue: events_long flush_mdb
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
 io_schedule+0x80/0xd0 kernel/sched/core.c:9022
 bit_wait_io+0x11/0xd0 kernel/sched/wait_bit.c:209
 __wait_on_bit_lock+0xdc/0x580 kernel/sched/wait_bit.c:90
 out_of_line_wait_on_bit_lock+0x123/0x170 kernel/sched/wait_bit.c:117
 lock_buffer include/linux/buffer_head.h:385 [inline]
 hfs_mdb_commit+0x115/0x1120 fs/hfs/mdb.c:271
 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>
INFO: task syz-executor:11693 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor    state:D stack:20776 pid:11693 ppid:1      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
 io_schedule+0x80/0xd0 kernel/sched/core.c:9022
 bit_wait_io+0x11/0xd0 kernel/sched/wait_bit.c:209
 __wait_on_bit_lock+0xdc/0x580 kernel/sched/wait_bit.c:90
 out_of_line_wait_on_bit_lock+0x123/0x170 kernel/sched/wait_bit.c:117
 lock_buffer include/linux/buffer_head.h:385 [inline]
 hfs_mdb_commit+0xc5f/0x1120 fs/hfs/mdb.c:325
 hfs_sync_fs+0x15/0x20 fs/hfs/super.c:35
 sync_filesystem+0xea/0x220 fs/sync.c:56
 generic_shutdown_super+0x6f/0x2b0 fs/super.c:666
 kill_block_super+0x44/0x90 fs/super.c:1660
 deactivate_locked_super+0x97/0x100 fs/super.c:481
 cleanup_mnt+0x429/0x4c0 fs/namespace.c:1250
 task_work_run+0x1ce/0x250 kernel/task_work.c:239
 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
 exit_to_user_mode_loop+0xe6/0x110 kernel/entry/common.c:177
 exit_to_user_mode_prepare+0xb1/0x140 kernel/entry/common.c:210
 __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline]
 syscall_exit_to_user_mode+0x1a/0x50 kernel/entry/common.c:302
 do_syscall_64+0x61/0xb0 arch/x86/entry/common.c:87
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f0cd178ff17
RSP: 002b:00007ffdd571d488 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 00007f0cd1811c05 RCX: 00007f0cd178ff17
RDX: 0000000000000000 RSI: 0000000000000009 RDI: 00007ffdd571d540
RBP: 00007ffdd571d540 R08: 0000000000000000 R09: 0000000000000000
R10: 00000000ffffffff R11: 0000000000000246 R12: 00007ffdd571e5d0
R13: 00007f0cd1811c05 R14: 00000000001e800e R15: 00007ffdd571e610
 </TASK>

Showing all locks held in the system:
2 locks held by kworker/0:0/8:
 #0: ffff888017871138 ((wq_completion)events_long){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline]
 #0: ffff888017871138 ((wq_completion)events_long){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711
 #1: ffffc900000d7d00 ((work_completion)(&(&sbi->mdb_work)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline]
 #1: ffffc900000d7d00 ((work_completion)(&(&sbi->mdb_work)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711
1 lock held by khungtaskd/29:
 #0: ffffffff8cd2fbe0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:334 [inline]
 #0: ffffffff8cd2fbe0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:786 [inline]
 #0: ffffffff8cd2fbe0 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x55/0x290 kernel/locking/lockdep.c:6633
2 locks held by getty/5542:
 #0: ffff8880314d20a0 (&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-executor/11693:
 #0: ffff8880782ce0e0 (&type->s_umount_key#53){+.+.}-{3:3}, at: __super_lock fs/super.c:56 [inline]
 #0: ffff8880782ce0e0 (&type->s_umount_key#53){+.+.}-{3:3}, at: __super_lock_excl fs/super.c:71 [inline]
 #0: ffff8880782ce0e0 (&type->s_umount_key#53){+.+.}-{3:3}, at: deactivate_super+0xa4/0xe0 fs/super.c:513
4 locks held by kworker/u4:1/19043:

