syzbot


INFO: task hung in ntfs_fallocate

Status: upstream: reported C repro on 2025/12/05 05:04
Subsystems: ntfs3
[Documentation on labels]
Reported-by: syzbot+3829f3f96d42c57315fe@syzkaller.appspotmail.com
First crash: 116d, last: 5d06h
Cause bisection: the cause commit could be any of (bisect log):
  1997cdc3e727 fs/ntfs3: Use variable length array instead of fixed size
  c935c6687886 fs/ntfs3: Redesign ntfs_create_inode to return error code instead of inode
  
Fix bisection: failed (error log, bisect log)
  
Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [ntfs3?] INFO: task hung in ntfs_fallocate 0 (1) 2025/12/05 05:04
Similar bugs (2)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.1 INFO: task hung in ntfs_fallocate 1 1 967d 967d 0/3 auto-obsoleted due to no activity on 2023/11/11 09:02
linux-5.15 INFO: task hung in ntfs_fallocate origin:lts-only 1 C error 11 43d 73d 0/3 upstream: reported C repro on 2026/01/13 10:08
Last patch testing requests (1)
Created Duration User Patch Repo Result
2025/12/15 08:50 16m retest repro upstream report log
Fix bisection attempts (2)
Created Duration User Patch Repo Result
2026/02/24 08:45 0m bisect fix upstream error job log
2026/01/18 05:44 2h19m bisect fix upstream OK (0) job log log

Sample crash report:
INFO: task syz.0.136:6323 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.136       state:D stack:27392 pid:6323  tgid:6321  ppid:5913   task_flags:0x400040 flags:0x00080002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5298 [inline]
 __schedule+0x1553/0x5240 kernel/sched/core.c:6911
 __schedule_loop kernel/sched/core.c:6993 [inline]
 rt_mutex_schedule+0x76/0xf0 kernel/sched/core.c:7289
 rt_mutex_slowlock_block kernel/locking/rtmutex.c:1647 [inline]
 __rt_mutex_slowlock kernel/locking/rtmutex.c:1721 [inline]
 __rt_mutex_slowlock_locked+0x1f8f/0x25c0 kernel/locking/rtmutex.c:1760
 rt_mutex_slowlock+0xbd/0x170 kernel/locking/rtmutex.c:1800
 __rt_mutex_lock kernel/locking/rtmutex.c:1815 [inline]
 rwbase_write_lock+0x14d/0x730 kernel/locking/rwbase_rt.c:244
 inode_lock include/linux/fs.h:1028 [inline]
 ntfs_fallocate+0x2e7/0x1230 fs/ntfs3/file.c:489
 vfs_fallocate+0x672/0x7f0 fs/open.c:340
 ksys_fallocate fs/open.c:364 [inline]
 __do_sys_fallocate fs/open.c:369 [inline]
 __se_sys_fallocate fs/open.c:367 [inline]
 __x64_sys_fallocate+0xc0/0x110 fs/open.c:367
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fc5a844c799
RSP: 002b:00007fc5a7a8d028 EFLAGS: 00000246 ORIG_RAX: 000000000000011d
RAX: ffffffffffffffda RBX: 00007fc5a86c6090 RCX: 00007fc5a844c799
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000004
RBP: 00007fc5a84e2c99 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000008800000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fc5a86c6128 R14: 00007fc5a86c6090 R15: 00007fff91e9d948
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/38:
 #0: ffffffff8ddcb980 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:312 [inline]
 #0: ffffffff8ddcb980 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:850 [inline]
 #0: ffffffff8ddcb980 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6775
2 locks held by getty/5555:
 #0: ffff88803728d0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc90003e8b2e0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x462/0x13c0 drivers/tty/n_tty.c:2211
3 locks held by syz.0.136/6322:
2 locks held by syz.0.136/6323:
 #0: ffff888034f98480 (sb_writers#12){.+.+}-{0:0}, at: file_start_write include/linux/fs.h:2710 [inline]
 #0: ffff888034f98480 (sb_writers#12){.+.+}-{0:0}, at: vfs_fallocate+0x5f9/0x7f0 fs/open.c:339
 #1: ffff88805af49ad8 (&sb->s_type->i_mutex_key#24){+.+.}-{4:4}, at: inode_lock include/linux/fs.h:1028 [inline]
 #1: ffff88805af49ad8 (&sb->s_type->i_mutex_key#24){+.+.}-{4:4}, at: ntfs_fallocate+0x2e7/0x1230 fs/ntfs3/file.c:489
3 locks held by syz.1.184/6487:
2 locks held by syz.1.184/6488:
 #0: ffff8880338ae480 (sb_writers#12){.+.+}-{0:0}, at: file_start_write include/linux/fs.h:2710 [inline]
 #0: ffff8880338ae480 (sb_writers#12){.+.+}-{0:0}, at: vfs_fallocate+0x5f9/0x7f0 fs/open.c:339
 #1: ffff88805acdc928 (&sb->s_type->i_mutex_key#24){+.+.}-{4:4}, at: inode_lock include/linux/fs.h:1028 [inline]
 #1: ffff88805acdc928 (&sb->s_type->i_mutex_key#24){+.+.}-{4:4}, at: ntfs_fallocate+0x2e7/0x1230 fs/ntfs3/file.c:489
4 locks held by syz.2.273/6780:
2 locks held by syz.2.273/6781:
 #0: ffff88802865c480 (sb_writers#12){.+.+}-{0:0}, at: file_start_write include/linux/fs.h:2710 [inline]
 #0: ffff88802865c480 (sb_writers#12){.+.+}-{0:0}, at: vfs_fallocate+0x5f9/0x7f0 fs/open.c:339
 #1: ffff88805ac96fc0 (&sb->s_type->i_mutex_key#24){+.+.}-{4:4}, at: inode_lock include/linux/fs.h:1028 [inline]
 #1: ffff88805ac96fc0 (&sb->s_type->i_mutex_key#24){+.+.}-{4:4}, at: ntfs_fallocate+0x2e7/0x1230 fs/ntfs3/file.c:489
3 locks held by syz.3.348/7032:

