syzbot

======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.1.8548/29888 is trying to acquire lock:
ffff8880265d7058 (&pipe->mutex){+.+.}-{4:4}, at: anon_pipe_write+0x160/0x1460 fs/pipe.c:458

but task is already holding lock:
ffff8880380c6128 (&sbi->pipe_mutex){+.+.}-{4:4}, at: autofs_write fs/autofs/waitq.c:55 [inline]
ffff8880380c6128 (&sbi->pipe_mutex){+.+.}-{4:4}, at: autofs_notify_daemon+0x70e/0xe20 fs/autofs/waitq.c:164

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 (&sbi->pipe_mutex){+.+.}-{4:4}:
       __mutex_lock_common kernel/locking/rtmutex_api.c:533 [inline]
       mutex_lock_nested+0x5a/0x1d0 kernel/locking/rtmutex_api.c:552
       autofs_write fs/autofs/waitq.c:55 [inline]
       autofs_notify_daemon+0x70e/0xe20 fs/autofs/waitq.c:164
       autofs_wait+0x11f7/0x1900 fs/autofs/waitq.c:426
       autofs_mount_wait+0x16b/0x390 fs/autofs/root.c:255
       autofs_d_automount+0x64f/0x820 fs/autofs/root.c:409
       follow_automount fs/namei.c:1499 [inline]
       __traverse_mounts+0x301/0x5e0 fs/namei.c:1552
       traverse_mounts fs/namei.c:1581 [inline]
       handle_mounts fs/namei.c:1686 [inline]
       step_into_slowpath+0x469/0x7d0 fs/namei.c:2043
       step_into fs/namei.c:2091 [inline]
       walk_component fs/namei.c:2227 [inline]
       lookup_last fs/namei.c:2722 [inline]
       path_lookupat+0x433/0x8c0 fs/namei.c:2746
       filename_lookup+0x212/0x570 fs/namei.c:2775
       kern_path+0x35/0x50 fs/namei.c:2987
       lookup_bdev+0xc0/0x280 block/bdev.c:1222
       resume_store+0x169/0x480 kernel/power/hibernate.c:1306
       kernfs_fop_write_iter+0x3b0/0x540 fs/kernfs/file.c:352
       new_sync_write fs/read_write.c:593 [inline]
       vfs_write+0x5d5/0xb40 fs/read_write.c:686
       ksys_write+0x14b/0x260 fs/read_write.c:738
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0xec/0xf80 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #1 (&of->mutex){+.+.}-{4:4}:
       __mutex_lock_common kernel/locking/rtmutex_api.c:533 [inline]
       mutex_lock_nested+0x5a/0x1d0 kernel/locking/rtmutex_api.c:552
       kernfs_fop_write_iter+0x1df/0x540 fs/kernfs/file.c:343
       iter_file_splice_write+0x977/0x10b0 fs/splice.c:738
       do_splice_from fs/splice.c:938 [inline]
       do_splice+0xc8e/0x1680 fs/splice.c:1351
       __do_splice fs/splice.c:1433 [inline]
       __do_sys_splice fs/splice.c:1636 [inline]
       __se_sys_splice+0x2e1/0x460 fs/splice.c:1618
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0xec/0xf80 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #0 (&pipe->mutex){+.+.}-{4:4}:
       check_prev_add kernel/locking/lockdep.c:3165 [inline]
       check_prevs_add kernel/locking/lockdep.c:3284 [inline]
       validate_chain kernel/locking/lockdep.c:3908 [inline]
       __lock_acquire+0x15a6/0x2cf0 kernel/locking/lockdep.c:5237
       lock_acquire+0x107/0x340 kernel/locking/lockdep.c:5868
       __mutex_lock_common kernel/locking/rtmutex_api.c:533 [inline]
       mutex_lock_nested+0x5a/0x1d0 kernel/locking/rtmutex_api.c:552
       anon_pipe_write+0x160/0x1460 fs/pipe.c:458
       __kernel_write_iter+0x48a/0x920 fs/read_write.c:619
       __kernel_write+0xef/0x150 fs/read_write.c:639
       autofs_write fs/autofs/waitq.c:57 [inline]
       autofs_notify_daemon+0x721/0xe20 fs/autofs/waitq.c:164
       autofs_wait+0x11f7/0x1900 fs/autofs/waitq.c:426
       autofs_mount_wait+0x16b/0x390 fs/autofs/root.c:255
       autofs_d_automount+0x64f/0x820 fs/autofs/root.c:409
       follow_automount fs/namei.c:1499 [inline]
       __traverse_mounts+0x301/0x5e0 fs/namei.c:1552
       traverse_mounts fs/namei.c:1581 [inline]
       handle_mounts fs/namei.c:1686 [inline]
       step_into_slowpath+0x469/0x7d0 fs/namei.c:2043
       step_into fs/namei.c:2091 [inline]
       walk_component fs/namei.c:2227 [inline]
       lookup_last fs/namei.c:2722 [inline]
       path_lookupat+0x433/0x8c0 fs/namei.c:2746
       filename_lookup+0x212/0x570 fs/namei.c:2775
       kern_path+0x35/0x50 fs/namei.c:2987
       lookup_bdev+0xc0/0x280 block/bdev.c:1222
       resume_store+0x169/0x480 kernel/power/hibernate.c:1306
       kernfs_fop_write_iter+0x3b0/0x540 fs/kernfs/file.c:352
       new_sync_write fs/read_write.c:593 [inline]
       vfs_write+0x5d5/0xb40 fs/read_write.c:686
       ksys_write+0x14b/0x260 fs/read_write.c:738
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0xec/0xf80 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

other info that might help us debug this:

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

 Possible unsafe locking scenario:

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

 *** DEADLOCK ***

5 locks held by syz.1.8548/29888:
 #0: ffff8880320ef128 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x253/0x320 fs/file.c:1255
 #1: ffff888032524480 (sb_writers#7){.+.+}-{0:0}, at: file_start_write include/linux/fs.h:2681 [inline]
 #1: ffff888032524480 (sb_writers#7){.+.+}-{0:0}, at: vfs_write+0x217/0xb40 fs/read_write.c:682
 #2: ffff888051317078 (&of->mutex){+.+.}-{4:4}, at: kernfs_fop_write_iter+0x1df/0x540 fs/kernfs/file.c:343
 #3: ffff88801be964b8 (kn->active#60){.+.+}-{0:0}, at: kernfs_get_active_of fs/kernfs/file.c:80 [inline]
 #3: ffff88801be964b8 (kn->active#60){.+.+}-{0:0}, at: kernfs_fop_write_iter+0x232/0x540 fs/kernfs/file.c:344
 #4: ffff8880380c6128 (&sbi->pipe_mutex){+.+.}-{4:4}, at: autofs_write fs/autofs/waitq.c:55 [inline]
 #4: ffff8880380c6128 (&sbi->pipe_mutex){+.+.}-{4:4}, at: autofs_notify_daemon+0x70e/0xe20 fs/autofs/waitq.c:164

stack backtrace:
CPU: 0 UID: 0 PID: 29888 Comm: syz.1.8548 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_circular_bug+0x2e2/0x300 kernel/locking/lockdep.c:2043
 check_noncircular+0x12e/0x150 kernel/locking/lockdep.c:2175
 check_prev_add kernel/locking/lockdep.c:3165 [inline]
 check_prevs_add kernel/locking/lockdep.c:3284 [inline]
 validate_chain kernel/locking/lockdep.c:3908 [inline]
 __lock_acquire+0x15a6/0x2cf0 kernel/locking/lockdep.c:5237
 lock_acquire+0x107/0x340 kernel/locking/lockdep.c:5868
 __mutex_lock_common kernel/locking/rtmutex_api.c:533 [inline]
 mutex_lock_nested+0x5a/0x1d0 kernel/locking/rtmutex_api.c:552
 anon_pipe_write+0x160/0x1460 fs/pipe.c:458
 __kernel_write_iter+0x48a/0x920 fs/read_write.c:619
 __kernel_write+0xef/0x150 fs/read_write.c:639
 autofs_write fs/autofs/waitq.c:57 [inline]
 autofs_notify_daemon+0x721/0xe20 fs/autofs/waitq.c:164
 autofs_wait+0x11f7/0x1900 fs/autofs/waitq.c:426
 autofs_mount_wait+0x16b/0x390 fs/autofs/root.c:255
 autofs_d_automount+0x64f/0x820 fs/autofs/root.c:409
 follow_automount fs/namei.c:1499 [inline]
 __traverse_mounts+0x301/0x5e0 fs/namei.c:1552
 traverse_mounts fs/namei.c:1581 [inline]
 handle_mounts fs/namei.c:1686 [inline]
 step_into_slowpath+0x469/0x7d0 fs/namei.c:2043
 step_into fs/namei.c:2091 [inline]
 walk_component fs/namei.c:2227 [inline]
 lookup_last fs/namei.c:2722 [inline]
 path_lookupat+0x433/0x8c0 fs/namei.c:2746
 filename_lookup+0x212/0x570 fs/namei.c:2775
 kern_path+0x35/0x50 fs/namei.c:2987
 lookup_bdev+0xc0/0x280 block/bdev.c:1222
 resume_store+0x169/0x480 kernel/power/hibernate.c:1306
 kernfs_fop_write_iter+0x3b0/0x540 fs/kernfs/file.c:352
 new_sync_write fs/read_write.c:593 [inline]
 vfs_write+0x5d5/0xb40 fs/read_write.c:686
 ksys_write+0x14b/0x260 fs/read_write.c:738
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xec/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f1c5088f749
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:00007f1c4eaf6038 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f1c50ae5fa0 RCX: 00007f1c5088f749
RDX: 0000000000000012 RSI: 0000200000000040 RDI: 0000000000000009
RBP: 00007f1c50913f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f1c50ae6038 R14: 00007f1c50ae5fa0 R15: 00007ffda9f97068
 </TASK>
PM: Image not found (code -22)