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

NMI backtrace for cpu 0
CPU: 0 PID: 29 Comm: khungtaskd Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
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: 42 Comm: kworker/u4:2 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Workqueue: events_unbound cfg80211_wiphy_work
RIP: 0010:on_stack arch/x86/include/asm/stacktrace.h:58 [inline]
RIP: 0010:stack_access_ok arch/x86/kernel/unwind_orc.c:393 [inline]
RIP: 0010:deref_stack_reg arch/x86/kernel/unwind_orc.c:403 [inline]
RIP: 0010:unwind_next_frame+0xf02/0x2970 arch/x86/kernel/unwind_orc.c:585
Code: 10 48 b8 00 00 00 00 00 fc ff df 48 8b 4c 24 18 0f b6 04 01 84 c0 0f 85 a7 15 00 00 8b 6d 00 31 ff 89 ee e8 90 e1 4a 00 85 ed <0f> 95 c0 4c 39 f3 0f 96 c1 20 c1 4d 39 f7 0f 97 c0 84 c1 0f 84 fd
RSP: 0018:ffffc90000b2ed58 EFLAGS: 00000202
RAX: ffffffff813ab1c0 RBX: ffffc90000b28000 RCX: 0000000000000000
RDX: ffff8880182a1e00 RSI: 0000000000000001 RDI: 0000000000000000
RBP: 0000000000000001 R08: ffff8880182a1e00 R09: 0000000000000003
R10: 0000000000000004 R11: 0000000000000000 R12: 1ffff92000165dc6
R13: 1ffff92000165dc7 R14: ffffc90000b2f6d8 R15: ffffc90000b30000
FS:  0000000000000000(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00005586e8e85088 CR3: 000000000cb30000 CR4: 00000000003506e0
Call Trace:
 <TASK>
 arch_stack_walk+0x144/0x190 arch/x86/kernel/stacktrace.c:25
 stack_trace_save+0x9c/0xe0 kernel/stacktrace.c:122
 kasan_save_stack mm/kasan/common.c:45 [inline]
 kasan_set_track+0x4e/0x70 mm/kasan/common.c:52
 kasan_save_free_info+0x2e/0x50 mm/kasan/generic.c:522
 ____kasan_slab_free+0x126/0x1e0 mm/kasan/common.c:236
 kasan_slab_free include/linux/kasan.h:164 [inline]
 slab_free_hook mm/slub.c:1806 [inline]
 slab_free_freelist_hook+0x130/0x1b0 mm/slub.c:1832
 slab_free mm/slub.c:3816 [inline]
 __kmem_cache_free+0xba/0x1f0 mm/slub.c:3829
 ieee80211_inform_bss+0xba9/0x1060 net/mac80211/scan.c:160
 rdev_inform_bss+0x106/0x410 net/wireless/rdev-ops.h:418
 cfg80211_inform_single_bss_frame_data net/wireless/scan.c:2985 [inline]
 cfg80211_inform_bss_frame_data+0xb33/0x12b0 net/wireless/scan.c:3012
 ieee80211_bss_info_update+0x70b/0x930 net/mac80211/scan.c:211
 ieee80211_rx_bss_info net/mac80211/ibss.c:1124 [inline]
 ieee80211_rx_mgmt_probe_beacon net/mac80211/ibss.c:1613 [inline]
 ieee80211_ibss_rx_queued_mgmt+0x17c9/0x2ac0 net/mac80211/ibss.c:1642
 ieee80211_iface_process_skb net/mac80211/iface.c:1643 [inline]
 ieee80211_iface_work+0x717/0xc70 net/mac80211/iface.c:1697
 cfg80211_wiphy_work+0x225/0x260 net/wireless/core.c:437
 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 (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/08/29 18:31 linux-6.6.y cc1a1c5b404a 3e1beec6 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: task hung in hfs_mdb_commit
* Struck through repros no longer work on HEAD.