syzbot

======================================================
WARNING: possible circular locking dependency detected
6.10.0-rc4-syzkaller-00148-g50736169ecc8 #0 Not tainted
------------------------------------------------------
syz-executor.3/9553 is trying to acquire lock:
ffff88801f0380a0 (&p->lock){+.+.}-{3:3}, at: seq_read_iter+0xb7/0xd60 fs/seq_file.c:182

but task is already holding lock:
ffff88807e228468 (&pipe->mutex){+.+.}-{3:3}, at: splice_file_to_pipe+0x2e/0x500 fs/splice.c:1292

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #3 (&pipe->mutex){+.+.}-{3:3}:
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5754
       __mutex_lock_common kernel/locking/mutex.c:608 [inline]
       __mutex_lock+0x136/0xd70 kernel/locking/mutex.c:752
       pipe_write+0x1c9/0x1a40 fs/pipe.c:455
       __kernel_write_iter+0x480/0x900 fs/read_write.c:523
       __kernel_write+0x120/0x180 fs/read_write.c:543
       autofs_write fs/autofs/waitq.c:57 [inline]
       autofs_notify_daemon+0x732/0xf80 fs/autofs/waitq.c:164
       autofs_wait+0x10b8/0x1b30 fs/autofs/waitq.c:426
       autofs_mount_wait+0x170/0x330 fs/autofs/root.c:255
       autofs_d_automount+0x555/0x710 fs/autofs/root.c:401
       follow_automount fs/namei.c:1368 [inline]
       __traverse_mounts+0x2bc/0x580 fs/namei.c:1413
       traverse_mounts fs/namei.c:1442 [inline]
       handle_mounts fs/namei.c:1545 [inline]
       step_into+0x5e5/0x1080 fs/namei.c:1842
       lookup_last fs/namei.c:2469 [inline]
       path_lookupat+0x16f/0x450 fs/namei.c:2493
       filename_lookup+0x256/0x610 fs/namei.c:2522
       kern_path+0x35/0x50 fs/namei.c:2630
       lookup_bdev+0xc5/0x290 block/bdev.c:1157
       resume_store+0x1a0/0x710 kernel/power/hibernate.c:1235
       kernfs_fop_write_iter+0x3a3/0x500 fs/kernfs/file.c:334
       new_sync_write fs/read_write.c:497 [inline]
       vfs_write+0xa74/0xc90 fs/read_write.c:590
       ksys_write+0x1a0/0x2c0 fs/read_write.c:643
       do_syscall_x64 arch/x86/entry/common.c:52 [inline]
       do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #2 (&sbi->pipe_mutex){+.+.}-{3:3}:
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5754
       __mutex_lock_common kernel/locking/mutex.c:608 [inline]
       __mutex_lock+0x136/0xd70 kernel/locking/mutex.c:752
       autofs_write fs/autofs/waitq.c:55 [inline]
       autofs_notify_daemon+0x71f/0xf80 fs/autofs/waitq.c:164
       autofs_wait+0x10b8/0x1b30 fs/autofs/waitq.c:426
       autofs_mount_wait+0x170/0x330 fs/autofs/root.c:255
       autofs_d_automount+0x555/0x710 fs/autofs/root.c:401
       follow_automount fs/namei.c:1368 [inline]
       __traverse_mounts+0x2bc/0x580 fs/namei.c:1413
       traverse_mounts fs/namei.c:1442 [inline]
       handle_mounts fs/namei.c:1545 [inline]
       step_into+0x5e5/0x1080 fs/namei.c:1842
       lookup_last fs/namei.c:2469 [inline]
       path_lookupat+0x16f/0x450 fs/namei.c:2493
       filename_lookup+0x256/0x610 fs/namei.c:2522
       kern_path+0x35/0x50 fs/namei.c:2630
       lookup_bdev+0xc5/0x290 block/bdev.c:1157
       resume_store+0x1a0/0x710 kernel/power/hibernate.c:1235
       kernfs_fop_write_iter+0x3a3/0x500 fs/kernfs/file.c:334
       new_sync_write fs/read_write.c:497 [inline]
       vfs_write+0xa74/0xc90 fs/read_write.c:590
       ksys_write+0x1a0/0x2c0 fs/read_write.c:643
       do_syscall_x64 arch/x86/entry/common.c:52 [inline]
       do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #1 (&of->mutex){+.+.}-{3:3}:
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5754
       __mutex_lock_common kernel/locking/mutex.c:608 [inline]
       __mutex_lock+0x136/0xd70 kernel/locking/mutex.c:752
       kernfs_seq_start+0x53/0x3b0 fs/kernfs/file.c:154
       seq_read_iter+0x3d2/0xd60 fs/seq_file.c:225
       copy_splice_read+0x664/0xb60 fs/splice.c:365
       do_splice_read fs/splice.c:985 [inline]
       splice_direct_to_actor+0x4b9/0xc90 fs/splice.c:1089
       do_splice_direct_actor fs/splice.c:1207 [inline]
       do_splice_direct+0x28c/0x3e0 fs/splice.c:1233
       do_sendfile+0x56d/0xe10 fs/read_write.c:1295
       __do_sys_sendfile64 fs/read_write.c:1362 [inline]
       __se_sys_sendfile64+0x17c/0x1e0 fs/read_write.c:1348
       do_syscall_x64 arch/x86/entry/common.c:52 [inline]
       do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #0 (&p->lock){+.+.}-{3:3}:
       check_prev_add kernel/locking/lockdep.c:3134 [inline]
       check_prevs_add kernel/locking/lockdep.c:3253 [inline]
       validate_chain+0x18e0/0x5900 kernel/locking/lockdep.c:3869
       __lock_acquire+0x1346/0x1fd0 kernel/locking/lockdep.c:5137
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5754
       __mutex_lock_common kernel/locking/mutex.c:608 [inline]
       __mutex_lock+0x136/0xd70 kernel/locking/mutex.c:752
       seq_read_iter+0xb7/0xd60 fs/seq_file.c:182
       proc_reg_read_iter+0x1c5/0x290 fs/proc/inode.c:299
       copy_splice_read+0x664/0xb60 fs/splice.c:365
       do_splice_read fs/splice.c:985 [inline]
       splice_file_to_pipe+0x29b/0x500 fs/splice.c:1295
       do_sendfile+0x515/0xe10 fs/read_write.c:1301
       __do_sys_sendfile64 fs/read_write.c:1362 [inline]
       __se_sys_sendfile64+0x17c/0x1e0 fs/read_write.c:1348
       do_syscall_x64 arch/x86/entry/common.c:52 [inline]
       do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

