======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Tainted: G             L     
------------------------------------------------------
syz.4.10139/5930 is trying to acquire lock:
ffff88807a0b1c80 (&of->mutex){+.+.}-{4:4}, at: kernfs_fop_write_iter+0x2c2/0x5f0 fs/kernfs/file.c:336

but task is already holding lock:
ffff88807d25d460 (&pipe->mutex){+.+.}-{4:4}, at: pipe_lock fs/pipe.c:91 [inline]
ffff88807d25d460 (&pipe->mutex){+.+.}-{4:4}, at: pipe_lock+0x69/0x80 fs/pipe.c:88

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 (&pipe->mutex){+.+.}-{4:4}:
       lock_acquire kernel/locking/lockdep.c:5942 [inline]
       lock_acquire+0x1d1/0x380 kernel/locking/lockdep.c:5899
       __mutex_lock_common kernel/locking/mutex.c:646 [inline]
       __mutex_lock+0x1a4/0x1bd0 kernel/locking/mutex.c:821
       anon_pipe_prefill_and_lock+0x16c/0x580 fs/pipe.c:165
       anon_pipe_write+0x164/0x1b50 fs/pipe.c:534
       __kernel_write_iter+0x6bb/0x930 fs/read_write.c:621
       __kernel_write+0xf6/0x140 fs/read_write.c:641
       autofs_write fs/autofs/waitq.c:57 [inline]
       autofs_notify_daemon+0x50d/0xd90 fs/autofs/waitq.c:164
       autofs_wait+0x10fd/0x1b50 fs/autofs/waitq.c:426
       autofs_mount_wait+0x132/0x3b0 fs/autofs/root.c:256
       autofs_d_automount+0x490/0x950 fs/autofs/root.c:410
       follow_automount fs/namei.c:1565 [inline]
       __traverse_mounts+0x1b9/0x8a0 fs/namei.c:1618
       traverse_mounts fs/namei.c:1647 [inline]
       handle_mounts fs/namei.c:1749 [inline]
       step_into_slowpath+0xb7e/0xf90 fs/namei.c:2104
       step_into fs/namei.c:2152 [inline]
       walk_component fs/namei.c:2288 [inline]
       lookup_last fs/namei.c:2789 [inline]
       path_lookupat+0x58b/0xc40 fs/namei.c:2813
       filename_lookup+0x202/0x590 fs/namei.c:2842
       vfs_statx+0xff/0x3f0 fs/stat.c:353
       vfs_fstatat fs/stat.c:373 [inline]
       vfs_lstat include/linux/fs.h:3241 [inline]
       __do_sys_newlstat+0xaa/0x130 fs/stat.c:524
       do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
       do_syscall_64+0x123/0x790 arch/x86/entry/syscall_64.c:84
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #1 (&sbi->pipe_mutex){+.+.}-{4:4}:
       lock_acquire kernel/locking/lockdep.c:5942 [inline]
       lock_acquire+0x1d1/0x380 kernel/locking/lockdep.c:5899
       __mutex_lock_common kernel/locking/mutex.c:646 [inline]
       __mutex_lock+0x1a4/0x1bd0 kernel/locking/mutex.c:821
       autofs_write fs/autofs/waitq.c:55 [inline]
       autofs_notify_daemon+0x4f8/0xd90 fs/autofs/waitq.c:164
       autofs_wait+0x10fd/0x1b50 fs/autofs/waitq.c:426
       autofs_mount_wait+0x132/0x3b0 fs/autofs/root.c:256
       autofs_d_automount+0x490/0x950 fs/autofs/root.c:410
       follow_automount fs/namei.c:1565 [inline]
       __traverse_mounts+0x1b9/0x8a0 fs/namei.c:1618
       traverse_mounts fs/namei.c:1647 [inline]
       handle_mounts fs/namei.c:1749 [inline]
       step_into_slowpath+0xb7e/0xf90 fs/namei.c:2104
       step_into fs/namei.c:2152 [inline]
       walk_component fs/namei.c:2288 [inline]
       lookup_last fs/namei.c:2789 [inline]
       path_lookupat+0x58b/0xc40 fs/namei.c:2813
       filename_lookup+0x202/0x590 fs/namei.c:2842
       kern_path+0x37/0x50 fs/namei.c:3036
       lookup_bdev+0xd8/0x2a0 block/bdev.c:1268
       resume_store+0x1d6/0x460 kernel/power/hibernate.c:1278
       kobj_attr_store+0x58/0x80 lib/kobject.c:842
       sysfs_kf_write+0xf2/0x150 fs/sysfs/file.c:145
       kernfs_fop_write_iter+0x3e0/0x5f0 fs/kernfs/file.c:345
       new_sync_write fs/read_write.c:595 [inline]
       vfs_write+0x6af/0x1050 fs/read_write.c:687
       ksys_write+0x12a/0x250 fs/read_write.c:739
       do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
       do_syscall_64+0x123/0x790 arch/x86/entry/syscall_64.c:84
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #0 (&of->mutex){+.+.}-{4:4}:
       check_prev_add+0xeb/0xe60 kernel/locking/lockdep.c:3209
       check_prevs_add kernel/locking/lockdep.c:3328 [inline]
       validate_chain kernel/locking/lockdep.c:3952 [inline]
       __lock_acquire+0x1528/0x1f40 kernel/locking/lockdep.c:5288
       lock_acquire kernel/locking/lockdep.c:5942 [inline]
       lock_acquire+0x1d1/0x380 kernel/locking/lockdep.c:5899
       __mutex_lock_common kernel/locking/mutex.c:646 [inline]
       __mutex_lock+0x1a4/0x1bd0 kernel/locking/mutex.c:821
       kernfs_fop_write_iter+0x2c2/0x5f0 fs/kernfs/file.c:336
       iter_file_splice_write+0x830/0x10b0 fs/splice.c:736
       do_splice_from fs/splice.c:936 [inline]
       do_splice+0x109c/0x1fa0 fs/splice.c:1349
       __do_splice+0x33b/0x370 fs/splice.c:1431
       __do_sys_splice fs/splice.c:1634 [inline]
       __se_sys_splice fs/splice.c:1616 [inline]
       __x64_sys_splice+0x187/0x250 fs/splice.c:1616
       do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
       do_syscall_64+0x123/0x790 arch/x86/entry/syscall_64.c:84
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