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

NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 38 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 nmi_cpu_backtrace+0x274/0x2d0 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x17a/0x300 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:161 [inline]
 __sys_info lib/sys_info.c:157 [inline]
 sys_info+0x135/0x170 lib/sys_info.c:165
 check_hung_uninterruptible_tasks kernel/hung_task.c:346 [inline]
 watchdog+0xfd9/0x1030 kernel/hung_task.c:515
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 6963 Comm: udevd Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
RIP: 0010:rcu_is_watching_curr_cpu include/linux/context_tracking.h:-1 [inline]
RIP: 0010:rcu_is_watching+0x1c/0xb0 kernel/rcu/tree.c:752
Code: 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 41 57 41 56 53 65 ff 05 10 d7 a4 10 e8 8b e3 79 09 89 c3 83 f8 08 73 65 <49> bf 00 00 00 00 00 fc ff df 4c 8d 34 dd 90 47 80 8d 4c 89 f0 48
RSP: 0018:ffffc90006d9f700 EFLAGS: 00000293
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000080000001
RDX: 0000000000000000 RSI: ffffffff8ba671e0 RDI: ffffffff8ba671a0
RBP: 0000000000000001 R08: 0000000000000000 R09: 0000000000000000
R10: dffffc0000000000 R11: ffffed1003389e3c R12: dffffc0000000000
R13: ffff88803c93b180 R14: ffff888033cf2a50 R15: 0000000000000000
FS:  00007f9f64e81880(0000) GS:ffff88812633b000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f85cd196001 CR3: 000000003a45c000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 rcu_read_lock include/linux/rcupdate.h:851 [inline]
 dput+0x70/0x1a0 fs/dcache.c:923
 step_into_slowpath+0x2d4/0x7e0 fs/namei.c:2115
 step_into fs/namei.c:2149 [inline]
 walk_component fs/namei.c:2285 [inline]
 link_path_walk+0xd50/0x18d0 fs/namei.c:2647
 path_openat+0x2d5/0x38a0 fs/namei.c:4826
 do_file_open+0x23e/0x4a0 fs/namei.c:4859
 do_sys_openat2+0x113/0x200 fs/open.c:1366
 do_sys_open fs/open.c:1372 [inline]
 __do_sys_openat fs/open.c:1388 [inline]
 __se_sys_openat fs/open.c:1383 [inline]
 __x64_sys_openat+0x138/0x170 fs/open.c:1383
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f9f64f6f407
Code: 48 89 fa 4c 89 df e8 38 aa 00 00 8b 93 08 03 00 00 59 5e 48 83 f8 fc 74 1a 5b c3 0f 1f 84 00 00 00 00 00 48 8b 44 24 10 0f 05 <5b> c3 0f 1f 80 00 00 00 00 83 e2 39 83 fa 08 75 de e8 23 ff ff ff
RSP: 002b:00007fff1f1f9650 EFLAGS: 00000202 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007f9f64e81880 RCX: 00007f9f64f6f407
RDX: 0000000000080000 RSI: 00007fff1f1f97d0 RDI: ffffffffffffff9c
RBP: 0000000000000008 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 00005577a07797f5
R13: 00005577a07797f5 R14: 0000000000000001 R15: 00007fff1f1fe060
 </TASK>

Crashes (5):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/03/22 07:13 upstream 113ae7b4decc 5b92003d .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-upstream-fs INFO: task hung in ntfs_fallocate
2025/12/01 04:53 upstream e69c7c175115 d6526ea3 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-upstream-fs INFO: task hung in ntfs_fallocate
2026/03/22 03:53 upstream 113ae7b4decc 5b92003d .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs INFO: task hung in ntfs_fallocate
2026/01/25 08:40 upstream 5dbeeb268b63 40acda8a .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs INFO: task hung in ntfs_fallocate
2025/12/01 01:51 upstream e69c7c175115 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs INFO: task hung in ntfs_fallocate
* Struck through repros no longer work on HEAD.