other info that might help us debug this:

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

 Possible unsafe locking scenario:

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

 *** DEADLOCK ***

1 lock held by syz-executor.3/9553:
 #0: ffff88807e228468 (&pipe->mutex){+.+.}-{3:3}, at: splice_file_to_pipe+0x2e/0x500 fs/splice.c:1292

stack backtrace:
CPU: 1 PID: 9553 Comm: syz-executor.3 Not tainted 6.10.0-rc4-syzkaller-00148-g50736169ecc8 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/07/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:114
 check_noncircular+0x36a/0x4a0 kernel/locking/lockdep.c:2187
 check_prev_add kernel/locking/lockdep.c:3134 [inline]
 check_prevs_add kernel/locking/lockdep.c:3253 [inline]
 validate_chain+0x18e0/0x5900 kernel/locking/lockdep.c:3869
 __lock_acquire+0x1346/0x1fd0 kernel/locking/lockdep.c:5137
 lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5754
 __mutex_lock_common kernel/locking/mutex.c:608 [inline]
 __mutex_lock+0x136/0xd70 kernel/locking/mutex.c:752
 seq_read_iter+0xb7/0xd60 fs/seq_file.c:182
 proc_reg_read_iter+0x1c5/0x290 fs/proc/inode.c:299
 copy_splice_read+0x664/0xb60 fs/splice.c:365
 do_splice_read fs/splice.c:985 [inline]
 splice_file_to_pipe+0x29b/0x500 fs/splice.c:1295
 do_sendfile+0x515/0xe10 fs/read_write.c:1301
 __do_sys_sendfile64 fs/read_write.c:1362 [inline]
 __se_sys_sendfile64+0x17c/0x1e0 fs/read_write.c:1348
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f6b42c7cf29
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 20 00 00 90 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 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f6b439ca0c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000028
RAX: ffffffffffffffda RBX: 00007f6b42db3f80 RCX: 00007f6b42c7cf29
RDX: 0000000000000000 RSI: 0000000000000003 RDI: 0000000000000005
RBP: 00007f6b42cec074 R08: 0000000000000000 R09: 0000000000000000
R10: 0000020000023896 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000000b R14: 00007f6b42db3f80 R15: 00007ffef097b618
 </TASK>