syzbot


INFO: task hung in txUnlock

Status: upstream: reported C repro on 2025/07/13 11:46
Bug presence: origin:upstream
[Documentation on labels]
Reported-by: syzbot+1264b21e2fd7b4f80f46@syzkaller.appspotmail.com
First crash: 6d12h, last: 6d12h
Bug presence (1)
Date Name Commit Repro Result
2025/07/18 upstream (ToT) 6832a9317eee C [report] INFO: task hung in release_metapage

Sample crash report:
INFO: task jfsCommit:277 blocked for more than 143 seconds.
      Not tainted 5.15.187-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:jfsCommit       state:D stack:28096 pid:  277 ppid:     2 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5030 [inline]
 __schedule+0x11b8/0x43b0 kernel/sched/core.c:6376
 schedule+0x11b/0x1e0 kernel/sched/core.c:6459
 io_schedule+0x7c/0xd0 kernel/sched/core.c:8484
 wait_on_page_bit_common+0x815/0xe00 mm/filemap.c:1356
 txUnlock+0x244/0xcb0 fs/jfs/jfs_txnmgr.c:929
 txLazyCommit fs/jfs/jfs_txnmgr.c:2716 [inline]
 jfs_lazycommit+0x583/0xb20 fs/jfs/jfs_txnmgr.c:2766
 kthread+0x436/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>
INFO: task syz.0.16:4313 blocked for more than 143 seconds.
      Not tainted 5.15.187-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.16        state:D stack:24960 pid: 4313 ppid:  4294 flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5030 [inline]
 __schedule+0x11b8/0x43b0 kernel/sched/core.c:6376
 schedule+0x11b/0x1e0 kernel/sched/core.c:6459
 io_schedule+0x7c/0xd0 kernel/sched/core.c:8484
 wait_on_page_bit_common+0x815/0xe00 mm/filemap.c:1356
 lock_page include/linux/pagemap.h:625 [inline]
 release_metapage+0x11f/0xe10 fs/jfs/jfs_metapage.c:736
 discard_metapage fs/jfs/jfs_metapage.h:88 [inline]
 __get_metapage+0xbeb/0x1060 fs/jfs/jfs_metapage.c:645
 dtSearch+0x5d5/0x2050 fs/jfs/jfs_dtree.c:624
 jfs_lookup+0x152/0x380 fs/jfs/namei.c:1459
 __lookup_slow+0x27d/0x3d0 fs/namei.c:1663
 lookup_slow+0x53/0x70 fs/namei.c:1680
 walk_component+0x319/0x460 fs/namei.c:1976
 lookup_last fs/namei.c:2431 [inline]
 path_lookupat+0x169/0x440 fs/namei.c:2455
 filename_lookup+0x1e2/0x4f0 fs/namei.c:2484
 user_path_at_empty+0x40/0x190 fs/namei.c:2883
 user_path_at include/linux/namei.h:57 [inline]
 __do_sys_chdir fs/open.c:490 [inline]
 __se_sys_chdir+0x91/0x280 fs/open.c:484
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f7c3f7cb929
RSP: 002b:00007fff747f3fa8 EFLAGS: 00000246 ORIG_RAX: 0000000000000050
RAX: ffffffffffffffda RBX: 00007f7c3f9f2fa0 RCX: 00007f7c3f7cb929
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000200000000a40
RBP: 00007f7c3f84db39 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f7c3f9f2fa0 R14: 00007f7c3f9f2fa0 R15: 0000000000000001
 </TASK>

