======================================================
WARNING: possible circular locking dependency detected
5.13.0-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor.0/8502 is trying to acquire lock:
ffffffff8d67b3a8 (loop_ctl_mutex){+.+.}-{3:3}, at: loop_probe+0xe1/0x220 drivers/block/loop.c:2397

but task is already holding lock:
ffffffff8d4e2428 (major_names_lock){+.+.}-{3:3}, at: blk_request_module+0x2f/0x1c0 block/genhd.c:657

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #3 (major_names_lock){+.+.}-{3:3}:
       lock_acquire+0x182/0x4a0 kernel/locking/lockdep.c:5625
       __mutex_lock_common+0x1ad/0x3770 kernel/locking/mutex.c:959
       __mutex_lock kernel/locking/mutex.c:1104 [inline]
       mutex_lock_nested+0x1a/0x20 kernel/locking/mutex.c:1119
       __register_blkdev+0x2c/0x360 block/genhd.c:216
       register_mtd_blktrans+0x94/0x3d0 drivers/mtd/mtd_blkdevs.c:531
       do_one_initcall+0x1a7/0x400 init/main.c:1246
       do_initcall_level+0x14a/0x1f5 init/main.c:1319
       do_initcalls+0x4b/0x8c init/main.c:1335
       kernel_init_freeable+0x3f1/0x57e init/main.c:1557
       kernel_init+0x19/0x2a0 init/main.c:1449
       ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295

-> #2 (mtd_table_mutex){+.+.}-{3:3}:
       lock_acquire+0x182/0x4a0 kernel/locking/lockdep.c:5625
       __mutex_lock_common+0x1ad/0x3770 kernel/locking/mutex.c:959
       __mutex_lock kernel/locking/mutex.c:1104 [inline]
       mutex_lock_nested+0x1a/0x20 kernel/locking/mutex.c:1119
       blktrans_open+0x61/0x430 drivers/mtd/mtd_blkdevs.c:210
       blkdev_get_whole+0x94/0x500 fs/block_dev.c:1251
       blkdev_get_by_dev+0x339/0xdc0 fs/block_dev.c:1415
       blkdev_open+0x132/0x2c0 fs/block_dev.c:1510
       do_dentry_open+0x7cb/0x1010 fs/open.c:826
       do_open fs/namei.c:3361 [inline]
       path_openat+0x28e6/0x39b0 fs/namei.c:3494
       do_filp_open+0x221/0x460 fs/namei.c:3521
       do_sys_openat2+0x124/0x460 fs/open.c:1195
       do_sys_open fs/open.c:1211 [inline]
       __do_sys_open fs/open.c:1219 [inline]
       __se_sys_open fs/open.c:1215 [inline]
       __x64_sys_open+0x221/0x270 fs/open.c:1215
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x44/0xae

-> #1 (&disk->open_mutex){+.+.}-{3:3}:
       lock_acquire+0x182/0x4a0 kernel/locking/lockdep.c:5625
       __mutex_lock_common+0x1ad/0x3770 kernel/locking/mutex.c:959
       __mutex_lock kernel/locking/mutex.c:1104 [inline]
       mutex_lock_nested+0x1a/0x20 kernel/locking/mutex.c:1119
       del_gendisk+0x86/0x610 block/genhd.c:587
       loop_remove drivers/block/loop.c:2344 [inline]
       loop_control_ioctl+0x629/0x740 drivers/block/loop.c:2443
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:1069 [inline]
       __se_sys_ioctl+0xfb/0x170 fs/ioctl.c:1055
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x44/0xae

