======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.9.1535/12862 is trying to acquire lock:
ffff888058d63138 (&sbi->pipe_mutex){+.+.}-{4:4}, at: autofs_write fs/autofs/waitq.c:55 [inline]
ffff888058d63138 (&sbi->pipe_mutex){+.+.}-{4:4}, at: autofs_notify_daemon+0x4f8/0xd90 fs/autofs/waitq.c:164

but task is already holding lock:
ffff888079687880 (&of->mutex){+.+.}-{4:4}, at: kernfs_fop_write_iter+0x2c2/0x5f0 fs/kernfs/file.c:336

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #3 (&of->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
       kernfs_seq_start+0x4f/0x2a0 fs/kernfs/file.c:165
       seq_read_iter+0x2c1/0x1270 fs/seq_file.c:226
       kernfs_fop_read_iter+0x46c/0x610 fs/kernfs/file.c:290
       copy_splice_read+0x4ba/0xbb0 fs/splice.c:362
       do_splice_read fs/splice.c:980 [inline]
       do_splice_read+0x285/0x370 fs/splice.c:954
       splice_direct_to_actor+0x2a1/0xa30 fs/splice.c:1084
       do_splice_direct_actor fs/splice.c:1202 [inline]
       do_splice_direct+0x174/0x240 fs/splice.c:1228
       do_sendfile+0xadc/0xe20 fs/read_write.c:1371
       __do_sys_sendfile64 fs/read_write.c:1432 [inline]
       __se_sys_sendfile64 fs/read_write.c:1418 [inline]
       __x64_sys_sendfile64+0x1d8/0x220 fs/read_write.c:1418
       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

-> #2 (&p->lock){+.+.}-{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
       seq_read_iter+0xe1/0x1270 fs/seq_file.c:183
       proc_reg_read_iter+0x220/0x310 fs/proc/inode.c:299
       copy_splice_read+0x4ba/0xbb0 fs/splice.c:362
       do_splice_read fs/splice.c:980 [inline]
       do_splice_read+0x285/0x370 fs/splice.c:954
       splice_file_to_pipe+0x82/0x120 fs/splice.c:1290
       do_sendfile+0x366/0xe20 fs/read_write.c:1377
       __do_sys_sendfile64 fs/read_write.c:1432 [inline]
       __se_sys_sendfile64 fs/read_write.c:1418 [inline]
       __x64_sys_sendfile64+0x1d8/0x220 fs/read_write.c:1418
       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 (&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+0x3fb/0x580 fs/pipe.c:153
       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]
       open_last_lookups fs/namei.c:4780 [inline]
       path_openat+0xfab/0x2440 fs/namei.c:4997
       do_file_open+0x20e/0x430 fs/namei.c:5029
       do_sys_openat2+0x10f/0x1e0 fs/open.c:1417
       do_sys_open fs/open.c:1423 [inline]
       __do_sys_openat fs/open.c:1439 [inline]
       __se_sys_openat fs/open.c:1434 [inline]
       __x64_sys_openat+0x12d/0x210 fs/open.c:1434
       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 (&sbi->pipe_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
       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

other info that might help us debug this:

Chain exists of:
  &sbi->pipe_mutex --> &p->lock --> &of->mutex

 Possible unsafe locking scenario:

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

 *** DEADLOCK ***

locks held by syz.9.1535/12862: 4, last CPU#1:
 #0: ffff88807dfb0ef0 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x2aa/0x380 fs/file.c:1259
 #1: ffff88803839e460 (sb_writers#8){.+.+}-{0:0}, at: ksys_write+0x12a/0x250 fs/read_write.c:739
 #2: ffff888079687880 (&of->mutex){+.+.}-{4:4}, at: kernfs_fop_write_iter+0x2c2/0x5f0 fs/kernfs/file.c:336
 #3: ffff8880206ef5a8 (kn->active#68){.+.+}-{0:0}, at: kernfs_get_active_of fs/kernfs/file.c:73 [inline]
 #3: ffff8880206ef5a8 (kn->active#68){.+.+}-{0:0}, at: kernfs_fop_write_iter+0x332/0x5f0 fs/kernfs/file.c:337

stack backtrace:
CPU: 1 UID: 0 PID: 12862 Comm: syz.9.1535 Not tainted syzkaller #0 PREEMPT(full) 
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
 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
RIP: 0033:0x7f2040d9e159
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:00007f2041bdd028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f2041025fa0 RCX: 00007f2040d9e159
RDX: 0000000000000012 RSI: 0000200000000040 RDI: 0000000000000009
RBP: 00007f2040e3506b R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f2041026038 R14: 00007f2041025fa0 R15: 00007ffdcf4877e8
 </TASK>
PM: Image not found (code -6)