Showing all locks held in the system:
3 locks held by kworker/1:0/21:
 #0: ffff888016870938 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x760/0x1000 kernel/workqueue.c:-1
 #1: ffffc90000db7d00 ((work_completion)(&data->fib_event_work)){+.+.}-{0:0}, at: process_one_work+0x7a3/0x1000 kernel/workqueue.c:2285
 #2: ffff888051a9a240 (&data->fib_lock){+.+.}-{3:3}, at: nsim_fib_event_work+0x271/0x3240 drivers/net/netdevsim/fib.c:1480
1 lock held by khungtaskd/27:
 #0: ffffffff8c11c2e0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x0/0x30
3 locks held by kworker/u4:2/154:
 #0: ffff8880b913a318 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x26/0x140 kernel/sched/core.c:475
 #1: ffff8880b9127848 (&per_cpu_ptr(group->pcpu, cpu)->seq){-.-.}-{0:0}, at: psi_task_switch+0x4d6/0x810 kernel/sched/psi.c:891
 #2: ffff88802ab3cd40 (&wdev->mtx){+.+.}-{3:3}, at: sdata_lock net/mac80211/ieee80211_i.h:1036 [inline]
 #2: ffff88802ab3cd40 (&wdev->mtx){+.+.}-{3:3}, at: ieee80211_ibss_work+0xa0/0x10b0 net/mac80211/ibss.c:1685
2 locks held by getty/3946:
 #0: ffff88814ce51098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:252
 #1: ffffc90002cf62e8 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x5ba/0x1a30 drivers/tty/n_tty.c:2158
1 lock held by syz.0.16/4313:
 #0: ffff8880692a2a80 (&type->i_mutex_dir_key#8){.+.+}-{3:3}, at: inode_lock_shared include/linux/fs.h:797 [inline]
 #0: ffff8880692a2a80 (&type->i_mutex_dir_key#8){.+.+}-{3:3}, at: lookup_slow+0x46/0x70 fs/namei.c:1679
2 locks held by kworker/u4:5/4314:
 #0: ffff8880b913a318 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x26/0x140 kernel/sched/core.c:475
 #1: ffff8880b9127848 (&per_cpu_ptr(group->pcpu, cpu)->seq){-.-.}-{0:0}, at: psi_task_switch+0x495/0x810 kernel/sched/psi.c:882
1 lock held by syz.1.17/4338:
 #0: ffff888069c02a80 (&type->i_mutex_dir_key#8){.+.+}-{3:3}, at: inode_lock_shared include/linux/fs.h:797 [inline]
 #0: ffff888069c02a80 (&type->i_mutex_dir_key#8){.+.+}-{3:3}, at: lookup_slow+0x46/0x70 fs/namei.c:1679
1 lock held by syz.2.18/4367:
 #0: ffff888069c058c0 (&type->i_mutex_dir_key#8){.+.+}-{3:3}, at: inode_lock_shared include/linux/fs.h:797 [inline]
 #0: ffff888069c058c0 (&type->i_mutex_dir_key#8){.+.+}-{3:3}, at: lookup_slow+0x46/0x70 fs/namei.c:1679
1 lock held by syz.3.19/4388:
 #0: ffff8880692a6b40 (&type->i_mutex_dir_key#8){.+.+}-{3:3}, at: inode_lock_shared include/linux/fs.h:797 [inline]
 #0: ffff8880692a6b40 (&type->i_mutex_dir_key#8){.+.+}-{3:3}, at: lookup_slow+0x46/0x70 fs/namei.c:1679
1 lock held by syz.4.20/4414:
 #0: ffff888069332a80 (&type->i_mutex_dir_key#8){.+.+}-{3:3}, at: inode_lock_shared include/linux/fs.h:797 [inline]
 #0: ffff888069332a80 (&type->i_mutex_dir_key#8){.+.+}-{3:3}, at: lookup_slow+0x46/0x70 fs/namei.c:1679
1 lock held by syz.5.21/4440:
 #0: ffff888069333d00 (&type->i_mutex_dir_key#8){.+.+}-{3:3}, at: inode_lock_shared include/linux/fs.h:797 [inline]
 #0: ffff888069333d00 (&type->i_mutex_dir_key#8){.+.+}-{3:3}, at: lookup_slow+0x46/0x70 fs/namei.c:1679
1 lock held by syz.6.22/4474:
 #0: ffff888069336b40 (&type->i_mutex_dir_key#8){.+.+}-{3:3}, at: inode_lock_shared include/linux/fs.h:797 [inline]
 #0: ffff888069336b40 (&type->i_mutex_dir_key#8){.+.+}-{3:3}, at: lookup_slow+0x46/0x70 fs/namei.c:1679
1 lock held by syz.7.23/4501:
 #0: ffff888069e52a80 (&type->i_mutex_dir_key#8){.+.+}-{3:3}, at: inode_lock_shared include/linux/fs.h:797 [inline]
 #0: ffff888069e52a80 (&type->i_mutex_dir_key#8){.+.+}-{3:3}, at: lookup_slow+0x46/0x70 fs/namei.c:1679
1 lock held by syz.8.24/4528:
 #0: ffff888069173d00 (&type->i_mutex_dir_key#8){.+.+}-{3:3}, at: inode_lock_shared include/linux/fs.h:797 [inline]
 #0: ffff888069173d00 (&type->i_mutex_dir_key#8){.+.+}-{3:3}, at: lookup_slow+0x46/0x70 fs/namei.c:1679
1 lock held by syz.9.25/4561:
 #0: ffff888069e558c0 (&type->i_mutex_dir_key#8){.+.+}-{3:3}, at: inode_lock_shared include/linux/fs.h:797 [inline]
 #0: ffff888069e558c0 (&type->i_mutex_dir_key#8){.+.+}-{3:3}, at: lookup_slow+0x46/0x70 fs/namei.c:1679

