syzbot


INFO: task hung in lmLogClose

Status: upstream: reported C repro on 2025/07/25 07:32
Bug presence: origin:upstream
[Documentation on labels]
Reported-by: syzbot+0347eab37b822a8ac6e5@syzkaller.appspotmail.com
First crash: 83d, last: 29d
Bug presence (1)
Date Name Commit Repro Result
2025/09/17 upstream (ToT) 5aca7966d2a7 C [report] INFO: task hung in lmLogClose
Similar bugs (5)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: task hung in lmLogClose jfs 1 1 912d 912d 0/29 auto-obsoleted due to no activity on 2023/07/16 16:14
upstream INFO: task hung in lmLogClose (3) jfs 1 C error 730 1d15h 576d 0/29 upstream: reported C repro on 2024/03/19 10:13
linux-6.1 INFO: task hung in lmLogClose origin:upstream 1 C 41 5d07h 522d 0/3 upstream: reported C repro on 2024/05/12 07:21
upstream INFO: task hung in lmLogClose (2) jfs 1 C inconclusive done 5 645d 737d 25/29 fixed on 2024/02/24 00:02
linux-5.15 INFO: task hung in lmLogClose origin:upstream 1 C 51 21d 559d 0/3 upstream: reported C repro on 2024/04/05 11:21

Sample crash report:
INFO: task syz-executor:5905 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:21640 pid:5905  ppid:1      flags:0x00004006
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
 lmLogClose+0xb4/0x520 fs/jfs/jfs_logmgr.c:1444
 jfs_umount+0x2ef/0x3c0 fs/jfs/jfs_umount.c:114
 jfs_put_super+0x8c/0x190 fs/jfs/super.c:194
 generic_shutdown_super+0x134/0x2b0 fs/super.c:693
 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+0xf6/0x180 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: 0033:0x7fb9ac18fed7
RSP: 002b:00007fff77a31188 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 00007fb9ac211c05 RCX: 00007fb9ac18fed7
RDX: 0000000000000000 RSI: 0000000000000009 RDI: 00007fff77a31240
RBP: 00007fff77a31240 R08: 0000000000000000 R09: 0000000000000000
R10: 00000000ffffffff R11: 0000000000000246 R12: 00007fff77a322d0
R13: 00007fb9ac211c05 R14: 00000000000198bb R15: 00007fff77a32310
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/29:
 #0: ffffffff8cd2fe20 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:334 [inline]
 #0: ffffffff8cd2fe20 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:786 [inline]
 #0: ffffffff8cd2fe20 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x55/0x290 kernel/locking/lockdep.c:6633
2 locks held by kworker/u4:2/31:
2 locks held by getty/5547:
 #0: ffff88814c4df0a0 (&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 syz-executor/5905:
 #0: ffff88807c4c60e0 (&type->s_umount_key#56){+.+.}-{3:3}, at: __super_lock fs/super.c:56 [inline]
 #0: ffff88807c4c60e0 (&type->s_umount_key#56){+.+.}-{3:3}, at: __super_lock_excl fs/super.c:71 [inline]
 #0: ffff88807c4c60e0 (&type->s_umount_key#56){+.+.}-{3:3}, at: deactivate_super+0xa4/0xe0 fs/super.c:513
 #1: ffffffff8d148728 (jfs_log_mutex){+.+.}-{3:3}, at: lmLogClose+0xb4/0x520 fs/jfs/jfs_logmgr.c:1444
2 locks held by syz-executor/5912:
 #0: ffff88801eb180e0 (&type->s_umount_key#56){+.+.}-{3:3}, at: __super_lock fs/super.c:56 [inline]
