syzbot

INFO: task syz.0.17:6030 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.17        state:D stack:28744 pid:6030  tgid:6028  ppid:5954   task_flags:0x400040 flags:0x00080002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5264 [inline]
 __schedule+0x1848/0x4ec0 kernel/sched/core.c:6872
 __schedule_loop kernel/sched/core.c:6954 [inline]
 schedule+0x165/0x360 kernel/sched/core.c:6969
 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7026
 rwsem_down_write_slowpath+0x872/0xfe0 kernel/locking/rwsem.c:1185
 __down_write_common kernel/locking/rwsem.c:1317 [inline]
 __down_write kernel/locking/rwsem.c:1326 [inline]
 down_write_nested+0x1b5/0x200 kernel/locking/rwsem.c:1707
 inode_lock_nested include/linux/fs.h:1096 [inline]
 do_unlinkat+0x1c7/0x560 fs/namei.c:4724
 __do_sys_unlinkat fs/namei.c:4778 [inline]
 __se_sys_unlinkat fs/namei.c:4771 [inline]
 __x64_sys_unlinkat+0xd3/0xf0 fs/namei.c:4771
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f7be8f8f6c9
RSP: 002b:00007f7be9da0038 EFLAGS: 00000246 ORIG_RAX: 0000000000000107
RAX: ffffffffffffffda RBX: 00007f7be91e6090 RCX: 00007f7be8f8f6c9
RDX: 0000000000000000 RSI: 0000200000000480 RDI: ffffffffffffff9c
RBP: 00007f7be9011f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f7be91e6128 R14: 00007f7be91e6090 R15: 00007fff7125fa68
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/31:
 #0: ffffffff8df3d860 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 #0: ffffffff8df3d860 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:867 [inline]
 #0: ffffffff8df3d860 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6775
2 locks held by getty/5585:
 #0: ffff88803461b0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc9000332b2f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x43e/0x1400 drivers/tty/n_tty.c:2222
3 locks held by syz.0.17/6029:
2 locks held by syz.0.17/6030:
 #0: ffff888078d0a420 (sb_writers#12){.+.+}-{0:0}, at: mnt_want_write+0x41/0x90 fs/namespace.c:498
 #1: ffff88805a016988 (&type->i_mutex_dir_key#8/1){+.+.}-{4:4}, at: inode_lock_nested include/linux/fs.h:1096 [inline]
 #1: ffff88805a016988 (&type->i_mutex_dir_key#8/1){+.+.}-{4:4}, at: do_unlinkat+0x1c7/0x560 fs/namei.c:4724
3 locks held by syz.1.18/6053:
2 locks held by syz.1.18/6054:
 #0: ffff8880742ac420 (sb_writers#12){.+.+}-{0:0}, at: mnt_want_write+0x41/0x90 fs/namespace.c:498
 #1: ffff88805a1f6240 (&type->i_mutex_dir_key#8/1){+.+.}-{4:4}, at: inode_lock_nested include/linux/fs.h:1096 [inline]
 #1: ffff88805a1f6240 (&type->i_mutex_dir_key#8/1){+.+.}-{4:4}, at: do_unlinkat+0x1c7/0x560 fs/namei.c:4724
4 locks held by syz.2.19/6083:
2 locks held by syz.2.19/6084:
 #0: ffff8880739c6420 (sb_writers#12){.+.+}-{0:0}, at: mnt_want_write+0x41/0x90 fs/namespace.c:498
 #1: ffff88802302d3b0 (&type->i_mutex_dir_key#8/1){+.+.}-{4:4}, at: inode_lock_nested include/linux/fs.h:1096 [inline]
 #1: ffff88802302d3b0 (&type->i_mutex_dir_key#8/1){+.+.}-{4:4}, at: do_unlinkat+0x1c7/0x560 fs/namei.c:4724
3 locks held by syz.3.20/6107:
2 locks held by syz.3.20/6108:
 #0: ffff888078578420 (sb_writers#12){.+.+}-{0:0}, at: mnt_want_write+0x41/0x90 fs/namespace.c:498
 #1: ffff888076158398 (&type->i_mutex_dir_key#8/1){+.+.}-{4:4}, at: inode_lock_nested include/linux/fs.h:1096 [inline]
 #1: ffff888076158398 (&type->i_mutex_dir_key#8/1){+.+.}-{4:4}, at: do_unlinkat+0x1c7/0x560 fs/namei.c:4724
3 locks held by syz.4.21/6137:
2 locks held by syz.4.21/6138:
 #0: ffff888020b5e420 (sb_writers#12){.+.+}-{0:0}, at: mnt_want_write+0x41/0x90 fs/namespace.c:498
 #1: ffff88805a289970 (&type->i_mutex_dir_key#8/1){+.+.}-{4:4}, at: inode_lock_nested include/linux/fs.h:1096 [inline]
 #1: ffff88805a289970 (&type->i_mutex_dir_key#8/1){+.+.}-{4:4}, at: do_unlinkat+0x1c7/0x560 fs/namei.c:4724
3 locks held by syz.5.22/6174:
2 locks held by syz.5.22/6175:
 #0: ffff888072e38420 (sb_writers#12){.+.+}-{0:0}, at: mnt_want_write+0x41/0x90 fs/namespace.c:498
 #1: ffff88805a011228 (&type->i_mutex_dir_key#8/1){+.+.}-{4:4}, at: inode_lock_nested include/linux/fs.h:1096 [inline]
 #1: ffff88805a011228 (&type->i_mutex_dir_key#8/1){+.+.}-{4:4}, at: do_unlinkat+0x1c7/0x560 fs/namei.c:4724
3 locks held by syz.6.23/6207:
2 locks held by syz.6.23/6208:
 #0: ffff888077b6c420 (sb_writers#12){.+.+}-{0:0}, at: mnt_want_write+0x41/0x90 fs/namespace.c:498
 #1: ffff88802302f0d0 (&type->i_mutex_dir_key#8/1){+.+.}-{4:4}, at: inode_lock_nested include/linux/fs.h:1096 [inline]
 #1: ffff88802302f0d0 (&type->i_mutex_dir_key#8/1){+.+.}-{4:4}, at: do_unlinkat+0x1c7/0x560 fs/namei.c:4724
3 locks held by syz.7.24/6240:
2 locks held by syz.7.24/6241:
 #0: ffff88807a21a420 (sb_writers#12){.+.+}-{0:0}, at: mnt_want_write+0x41/0x90 fs/namespace.c:498
 #1: ffff88805a1f4520 (&type->i_mutex_dir_key#8/1){+.+.}-{4:4}, at: inode_lock_nested include/linux/fs.h:1096 [inline]
 #1: ffff88805a1f4520 (&type->i_mutex_dir_key#8/1){+.+.}-{4:4}, at: do_unlinkat+0x1c7/0x560 fs/namei.c:4724