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

NMI backtrace for cpu 0
CPU: 0 PID: 27 Comm: khungtaskd Not tainted 5.15.187-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x168/0x230 lib/dump_stack.c:106
 nmi_cpu_backtrace+0x397/0x3d0 lib/nmi_backtrace.c:111
 nmi_trigger_cpumask_backtrace+0x163/0x280 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:148 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:212 [inline]
 watchdog+0xe0f/0xe50 kernel/hung_task.c:369
 kthread+0x436/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 23 Comm: kworker/1:1 Not tainted 5.15.187-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Workqueue: events nsim_dev_trap_report_work
RIP: 0010:_compound_head include/linux/page-flags.h:196 [inline]
RIP: 0010:PageSlab include/linux/page-flags.h:356 [inline]
RIP: 0010:kfree+0x89/0x2a0 mm/slub.c:4555
Code: e8 7c ae 78 ff 49 89 c7 49 c1 ef 06 49 83 e7 c0 48 b9 00 00 00 00 00 ea ff ff 49 8b 44 0f 08 a8 01 0f 85 21 01 00 00 49 01 cf <49> 8b 47 08 4c 89 f9 a8 01 0f 85 1a 01 00 00 48 83 39 ff 49 8b 47
RSP: 0018:ffffc90000ddfa38 EFLAGS: 00000286
RAX: ffffea0001e73a00 RBX: ffff888079cec000 RCX: ffffea0000000000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: dffffc0000000000 R09: fffffbfff1ad3046
R10: fffffbfff1ad3046 R11: 1ffffffff1ad3045 R12: ffff88807d9877fe
R13: dffffc0000000000 R14: ffffffff87d034ce R15: ffffea0001e73a00
FS:  0000000000000000(0000) GS:ffff8880b9100000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f65ce47d000 CR3: 000000001e329000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 skb_free_head net/core/skbuff.c:655 [inline]
 skb_release_data+0x6fe/0x850 net/core/skbuff.c:677
 skb_release_all net/core/skbuff.c:742 [inline]
 __kfree_skb net/core/skbuff.c:756 [inline]
 consume_skb+0xa2/0x100 net/core/skbuff.c:914
 nsim_dev_trap_report drivers/net/netdevsim/dev.c:737 [inline]
 nsim_dev_trap_report_work+0x7cb/0xb40 drivers/net/netdevsim/dev.c:762
 process_one_work+0x863/0x1000 kernel/workqueue.c:2310
 worker_thread+0xaa8/0x12a0 kernel/workqueue.c:2457
 kthread+0x436/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/07/13 11:46 linux-5.15.y 2f693b607545 3cda49cf .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci2-linux-5-15-kasan INFO: task hung in txUnlock
* Struck through repros no longer work on HEAD.