INFO: task hung in nilfs_transaction_begin

Status: upstream: reported C repro on 2026/08/31 00:52
Reported-by: syzbot+e1166ca56819e0faca9f@syzkaller.appspotmail.com
First crash: 11d, last: 11d
▶ ▼ Similar bugs (4)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: task hung in nilfs_transaction_begin nilfs 1 1 961d 961d 0/29 auto-obsoleted due to no activity on 2024/04/23 10:04
upstream INFO: task hung in nilfs_transaction_begin (3) prio:normal nilfs 1 syz, C error 7 10d 57d 26/29 upstream: reported C repro on 2026/07/16 07:51
linux-6.1 INFO: task hung in nilfs_transaction_begin 1 syz, C 2 11d 11d 0/3 upstream: reported C repro on 2026/08/31 11:58
upstream INFO: task hung in nilfs_transaction_begin (2) prio:low nilfs 1 syz, C error 14 96d 136d 29/29 fixed on 2026/07/15 08:27

Sample crash report:
INFO: task syz.2.19:6007 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.2.19        state:D stack:26360 pid:6007  ppid:5930   flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5382 [inline]
 __schedule+0x15ae/0x4660 kernel/sched/core.c:6701
 schedule+0xbd/0x170 kernel/sched/core.c:6775
 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:6834
 rwsem_down_read_slowpath+0x517/0x880 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
 nilfs_transaction_begin+0x364/0x710 fs/nilfs2/segment.c:223
 nilfs_mkdir+0xd7/0x340 fs/nilfs2/namei.c:228
 vfs_mkdir+0x2a5/0x470 fs/namei.c:4168
 do_mkdirat+0x1dc/0x450 fs/namei.c:4191
 __do_sys_mkdirat fs/namei.c:4206 [inline]
 __se_sys_mkdirat fs/namei.c:4204 [inline]
 __x64_sys_mkdirat+0x89/0xa0 fs/namei.c:4204
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f7f2ad9cfc7
RSP: 002b:00007f7f2a3dce58 EFLAGS: 00000246
 ORIG_RAX: 0000000000000102
RAX: ffffffffffffffda RBX: 00007f7f2a3dcee0 RCX: 00007f7f2ad9cfc7
RDX: 00000000000001ff RSI: 0000200000000340 RDI: 00000000ffffff9c
RBP: 0000200000000080 R08: 0000200000000140 R09: 0000000000000000
R10: 0000200000000080 R11: 0000000000000246 R12: 0000200000000340
R13: 00007f7f2a3dcea0 R14: 0000000000000000 R15: 0000000000000000
 </TASK>
INFO: task syz.1.18:6014 blocked for more than 146 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.1.18        state:D
 stack:25936 pid:6014  ppid:5929   flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5382 [inline]
 __schedule+0x15ae/0x4660 kernel/sched/core.c:6701
 schedule+0xbd/0x170 kernel/sched/core.c:6775
 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:6834
 rwsem_down_read_slowpath+0x517/0x880 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
 nilfs_transaction_begin+0x364/0x710 fs/nilfs2/segment.c:223
 nilfs_mkdir+0xd7/0x340 fs/nilfs2/namei.c:228
 vfs_mkdir+0x2a5/0x470 fs/namei.c:4168
 do_mkdirat+0x1dc/0x450 fs/namei.c:4191
 __do_sys_mkdirat fs/namei.c:4206 [inline]
 __se_sys_mkdirat fs/namei.c:4204 [inline]
 __x64_sys_mkdirat+0x89/0xa0 fs/namei.c:4204
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f896579cfc7
RSP: 002b:00007f89666f1e58 EFLAGS: 00000246 ORIG_RAX: 0000000000000102
RAX: ffffffffffffffda RBX: 00007f89666f1ee0 RCX: 00007f896579cfc7
RDX: 00000000000001ff RSI: 0000200000000340 RDI: 00000000ffffff9c
RBP: 0000200000000080 R08: 0000200000000140 R09: 0000000000000000
R10: 0000200000000080 R11: 0000000000000246 R12: 0000200000000340
R13: 00007f89666f1ea0 R14: 0000000000000000 R15: 0000000000000000
 </TASK>
INFO: task syz.0.17:6020 blocked for more than 148 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.17        state:D stack:26504 pid:6020  ppid:5926   flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5382 [inline]
 __schedule+0x15ae/0x4660 kernel/sched/core.c:6701
 schedule+0xbd/0x170 kernel/sched/core.c:6775
 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:6834
 rwsem_down_read_slowpath+0x517/0x880 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
 nilfs_transaction_begin+0x364/0x710 fs/nilfs2/segment.c:223
 nilfs_mkdir+0xd7/0x340 fs/nilfs2/namei.c:228
 vfs_mkdir+0x2a5/0x470 fs/namei.c:4168
 do_mkdirat+0x1dc/0x450 fs/namei.c:4191
 __do_sys_mkdirat fs/namei.c:4206 [inline]
 __se_sys_mkdirat fs/namei.c:4204 [inline]
 __x64_sys_mkdirat+0x89/0xa0 fs/namei.c:4204
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f0f7c19cfc7
RSP: 002b:00007f0f7d000e58 EFLAGS: 00000246
 ORIG_RAX: 0000000000000102
RAX: ffffffffffffffda RBX: 00007f0f7d000ee0 RCX: 00007f0f7c19cfc7
RDX: 00000000000001ff RSI: 0000200000000340 RDI: 00000000ffffff9c
RBP: 0000200000000080 R08: 0000200000000140 R09: 0000000000000000
R10: 0000200000000080 R11: 0000000000000246 R12: 0000200000000340
R13: 00007f0f7d000ea0 R14: 0000000000000000 R15: 0000000000000000
 </TASK>
INFO: task syz.3.20:6022 blocked for more than 150 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.3.20        state:D
 stack:26504 pid:6022  ppid:5936   flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5382 [inline]
 __schedule+0x15ae/0x4660 kernel/sched/core.c:6701
 schedule+0xbd/0x170 kernel/sched/core.c:6775
 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:6834
 rwsem_down_read_slowpath+0x517/0x880 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
 nilfs_transaction_begin+0x364/0x710 fs/nilfs2/segment.c:223
 nilfs_mkdir+0xd7/0x340 fs/nilfs2/namei.c:228
 vfs_mkdir+0x2a5/0x470 fs/namei.c:4168
 do_mkdirat+0x1dc/0x450 fs/namei.c:4191
 __do_sys_mkdirat fs/namei.c:4206 [inline]
 __se_sys_mkdirat fs/namei.c:4204 [inline]
 __x64_sys_mkdirat+0x89/0xa0 fs/namei.c:4204
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f659cd9cfc7
RSP: 002b:00007f659c3fde58 EFLAGS: 00000246
 ORIG_RAX: 0000000000000102
RAX: ffffffffffffffda RBX: 00007f659c3fdee0 RCX: 00007f659cd9cfc7
RDX: 00000000000001ff RSI: 0000200000000340 RDI: 00000000ffffff9c
RBP: 0000200000000080 R08: 0000200000000140 R09: 0000000000000000
R10: 0000200000000080 R11: 0000000000000246 R12: 0000200000000340
R13: 00007f659c3fdea0 R14: 0000000000000000 R15: 0000000000000000
 </TASK>