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

NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 31 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 nmi_cpu_backtrace+0x39e/0x3d0 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x17a/0x300 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:160 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:336 [inline]
 watchdog+0xfa9/0xff0 kernel/hung_task.c:499
 kthread+0x711/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x599/0xb30 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 6107 Comm: syz.3.20 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
RIP: 0010:__might_sleep+0x39/0x100 kernel/sched/core.c:8754
Code: bf 00 00 00 00 00 fc ff df 65 48 8b 1c 25 08 30 75 92 4c 8d 73 18 4c 89 f0 48 c1 e8 03 42 0f b6 04 38 84 c0 0f 85 90 00 00 00 <41> 8b 2e 85 ed 74 39 48 81 c3 d0 17 00 00 49 89 dd 49 c1 ed 03 43
RSP: 0018:ffffc90002e879d0 EFLAGS: 00000246
RAX: 0000000000000000 RBX: ffff888022afdb80 RCX: ffff888022afdb80
RDX: 0000000000000000 RSI: 00000000000007b4 RDI: ffffffff8b79a060
RBP: ffff888078578000 R08: ffffffff8dc168c3 R09: 1ffffffff1b82d18
R10: dffffc0000000000 R11: fffffbfff1b82d19 R12: ffff88802302e0f8
R13: ffff88802302e178 R14: ffff888022afdb98 R15: dffffc0000000000
FS:  00007fbe15fbb6c0(0000) GS:ffff888125fcd000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00005630577f6a38 CR3: 0000000026f84000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 iput+0x2b/0x1050 fs/inode.c:1972
 insert_inode_locked+0x32a/0x5d0 fs/inode.c:1874
 ntfs_new_inode+0xc8/0x100 fs/ntfs3/fsntfs.c:1688
 ntfs_create_inode+0x606/0x32a0 fs/ntfs3/inode.c:1309
 ntfs_mknod+0x3b/0x50 fs/ntfs3/namei.c:120
 vfs_mknod+0x3da/0x430 fs/namei.c:4322
 do_mknodat+0x3c7/0x530 fs/namei.c:-1
 __do_sys_mknodat fs/namei.c:4400 [inline]
 __se_sys_mknodat fs/namei.c:4397 [inline]
 __x64_sys_mknodat+0xa7/0xc0 fs/namei.c:4397
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fbe1518f6c9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fbe15fbb038 EFLAGS: 00000246 ORIG_RAX: 0000000000000103
RAX: ffffffffffffffda RBX: 00007fbe153e5fa0 RCX: 00007fbe1518f6c9
RDX: 00000000000021c0 RSI: 0000200000000040 RDI: ffffffffffffff9c
RBP: 00007fbe15211f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000103 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fbe153e6038 R14: 00007fbe153e5fa0 R15: 00007ffcaa59b5c8
 </TASK>