 #0: ffff88801eb180e0 (&type->s_umount_key#56){+.+.}-{3:3}, at: __super_lock_excl fs/super.c:71 [inline]
 #0: ffff88801eb180e0 (&type->s_umount_key#56){+.+.}-{3:3}, at: deactivate_super+0xa4/0xe0 fs/super.c:513
 #1: ffffffff8d148728 (jfs_log_mutex){+.+.}-{3:3}, at: lmLogClose+0xb4/0x520 fs/jfs/jfs_logmgr.c:1444
2 locks held by syz-executor/6024:
 #0: ffff8880613f60e0 (&type->s_umount_key#56){+.+.}-{3:3}, at: __super_lock fs/super.c:56 [inline]
 #0: ffff8880613f60e0 (&type->s_umount_key#56){+.+.}-{3:3}, at: __super_lock_excl fs/super.c:71 [inline]
 #0: ffff8880613f60e0 (&type->s_umount_key#56){+.+.}-{3:3}, at: deactivate_super+0xa4/0xe0 fs/super.c:513
 #1: ffffffff8d148728 (jfs_log_mutex){+.+.}-{3:3}, at: lmLogClose+0xb4/0x520 fs/jfs/jfs_logmgr.c:1444
2 locks held by syz-executor/6025:
 #0: ffff88807b4800e0 (&type->s_umount_key#56){+.+.}-{3:3}, at: __super_lock fs/super.c:56 [inline]
 #0: ffff88807b4800e0 (&type->s_umount_key#56){+.+.}-{3:3}, at: __super_lock_excl fs/super.c:71 [inline]
 #0: ffff88807b4800e0 (&type->s_umount_key#56){+.+.}-{3:3}, at: deactivate_super+0xa4/0xe0 fs/super.c:513
 #1: ffffffff8d148728 (jfs_log_mutex){+.+.}-{3:3}, at: lmLogClose+0xb4/0x520 fs/jfs/jfs_logmgr.c:1444
2 locks held by syz-executor/6045:
 #0: ffff88805a1060e0 (&type->s_umount_key#56){+.+.}-{3:3}, at: __super_lock fs/super.c:56 [inline]
 #0: ffff88805a1060e0 (&type->s_umount_key#56){+.+.}-{3:3}, at: __super_lock_excl fs/super.c:71 [inline]
 #0: ffff88805a1060e0 (&type->s_umount_key#56){+.+.}-{3:3}, at: deactivate_super+0xa4/0xe0 fs/super.c:513
 #1: ffffffff8d148728 (jfs_log_mutex){+.+.}-{3:3}, at: lmLogClose+0xb4/0x520 fs/jfs/jfs_logmgr.c:1444
2 locks held by syz-executor/6046:
 #0: ffff8880609240e0 (&type->s_umount_key#56){+.+.}-{3:3}, at: __super_lock fs/super.c:56 [inline]
 #0: ffff8880609240e0 (&type->s_umount_key#56){+.+.}-{3:3}, at: __super_lock_excl fs/super.c:71 [inline]
 #0: ffff8880609240e0 (&type->s_umount_key#56){+.+.}-{3:3}, at: deactivate_super+0xa4/0xe0 fs/super.c:513
 #1: ffffffff8d148728 (jfs_log_mutex){+.+.}-{3:3}, at: lmLogClose+0xb4/0x520 fs/jfs/jfs_logmgr.c:1444
2 locks held by syz-executor/6134:
 #0: ffff88807b5280e0 (&type->s_umount_key#56){+.+.}-{3:3}, at: __super_lock fs/super.c:56 [inline]
 #0: ffff88807b5280e0 (&type->s_umount_key#56){+.+.}-{3:3}, at: __super_lock_excl fs/super.c:71 [inline]
 #0: ffff88807b5280e0 (&type->s_umount_key#56){+.+.}-{3:3}, at: deactivate_super+0xa4/0xe0 fs/super.c:513
 #1: ffffffff8d148728 (jfs_log_mutex){+.+.}-{3:3}, at: lmLogClose+0xb4/0x520 fs/jfs/jfs_logmgr.c:1444
2 locks held by syz-executor/6135:
 #0: ffff88804e80a0e0 (&type->s_umount_key#56){+.+.}-{3:3}, at: __super_lock fs/super.c:56 [inline]
 #0: ffff88804e80a0e0 (&type->s_umount_key#56){+.+.}-{3:3}, at: __super_lock_excl fs/super.c:71 [inline]
 #0: ffff88804e80a0e0 (&type->s_umount_key#56){+.+.}-{3:3}, at: deactivate_super+0xa4/0xe0 fs/super.c:513