Showing all locks held in the system:
2 locks held by kworker/u4:0/11:
5 locks held by kworker/u4:1/12:
1 lock held by khungtaskd/29:
 #0: ffffffff8d131da0 (rcu_read_lock
){....}-{1:2}
, at: rcu_lock_acquire include/linux/rcupdate.h:334 [inline]
, at: rcu_read_lock include/linux/rcupdate.h:786 [inline]
, at: debug_show_all_locks+0x55/0x290 kernel/locking/lockdep.c:6633
5 locks held by kworker/u4:4/63:
 #0: ffff88801a25d138 ((wq_completion)netns){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2632 [inline]
 #0: ffff88801a25d138 ((wq_completion)netns){+.+.}-{0:0}, at: process_scheduled_works+0x975/0x1600 kernel/workqueue.c:2734
 #1: ffffc900015d7d00 (net_cleanup_work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2632 [inline]
 #1: ffffc900015d7d00 (net_cleanup_work){+.+.}-{0:0}, at: process_scheduled_works+0x975/0x1600 kernel/workqueue.c:2734
 #2: 
ffffffff8e3c9f90

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/08/31 03:20 linux-6.6.y a4a971135a2f 2f52988a .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-linux-6-6-kasan INFO: task hung in nilfs_transaction_begin
2026/08/31 00:52 linux-6.6.y a4a971135a2f 2f52988a .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: task hung in nilfs_transaction_begin
* Struck through repros no longer work on HEAD.