autofs4:pid:12899:autofs_wait: new wait id = 0x00000008, name = 0x0000000004000921, nfy=1
autofs4:pid:12899:autofs_notify_daemon: wait id = 0x00000008, name = 0x0000000004000921, type=3
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.4.1343/12899 is trying to acquire lock:
ffff888079a45938 (&sbi->pipe_mutex){+.+.}-{4:4}, at: autofs_write fs/autofs/waitq.c:68 [inline]
ffff888079a45938 (&sbi->pipe_mutex){+.+.}-{4:4}, at: autofs_notify_daemon+0x75d/0xf10 fs/autofs/waitq.c:177

but task is already holding lock:
ffff88802c6d9080 (&of->mutex){+.+.}-{4:4}, at: kernfs_fop_write_iter+0x1d8/0x540 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}:
       __mutex_lock_common kernel/locking/mutex.c:646 [inline]
       __mutex_lock+0x197/0x15a0 kernel/locking/mutex.c:821
       kernfs_seq_start+0x5d/0x420 fs/kernfs/file.c:165
       seq_read_iter+0x37e/0xca0 fs/seq_file.c:226
       copy_splice_read+0x5ff/0xaa0 fs/splice.c:362
       do_splice_read fs/splice.c:980 [inline]
       splice_direct_to_actor+0x48b/0xcb0 fs/splice.c:1077
       do_splice_direct_actor fs/splice.c:1230 [inline]
       do_splice_direct+0x195/0x290 fs/splice.c:1256
       do_sendfile+0x52e/0x7c0 fs/read_write.c:1371
       __do_sys_sendfile64 fs/read_write.c:1432 [inline]
       __se_sys_sendfile64+0x144/0x1a0 fs/read_write.c:1418
       do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
       do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #2 (&p->lock){+.+.}-{4:4}:
       __mutex_lock_common kernel/locking/mutex.c:646 [inline]
       __mutex_lock+0x197/0x15a0 kernel/locking/mutex.c:821
       seq_read_iter+0xa4/0xca0 fs/seq_file.c:183
       proc_reg_read_iter+0x1b7/0x280 fs/proc/inode.c:299
       copy_splice_read+0x5ff/0xaa0 fs/splice.c:362
       do_splice_read fs/splice.c:980 [inline]
       splice_file_to_pipe+0x4ab/0x720 fs/splice.c:1318
       do_splice+0x124a/0x19f0 fs/splice.c:1402
       __do_splice fs/splice.c:1459 [inline]
       __do_sys_splice fs/splice.c:1662 [inline]
       __se_sys_splice+0x353/0x490 fs/splice.c:1644
       do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
       do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #1 (&pipe->mutex){+.+.}-{4:4}:
       __mutex_lock_common kernel/locking/mutex.c:646 [inline]
       __mutex_lock+0x197/0x15a0 kernel/locking/mutex.c:821
       anon_pipe_prefill_and_lock fs/pipe.c:165 [inline]
       anon_pipe_write+0x28f/0x1a90 fs/pipe.c:534
       __kernel_write_iter+0x44a/0x8f0 fs/read_write.c:621
       __kernel_write+0x106/0x170 fs/read_write.c:641
       autofs_write fs/autofs/waitq.c:70 [inline]
       autofs_notify_daemon+0x770/0xf10 fs/autofs/waitq.c:177
       autofs_wait+0x11aa/0x18a0 fs/autofs/waitq.c:439
       autofs_mount_wait+0x16b/0x390 fs/autofs/root.c:256
       autofs_d_automount+0x64e/0x810 fs/autofs/root.c:410
       follow_automount fs/namei.c:1565 [inline]
       __traverse_mounts+0x2fe/0x5d0 fs/namei.c:1618
       traverse_mounts fs/namei.c:1647 [inline]
       handle_mounts fs/namei.c:1749 [inline]
       step_into_slowpath+0x4ba/0x820 fs/namei.c:2104
       step_into fs/namei.c:2152 [inline]
       open_last_lookups fs/namei.c:4781 [inline]
       path_openat+0xa97/0x20f0 fs/namei.c:5007
       do_file_open+0x23e/0x4a0 fs/namei.c:5039
       do_sys_openat2+0x115/0x200 fs/open.c:1442
       do_sys_open fs/open.c:1448 [inline]
       __do_sys_openat fs/open.c:1464 [inline]
       __se_sys_openat fs/open.c:1459 [inline]
       __x64_sys_openat+0x138/0x170 fs/open.c:1459
       do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
       do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #0 (&sbi->pipe_mutex){+.+.}-{4:4}:
       check_prev_add kernel/locking/lockdep.c:3209 [inline]
       check_prevs_add kernel/locking/lockdep.c:3328 [inline]
       validate_chain kernel/locking/lockdep.c:3952 [inline]
       __lock_acquire+0x164c/0x2de0 kernel/locking/lockdep.c:5288
       lock_acquire+0x115/0x350 kernel/locking/lockdep.c:5942
       __mutex_lock_common kernel/locking/mutex.c:646 [inline]
       __mutex_lock+0x197/0x15a0 kernel/locking/mutex.c:821
       autofs_write fs/autofs/waitq.c:68 [inline]
       autofs_notify_daemon+0x75d/0xf10 fs/autofs/waitq.c:177
       autofs_wait+0x11aa/0x18a0 fs/autofs/waitq.c:439
