======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Tainted: G             L     
------------------------------------------------------
syz.5.2058/14687 is trying to acquire lock:
ffff888056162c60 (&pipe->mutex){+.+.}-{4:4}, at: iter_file_splice_write+0x20a/0x1240 fs/splice.c:682

but task is already holding lock:
ffff88802bbb6450 (sb_writers#5){.+.+}-{0:0}, at: do_splice+0xe87/0x1970 fs/splice.c:1348

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #4 (sb_writers#5){.+.+}-{0:0}:
       percpu_down_read_internal include/linux/percpu-rwsem.h:53 [inline]
       percpu_down_read_freezable include/linux/percpu-rwsem.h:83 [inline]
       __sb_start_write include/linux/fs/super.h:19 [inline]
       sb_start_write+0x4d/0x1c0 include/linux/fs/super.h:125
       mnt_want_write+0x41/0x90 fs/namespace.c:494
       ovl_create_object+0x108/0x3b0 fs/overlayfs/dir.c:706
       lookup_open fs/namei.c:4508 [inline]
       open_last_lookups fs/namei.c:4608 [inline]
       path_openat+0x133a/0x3830 fs/namei.c:4860
       do_file_open+0x23e/0x4a0 fs/namei.c:4892
       do_sys_openat2+0x115/0x200 fs/open.c:1368
       do_sys_open fs/open.c:1374 [inline]
       __do_sys_openat fs/open.c:1390 [inline]
       __se_sys_openat fs/open.c:1385 [inline]
       __x64_sys_openat+0x138/0x170 fs/open.c:1385
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #3 (&ovl_i_mutex_dir_key[depth]){++++}-{4:4}:
       down_read+0x4a/0x330 kernel/locking/rwsem.c:1574
       inode_lock_shared include/linux/fs.h:1039 [inline]
       lookup_slow+0x46/0x70 fs/namei.c:1935
       walk_component fs/namei.c:2282 [inline]
       lookup_last fs/namei.c:2789 [inline]
       path_lookupat+0x3f5/0x8c0 fs/namei.c:2813
       filename_lookup+0x265/0x5d0 fs/namei.c:2842
       kern_path+0x3d/0x150 fs/namei.c:3036
       lookup_bdev+0xc8/0x290 block/bdev.c:1208
       resume_store+0x16f/0x4f0 kernel/power/hibernate.c:1278
       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:63 [inline]
       do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #2 (&of->mutex){+.+.}-{4:4}:
       __mutex_lock_common kernel/locking/mutex.c:646 [inline]
       __mutex_lock+0x19d/0x1550 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:1084
       do_splice_direct_actor fs/splice.c:1202 [inline]
       do_splice_direct+0x195/0x290 fs/splice.c:1228
       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:63 [inline]
       do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #1 (&p->lock){+.+.}-{4:4}:
       __mutex_lock_common kernel/locking/mutex.c:646 [inline]
       __mutex_lock+0x19d/0x1550 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+0x444/0x6b0 fs/splice.c:1290
       do_splice+0x11c2/0x1970 fs/splice.c:1374
       __do_splice fs/splice.c:1431 [inline]
       __do_sys_splice fs/splice.c:1634 [inline]
       __se_sys_splice+0x353/0x490 fs/splice.c:1616
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0x174/0x580 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+0x1520/0x2cf0 kernel/locking/lockdep.c:5237
       lock_acquire+0x106/0x350 kernel/locking/lockdep.c:5868
       __mutex_lock_common kernel/locking/mutex.c:646 [inline]
       __mutex_lock+0x19d/0x1550 kernel/locking/mutex.c:821
       iter_file_splice_write+0x20a/0x1240 fs/splice.c:682
       do_splice_from fs/splice.c:936 [inline]
       do_splice+0xf14/0x1970 fs/splice.c:1349
       __do_splice fs/splice.c:1431 [inline]
       __do_sys_splice fs/splice.c:1634 [inline]
       __se_sys_splice+0x353/0x490 fs/splice.c:1616
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0x174/0x580 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 --> &ovl_i_mutex_dir_key[depth] --> sb_writers#5

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  rlock(sb_writers#5);
                               lock(&ovl_i_mutex_dir_key[depth]);
                               lock(sb_writers#5);
  lock(&pipe->mutex);

 *** DEADLOCK ***

1 lock held by syz.5.2058/14687:
 #0: ffff88802bbb6450 (sb_writers#5){.+.+}-{0:0}, at: do_splice+0xe87/0x1970 fs/splice.c:1348

stack backtrace:
CPU: 0 UID: 0 PID: 14687 Comm: syz.5.2058 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_circular_bug+0x2e1/0x300 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+0x1520/0x2cf0 kernel/locking/lockdep.c:5237
 lock_acquire+0x106/0x350 kernel/locking/lockdep.c:5868
 __mutex_lock_common kernel/locking/mutex.c:646 [inline]
 __mutex_lock+0x19d/0x1550 kernel/locking/mutex.c:821
 iter_file_splice_write+0x20a/0x1240 fs/splice.c:682
 do_splice_from fs/splice.c:936 [inline]
 do_splice+0xf14/0x1970 fs/splice.c:1349
 __do_splice fs/splice.c:1431 [inline]
 __do_sys_splice fs/splice.c:1634 [inline]
 __se_sys_splice+0x353/0x490 fs/splice.c:1616
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f2c6cf9e0d9
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:00007f2c6de4b028 EFLAGS: 00000246 ORIG_RAX: 0000000000000113
RAX: ffffffffffffffda RBX: 00007f2c6d226090 RCX: 00007f2c6cf9e0d9
RDX: 000000000000000d RSI: 0000000000000000 RDI: 000000000000000a
RBP: 00007f2c6d035024 R08: 00000000088000cc R09: 1000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f2c6d226128 R14: 00007f2c6d226090 R15: 00007ffef673c808
 </TASK>