syzbot

======================================================
WARNING: possible circular locking dependency detected
6.10.0-rc3-syzkaller-00044-g2ccbdf43d5e7 #0 Not tainted
------------------------------------------------------
syz-executor.4/10867 is trying to acquire lock:
ffff888065ebf418 (&p->lock){+.+.}-{3:3}, at: seq_read_iter+0xb7/0xd60 fs/seq_file.c:182

but task is already holding lock:
ffff88802dccc468 (&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:

-> #5 (&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
       iter_file_splice_write+0x335/0x14e0 fs/splice.c:687
       do_splice_from fs/splice.c:941 [inline]
       do_splice+0xd77/0x1900 fs/splice.c:1354
       __do_splice fs/splice.c:1436 [inline]
       __do_sys_splice fs/splice.c:1652 [inline]
       __se_sys_splice+0x331/0x4a0 fs/splice.c:1634
       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

-> #4 (sb_writers#21){.+.+}-{0:0}:
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5754
       percpu_down_read include/linux/percpu-rwsem.h:51 [inline]
       __sb_start_write include/linux/fs.h:1655 [inline]
       sb_start_write+0x4d/0x1c0 include/linux/fs.h:1791
       mnt_want_write+0x3f/0x90 fs/namespace.c:409
       ovl_want_write fs/overlayfs/util.c:37 [inline]
       ovl_nlink_start+0x1a9/0x390 fs/overlayfs/util.c:1166
       ovl_do_remove+0x1fa/0xd90 fs/overlayfs/dir.c:906
       vfs_rmdir+0x3a3/0x510 fs/namei.c:4214
       do_rmdir+0x3b5/0x580 fs/namei.c:4273
       __do_sys_unlinkat fs/namei.c:4449 [inline]
       __se_sys_unlinkat fs/namei.c:4443 [inline]
       __x64_sys_unlinkat+0xe0/0xf0 fs/namei.c:4443
       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

-> #3 (&ovl_i_lock_key[depth]){+.+.}-{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
       ovl_inode_lock_interruptible fs/overlayfs/overlayfs.h:657 [inline]
       ovl_nlink_start+0xdc/0x390 fs/overlayfs/util.c:1162
       ovl_do_remove+0x1fa/0xd90 fs/overlayfs/dir.c:906
       vfs_rmdir+0x3a3/0x510 fs/namei.c:4214
       do_rmdir+0x3b5/0x580 fs/namei.c:4273
       __do_sys_unlinkat fs/namei.c:4449 [inline]
       __se_sys_unlinkat fs/namei.c:4443 [inline]
       __x64_sys_unlinkat+0xe0/0xf0 fs/namei.c:4443
       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 (&ovl_i_mutex_dir_key[depth]#2){++++}-{3:3}:
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5754
       down_read+0xb1/0xa40 kernel/locking/rwsem.c:1526
       inode_lock_shared include/linux/fs.h:801 [inline]
       lookup_slow+0x45/0x70 fs/namei.c:1708
       walk_component+0x2e1/0x410 fs/namei.c:2004
       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+0x3a1/0x500 fs/kernfs/file.c:334
       new_sync_write fs/read_write.c:497 [inline]
       vfs_write+0xa72/0xc90 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+0x3d0/0xd60 fs/seq_file.c:225
       new_sync_read fs/read_write.c:395 [inline]
       vfs_read+0x9c4/0xbd0 fs/read_write.c:476
       ksys_pread64 fs/read_write.c:671 [inline]
       __do_sys_pread64 fs/read_write.c:681 [inline]
       __se_sys_pread64 fs/read_write.c:678 [inline]
       __x64_sys_pread64+0x1aa/0x230 fs/read_write.c:678
       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
       copy_splice_read+0x662/0xb60 fs/splice.c:365
       do_splice_read fs/splice.c:985 [inline]
       splice_file_to_pipe+0x299/0x500 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 --> sb_writers#21 --> &pipe->mutex

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&pipe->mutex);
                               lock(sb_writers#21);
                               lock(&pipe->mutex);
  lock(&p->lock);

 *** DEADLOCK ***

1 lock held by syz-executor.4/10867:
 #0: ffff88802dccc468 (&pipe->mutex){+.+.}-{3:3}, at: splice_file_to_pipe+0x2e/0x500 fs/splice.c:1292

stack backtrace:
CPU: 1 PID: 10867 Comm: syz-executor.4 Not tainted 6.10.0-rc3-syzkaller-00044-g2ccbdf43d5e7 #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
 copy_splice_read+0x662/0xb60 fs/splice.c:365
 do_splice_read fs/splice.c:985 [inline]
 splice_file_to_pipe+0x299/0x500 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: 0033:0x7fcd37a7cf29
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:00007fcd3871f0c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000028
RAX: ffffffffffffffda RBX: 00007fcd37bb4050 RCX: 00007fcd37a7cf29
RDX: 0000000000000000 RSI: 0000000000000005 RDI: 0000000000000003
RBP: 00007fcd37aec074 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000004 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000006e R14: 00007fcd37bb4050 R15: 00007ffea53ced58
 </TASK>