       autofs_mount_wait+0x16b/0x390 fs/autofs/root.c:256
       autofs_d_automount+0x64e/0x810 fs/autofs/root.c:410
       follow_automount fs/namei.c:1565 [inline]
       __traverse_mounts+0x2fe/0x5d0 fs/namei.c:1618
       traverse_mounts fs/namei.c:1647 [inline]
       handle_mounts fs/namei.c:1749 [inline]
       step_into_slowpath+0x4ba/0x820 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+0x433/0x8c0 fs/namei.c:2813
       filename_lookup+0x265/0x5d0 fs/namei.c:2842
       kern_path+0x3d/0x150 fs/namei.c:3036
       lookup_bdev+0xc8/0x2b0 block/bdev.c:1268
       resume_store+0x181/0x500 kernel/power/hibernate.c:1286
       kernfs_fop_write_iter+0x3a4/0x540 fs/kernfs/file.c:345
       new_sync_write fs/read_write.c:595 [inline]
       vfs_write+0x612/0xba0 fs/read_write.c:687
       ksys_write+0x150/0x270 fs/read_write.c:739
       do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
       do_syscall_64+0x166/0x520 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.4.1343/12899: 4, last CPU#1:
 #0: ffff88807f9f9b30 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x118/0x160 fs/file.c:1409
 #1: ffff888032c4c460 (sb_writers#7){.+.+}-{0:0}, at: file_start_write include/linux/fs.h:2760 [inline]
 #1: ffff888032c4c460 (sb_writers#7){.+.+}-{0:0}, at: vfs_write+0x22b/0xba0 fs/read_write.c:683
 #2: ffff88802c6d9080 (&of->mutex){+.+.}-{4:4}, at: kernfs_fop_write_iter+0x1d8/0x540 fs/kernfs/file.c:336
 #3: ffff88801fef7a58 (kn->active#61){.+.+}-{0:0}, at: kernfs_get_active_of fs/kernfs/file.c:73 [inline]
 #3: ffff88801fef7a58 (kn->active#61){.+.+}-{0:0}, at: kernfs_fop_write_iter+0x22b/0x540 fs/kernfs/file.c:337

stack backtrace:
CPU: 1 UID: 0 PID: 12899 Comm: syz.4.1343 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_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_circular_bug+0x2e2/0x300 kernel/locking/lockdep.c:2087
 check_noncircular+0x12f/0x150 kernel/locking/lockdep.c:2219
 check_prev_add kernel/locking/lockdep.c:3209 [inline]
 check_prevs_add kernel/locking/lockdep.c:3328 [inline]
 validate_chain kernel/locking/lockdep.c:3952 [inline]
 __lock_acquire+0x164c/0x2de0 kernel/locking/lockdep.c:5288
 lock_acquire+0x115/0x350 kernel/locking/lockdep.c:5942
 __mutex_lock_common kernel/locking/mutex.c:646 [inline]
 __mutex_lock+0x197/0x15a0 kernel/locking/mutex.c:821
 autofs_write fs/autofs/waitq.c:68 [inline]
 autofs_notify_daemon+0x75d/0xf10 fs/autofs/waitq.c:177
 autofs_wait+0x11aa/0x18a0 fs/autofs/waitq.c:439
 autofs_mount_wait+0x16b/0x390 fs/autofs/root.c:256
 autofs_d_automount+0x64e/0x810 fs/autofs/root.c:410
 follow_automount fs/namei.c:1565 [inline]
 __traverse_mounts+0x2fe/0x5d0 fs/namei.c:1618
 traverse_mounts fs/namei.c:1647 [inline]
 handle_mounts fs/namei.c:1749 [inline]
 step_into_slowpath+0x4ba/0x820 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+0x433/0x8c0 fs/namei.c:2813
 filename_lookup+0x265/0x5d0 fs/namei.c:2842
 kern_path+0x3d/0x150 fs/namei.c:3036
 lookup_bdev+0xc8/0x2b0 block/bdev.c:1268
 resume_store+0x181/0x500 kernel/power/hibernate.c:1286
 kernfs_fop_write_iter+0x3a4/0x540 fs/kernfs/file.c:345
 new_sync_write fs/read_write.c:595 [inline]
 vfs_write+0x612/0xba0 fs/read_write.c:687
 ksys_write+0x150/0x270 fs/read_write.c:739
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f9f8319f559
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:00007f9f813f6028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f9f83426180 RCX: 00007f9f8319f559
RDX: 0000000000000012 RSI: 00002000000003c0 RDI: 0000000000000009
RBP: 00007f9f83236b20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f9f83426218 R14: 00007f9f83426180 R15: 00007fff2e4a2a08
 </TASK>
autofs4:pid:12899:autofs_catatonic_mode_locked: entering catatonic mode
autofs4:pid:12899:autofs_mount_wait: mount wait done status=-2
autofs4:pid:12899:autofs_dentry_release: releasing ffff88807a3756c0
PM: hibernation: Configured hibernation resume from disk to 9453601
PM: hibernation: Hibernation image partition 9:16417 present
PM: hibernation: Looking for hibernation image.
PM: Image not found (code -6)
PM: hibernation: Hibernation image not present or could not be loaded.
kcov: kcov_task_exit: t = ffff888033c5ddc0, kcov->t = ffff888033c5ddc0
autofs4:pid:12899:autofs_kill_sb: shutting down
autofs4:pid:12899:autofs_dentry_release: releasing ffff88806786ab60