 #1: ffffffff8d148728 (jfs_log_mutex){+.+.}-{3:3}, at: lmLogClose+0xb4/0x520 fs/jfs/jfs_logmgr.c:1444
1 lock held by udevd/6137:
1 lock held by syz-executor/6155:
 #0: ffff88805e2680e0 (&type->s_umount_key#56){+.+.}-{3:3}, at: __super_lock fs/super.c:56 [inline]
 #0: ffff88805e2680e0 (&type->s_umount_key#56){+.+.}-{3:3}, at: __super_lock_excl fs/super.c:71 [inline]
 #0: ffff88805e2680e0 (&type->s_umount_key#56){+.+.}-{3:3}, at: deactivate_super+0xa4/0xe0 fs/super.c:513
2 locks held by syz-executor/6156:
 #0: ffff8880500f80e0 (&type->s_umount_key#56){+.+.}-{3:3}, at: __super_lock fs/super.c:56 [inline]
 #0: ffff8880500f80e0 (&type->s_umount_key#56){+.+.}-{3:3}, at: __super_lock_excl fs/super.c:71 [inline]
 #0: ffff8880500f80e0 (&type->s_umount_key#56){+.+.}-{3:3}, at: deactivate_super+0xa4/0xe0 fs/super.c:513
 #1: ffffffff8d148728 (jfs_log_mutex){+.+.}-{3:3}, at: lmLogClose+0xb4/0x520 fs/jfs/jfs_logmgr.c:1444
1 lock held by udevd/6256:
2 locks held by syz.4.364/6656:
2 locks held by dhcpcd/6657:
 #0: ffff88807ee52130 (sk_lock-AF_PACKET){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1731 [inline]
 #0: ffff88807ee52130 (sk_lock-AF_PACKET){+.+.}-{0:0}, at: packet_do_bind+0x32/0xcc0 net/packet/af_packet.c:3258
 #1: ffffffff8cd35df8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:292 [inline]
 #1: ffffffff8cd35df8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x448/0x830 kernel/rcu/tree_exp.h:1004
2 locks held by dhcpcd/6658:
 #0: ffff88807ee54130 (sk_lock-AF_PACKET){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1731 [inline]
 #0: ffff88807ee54130 (sk_lock-AF_PACKET){+.+.}-{0:0}, at: packet_do_bind+0x32/0xcc0 net/packet/af_packet.c:3258
 #1: ffffffff8cd35df8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:324 [inline]
 #1: ffffffff8cd35df8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x360/0x830 kernel/rcu/tree_exp.h:1004
1 lock held by dhcpcd/6659:
 #0: ffff8880599c0130 (sk_lock-AF_PACKET){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1731 [inline]
 #0: ffff8880599c0130 (sk_lock-AF_PACKET){+.+.}-{0:0}, at: packet_do_bind+0x32/0xcc0 net/packet/af_packet.c:3258
2 locks held by syz.5.365/6660:
1 lock held by dhcpcd/6661:
 #0: ffff88804e826130 (sk_lock-AF_PACKET){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1731 [inline]
 #0: ffff88804e826130 (sk_lock-AF_PACKET){+.+.}-{0:0}, at: packet_do_bind+0x32/0xcc0 net/packet/af_packet.c:3258
2 locks held by syz.1.366/6662:
1 lock held by dhcpcd/6663:
 #0: ffff88802fb0a130 (sk_lock-AF_PACKET){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1731 [inline]
 #0: ffff88802fb0a130 (sk_lock-AF_PACKET){+.+.}-{0:0}, at: packet_do_bind+0x32/0xcc0 net/packet/af_packet.c:3258
1 lock held by syz.3.367/6664:

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

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 08/18/2025
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: 31 Comm: kworker/u4:2 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
Workqueue: events_unbound nsim_dev_trap_report_work