-> #0 (loop_ctl_mutex){+.+.}-{3:3}:
       check_prev_add kernel/locking/lockdep.c:3051 [inline]
       check_prevs_add+0x4f9/0x5b30 kernel/locking/lockdep.c:3174
       validate_chain kernel/locking/lockdep.c:3789 [inline]
       __lock_acquire+0x4476/0x6100 kernel/locking/lockdep.c:5015
       lock_acquire+0x182/0x4a0 kernel/locking/lockdep.c:5625
       __mutex_lock_common+0x1ad/0x3770 kernel/locking/mutex.c:959
       __mutex_lock kernel/locking/mutex.c:1104 [inline]
       mutex_lock_nested+0x1a/0x20 kernel/locking/mutex.c:1119
       loop_probe+0xe1/0x220 drivers/block/loop.c:2397
       blk_request_module+0x19d/0x1c0 block/genhd.c:660
       blkdev_get_no_open+0x44/0x1f0 fs/block_dev.c:1332
       blkdev_get_by_dev+0x89/0xdc0 fs/block_dev.c:1395
       blkdev_open+0x132/0x2c0 fs/block_dev.c:1510
       do_dentry_open+0x7cb/0x1010 fs/open.c:826
       do_open fs/namei.c:3361 [inline]
       path_openat+0x28e6/0x39b0 fs/namei.c:3494
       do_filp_open+0x221/0x460 fs/namei.c:3521
       do_sys_openat2+0x124/0x460 fs/open.c:1195
       do_sys_open fs/open.c:1211 [inline]
       __do_sys_openat fs/open.c:1227 [inline]
       __se_sys_openat fs/open.c:1222 [inline]
       __x64_sys_openat+0x243/0x290 fs/open.c:1222
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x44/0xae

other info that might help us debug this:

Chain exists of:
  loop_ctl_mutex --> mtd_table_mutex --> major_names_lock

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(major_names_lock);
                               lock(mtd_table_mutex);
                               lock(major_names_lock);
  lock(loop_ctl_mutex);

 *** DEADLOCK ***

1 lock held by syz-executor.0/8502:
 #0: ffffffff8d4e2428 (major_names_lock){+.+.}-{3:3}, at: blk_request_module+0x2f/0x1c0 block/genhd.c:657

stack backtrace:
CPU: 0 PID: 8502 Comm: syz-executor.0 Not tainted 5.13.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:79 [inline]
 dump_stack_lvl+0x1ae/0x29f lib/dump_stack.c:96
 print_circular_bug+0xb17/0xdc0 kernel/locking/lockdep.c:2009
 check_noncircular+0x2cc/0x390 kernel/locking/lockdep.c:2131
 check_prev_add kernel/locking/lockdep.c:3051 [inline]
 check_prevs_add+0x4f9/0x5b30 kernel/locking/lockdep.c:3174
 validate_chain kernel/locking/lockdep.c:3789 [inline]
 __lock_acquire+0x4476/0x6100 kernel/locking/lockdep.c:5015
 lock_acquire+0x182/0x4a0 kernel/locking/lockdep.c:5625
 __mutex_lock_common+0x1ad/0x3770 kernel/locking/mutex.c:959
 __mutex_lock kernel/locking/mutex.c:1104 [inline]
 mutex_lock_nested+0x1a/0x20 kernel/locking/mutex.c:1119
 loop_probe+0xe1/0x220 drivers/block/loop.c:2397
 blk_request_module+0x19d/0x1c0 block/genhd.c:660
 blkdev_get_no_open+0x44/0x1f0 fs/block_dev.c:1332
 blkdev_get_by_dev+0x89/0xdc0 fs/block_dev.c:1395
 blkdev_open+0x132/0x2c0 fs/block_dev.c:1510
 do_dentry_open+0x7cb/0x1010 fs/open.c:826
 do_open fs/namei.c:3361 [inline]
 path_openat+0x28e6/0x39b0 fs/namei.c:3494
 do_filp_open+0x221/0x460 fs/namei.c:3521
 do_sys_openat2+0x124/0x460 fs/open.c:1195
 do_sys_open fs/open.c:1211 [inline]
 __do_sys_openat fs/open.c:1227 [inline]
 __se_sys_openat fs/open.c:1222 [inline]
 __x64_sys_openat+0x243/0x290 fs/open.c:1222
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x4196c4
Code: 84 00 00 00 00 00 44 89 54 24 0c e8 96 f9 ff ff 44 8b 54 24 0c 44 89 e2 48 89 ee 41 89 c0 bf 9c ff ff ff b8 01 01 00 00 0f 05 <48> 3d 00 f0 ff ff 77 34 44 89 c7 89 44 24 0c e8 c8 f9 ff ff 8b 44
RSP: 002b:00007fff97dc71d0 EFLAGS: 00000293 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007fff97dc72e0 RCX: 00000000004196c4
RDX: 0000000000000002 RSI: 00007fff97dc7320 RDI: 00000000ffffff9c
RBP: 00007fff97dc7320 R08: 0000000000000000 R09: 00007fff97dc70e0
R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000002
R13: 000000000003713b R14: 0000000000000000 R15: 00007fff97dc7320