======================================================
WARNING: possible circular locking dependency detected
5.14.0-rc7-next-20210824-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor.2/8197 is trying to acquire lock:
ffff88803b4e4230 (&mddev->open_mutex){+.+.}-{3:3}, at: md_open+0xfd/0x2e0 drivers/md/md.c:7815

but task is already holding lock:
ffff88807b007118 (&disk->open_mutex){+.+.}-{3:3}, at: blkdev_get_by_dev.part.0+0x9b/0xb60 fs/block_dev.c:1227

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&disk->open_mutex){+.+.}-{3:3}:
       __mutex_lock_common kernel/locking/mutex.c:596 [inline]
       __mutex_lock+0x131/0x12f0 kernel/locking/mutex.c:729
       bd_register_pending_holders+0x2c/0x470 block/holder.c:160
       device_add_disk+0x75e/0xfd0 block/genhd.c:505
       add_disk include/linux/genhd.h:221 [inline]
       md_alloc+0x91d/0x1150 drivers/md/md.c:5707
       md_probe+0x69/0x70 drivers/md/md.c:5738
       blk_request_module+0x111/0x1d0 block/genhd.c:667
       blkdev_get_no_open+0x178/0x1e0 fs/block_dev.c:1150
       blkdev_get_by_dev.part.0+0x22/0xb60 fs/block_dev.c:1214
       blkdev_get_by_dev fs/block_dev.c:1323 [inline]
       blkdev_open+0x295/0x300 fs/block_dev.c:1329
       do_dentry_open+0x4c8/0x11d0 fs/open.c:822
       do_open fs/namei.c:3426 [inline]
       path_openat+0x1c9a/0x2740 fs/namei.c:3559
       do_filp_open+0x1aa/0x400 fs/namei.c:3586
       do_sys_openat2+0x16d/0x4d0 fs/open.c:1200
       do_sys_open fs/open.c:1216 [inline]
       __do_sys_openat fs/open.c:1232 [inline]
       __se_sys_openat fs/open.c:1227 [inline]
       __x64_sys_openat+0x13f/0x1f0 fs/open.c:1227
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x44/0xae

-> #0 (&mddev->open_mutex){+.+.}-{3:3}:
       check_prev_add kernel/locking/lockdep.c:3051 [inline]
       check_prevs_add kernel/locking/lockdep.c:3174 [inline]
       validate_chain kernel/locking/lockdep.c:3789 [inline]
       __lock_acquire+0x2a07/0x54a0 kernel/locking/lockdep.c:5015
       lock_acquire kernel/locking/lockdep.c:5625 [inline]
       lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5590
       __mutex_lock_common kernel/locking/mutex.c:596 [inline]
       __mutex_lock+0x131/0x12f0 kernel/locking/mutex.c:729
       md_open+0xfd/0x2e0 drivers/md/md.c:7815
       blkdev_get_whole+0x99/0x2a0 fs/block_dev.c:1079
       blkdev_get_by_dev.part.0+0x354/0xb60 fs/block_dev.c:1234
       blkdev_get_by_dev fs/block_dev.c:1323 [inline]
       blkdev_open+0x295/0x300 fs/block_dev.c:1329
       do_dentry_open+0x4c8/0x11d0 fs/open.c:822
       do_open fs/namei.c:3426 [inline]
       path_openat+0x1c9a/0x2740 fs/namei.c:3559
       do_filp_open+0x1aa/0x400 fs/namei.c:3586
       do_sys_openat2+0x16d/0x4d0 fs/open.c:1200
       do_sys_open fs/open.c:1216 [inline]
       __do_sys_openat fs/open.c:1232 [inline]
       __se_sys_openat fs/open.c:1227 [inline]
       __x64_sys_openat+0x13f/0x1f0 fs/open.c:1227
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x44/0xae

other info that might help us debug this:

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&disk->open_mutex);
                               lock(&mddev->open_mutex);
                               lock(&disk->open_mutex);
  lock(&mddev->open_mutex);

 *** DEADLOCK ***

1 lock held by syz-executor.2/8197:
 #0: ffff88807b007118 (&disk->open_mutex){+.+.}-{3:3}, at: blkdev_get_by_dev.part.0+0x9b/0xb60 fs/block_dev.c:1227

stack backtrace:
CPU: 0 PID: 8197 Comm: syz-executor.2 Not tainted 5.14.0-rc7-next-20210824-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
 check_noncircular+0x25f/0x2e0 kernel/locking/lockdep.c:2131
 check_prev_add kernel/locking/lockdep.c:3051 [inline]
 check_prevs_add kernel/locking/lockdep.c:3174 [inline]
 validate_chain kernel/locking/lockdep.c:3789 [inline]
 __lock_acquire+0x2a07/0x54a0 kernel/locking/lockdep.c:5015
 lock_acquire kernel/locking/lockdep.c:5625 [inline]
 lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5590
 __mutex_lock_common kernel/locking/mutex.c:596 [inline]
 __mutex_lock+0x131/0x12f0 kernel/locking/mutex.c:729
 md_open+0xfd/0x2e0 drivers/md/md.c:7815
 blkdev_get_whole+0x99/0x2a0 fs/block_dev.c:1079
 blkdev_get_by_dev.part.0+0x354/0xb60 fs/block_dev.c:1234
 blkdev_get_by_dev fs/block_dev.c:1323 [inline]
 blkdev_open+0x295/0x300 fs/block_dev.c:1329
 do_dentry_open+0x4c8/0x11d0 fs/open.c:822
 do_open fs/namei.c:3426 [inline]
 path_openat+0x1c9a/0x2740 fs/namei.c:3559
 do_filp_open+0x1aa/0x400 fs/namei.c:3586
 do_sys_openat2+0x16d/0x4d0 fs/open.c:1200
 do_sys_open fs/open.c:1216 [inline]
 __do_sys_openat fs/open.c:1232 [inline]
 __se_sys_openat fs/open.c:1227 [inline]
 __x64_sys_openat+0x13f/0x1f0 fs/open.c:1227
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x4665e9
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 bc ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f0e05717188 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 000000000056c038 RCX: 00000000004665e9
RDX: 0000000000000000 RSI: 00000000200020c0 RDI: ffffffffffffff9c
RBP: 00000000004bfcc4 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056c038
R13: 00007ffde146e33f R14: 00007f0e05717300 R15: 0000000000022000