other info that might help us debug this:

Chain exists of:
  &of->mutex --> &sbi->pipe_mutex --> &pipe->mutex

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&pipe->mutex);
                               lock(&sbi->pipe_mutex);
                               lock(&pipe->mutex);
  lock(&of->mutex);

 *** DEADLOCK ***

locks held by syz.4.10139/5930: 2, last CPU#0:
 #0: ffff88802d944460 (sb_writers#11){.+.+}-{0:0}, at: __do_splice+0x33b/0x370 fs/splice.c:1431
 #1: ffff88807d25d460 (&pipe->mutex){+.+.}-{4:4}, at: pipe_lock fs/pipe.c:91 [inline]
 #1: ffff88807d25d460 (&pipe->mutex){+.+.}-{4:4}, at: pipe_lock+0x69/0x80 fs/pipe.c:88

stack backtrace:
CPU: 0 UID: 0 PID: 5930 Comm: syz.4.10139 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/05/2026
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120
 print_circular_bug.cold+0x178/0x1be kernel/locking/lockdep.c:2087
 check_noncircular+0x146/0x160 kernel/locking/lockdep.c:2219
 check_prev_add+0xeb/0xe60 kernel/locking/lockdep.c:3209
 check_prevs_add kernel/locking/lockdep.c:3328 [inline]
 validate_chain kernel/locking/lockdep.c:3952 [inline]
 __lock_acquire+0x1528/0x1f40 kernel/locking/lockdep.c:5288
 lock_acquire kernel/locking/lockdep.c:5942 [inline]
 lock_acquire+0x1d1/0x380 kernel/locking/lockdep.c:5899
 __mutex_lock_common kernel/locking/mutex.c:646 [inline]
 __mutex_lock+0x1a4/0x1bd0 kernel/locking/mutex.c:821
 kernfs_fop_write_iter+0x2c2/0x5f0 fs/kernfs/file.c:336
 iter_file_splice_write+0x830/0x10b0 fs/splice.c:736
 do_splice_from fs/splice.c:936 [inline]
 do_splice+0x109c/0x1fa0 fs/splice.c:1349
 __do_splice+0x33b/0x370 fs/splice.c:1431
 __do_sys_splice fs/splice.c:1634 [inline]
 __se_sys_splice fs/splice.c:1616 [inline]
 __x64_sys_splice+0x187/0x250 fs/splice.c:1616
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x123/0x790 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f53f6f9e159
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f53f7dfb028 EFLAGS: 00000246 ORIG_RAX: 0000000000000113
RAX: ffffffffffffffda RBX: 00007f53f7225fa0 RCX: 00007f53f6f9e159
RDX: 0000000000000006 RSI: 0000000000000000 RDI: 0000000000000003
RBP: 00007f53f703506b R08: 000000000001000a R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f53f7226038 R14: 00007f53f7225fa0 R15: 00007ffe47d8f3b8
 </TASK>