RIP: 0010:check_kcov_mode kernel/kcov.c:184 [inline]
RIP: 0010:__sanitizer_cov_trace_pc+0x30/0x60 kernel/kcov.c:216
Code: 04 24 65 48 8b 0d b0 29 7e 7e 65 8b 15 b1 29 7e 7e 81 e2 00 01 ff 00 74 11 81 fa 00 01 00 00 75 35 83 b9 1c 16 00 00 00 74 2c <8b> 91 f8 15 00 00 83 fa 02 75 21 48 8b 91 00 16 00 00 48 8b 32 48
RSP: 0018:ffffc90000a7f1c0 EFLAGS: 00000246
RAX: ffffffff813ad8f9 RBX: ffffc90000a7fac0 RCX: ffff88801ca5bc00
RDX: 0000000000000000 RSI: 0000000000000001 RDI: ffffc90000a7fac0
RBP: ffffc90000a7fac0 R08: ffff88801ca5bc00 R09: 0000000000000003
R10: 0000000000000004 R11: 0000000000000000 R12: ffffc90000a80000
R13: 1ffff9200014fe63 R14: ffffc90000a78000 R15: dffffc0000000000
FS:  0000000000000000(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f8c88721000 CR3: 000000000cb30000 CR4: 00000000003506f0
Call Trace:
 <TASK>
 __read_once_word_nocheck+0x9/0x10 include/asm-generic/rwonce.h:66
 deref_stack_reg+0x1bd/0x240 arch/x86/kernel/unwind_orc.c:406
 unwind_next_frame+0x1789/0x2970 arch/x86/kernel/unwind_orc.c:648
 arch_stack_walk+0x144/0x190 arch/x86/kernel/stacktrace.c:25
 stack_trace_save+0x9c/0xe0 kernel/stacktrace.c:122
 save_stack+0xf7/0x1f0 mm/page_owner.c:128
 __set_page_owner+0x1d/0x60 mm/page_owner.c:192
 set_page_owner include/linux/page_owner.h:31 [inline]
 post_alloc_hook+0x1cd/0x210 mm/page_alloc.c:1554
 prep_new_page mm/page_alloc.c:1561 [inline]
 get_page_from_freelist+0x195c/0x19f0 mm/page_alloc.c:3191
 __alloc_pages+0x1e3/0x460 mm/page_alloc.c:4457
 alloc_slab_page+0x5d/0x170 mm/slub.c:1881
 allocate_slab mm/slub.c:2028 [inline]
 new_slab+0x87/0x2e0 mm/slub.c:2081
 ___slab_alloc+0xc6d/0x1300 mm/slub.c:3253
 __slab_alloc mm/slub.c:3339 [inline]
 __slab_alloc_node mm/slub.c:3392 [inline]
 slab_alloc_node mm/slub.c:3485 [inline]
 __kmem_cache_alloc_node+0x1a2/0x260 mm/slub.c:3534
 __do_kmalloc_node mm/slab_common.c:1006 [inline]
 __kmalloc_node_track_caller+0xa2/0x230 mm/slab_common.c:1027
 kmalloc_reserve+0x117/0x260 net/core/skbuff.c:581
 __alloc_skb+0x138/0x2c0 net/core/skbuff.c:650
 alloc_skb include/linux/skbuff.h:1284 [inline]
 nsim_dev_trap_skb_build drivers/net/netdevsim/dev.c:748 [inline]
 nsim_dev_trap_report drivers/net/netdevsim/dev.c:805 [inline]
 nsim_dev_trap_report_work+0x293/0xb00 drivers/net/netdevsim/dev.c:851
 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 (5):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/09/16 15:49 linux-6.6.y 60a9e718726f e2beed91 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci2-linux-6-6-kasan INFO: task hung in lmLogClose
2025/09/16 10:11 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 lmLogClose
2025/09/04 23:23 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 lmLogClose
2025/08/18 02:25 linux-6.6.y bb9c90ab9c5a 1804e95e .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: task hung in lmLogClose
2025/07/25 07:31 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 lmLogClose
* Struck through repros no longer work on HEAD.