====================================================== WARNING: possible circular locking dependency detected 5.12.0-syzkaller #0 Not tainted ------------------------------------------------------ syz-executor702/8370 is trying to acquire lock: ffffffff8d465ae8 (brd_devices_mutex){+.+.}-{3:3}, at: brd_probe+0x3a/0x1f0 drivers/block/brd.c:441 but task is already holding lock: ffffffff8d2d3f08 (major_names_lock){+.+.}-{3:3}, at: blk_request_module+0x2f/0x1c0 block/genhd.c:689 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #3 (major_names_lock){+.+.}-{3:3}: lock_acquire+0x17f/0x720 kernel/locking/lockdep.c:5512 __mutex_lock_common+0x1bd/0x2e50 kernel/locking/mutex.c:949 __mutex_lock kernel/locking/mutex.c:1096 [inline] mutex_lock_nested+0x1a/0x20 kernel/locking/mutex.c:1111 __register_blkdev+0x2c/0x360 block/genhd.c:225 register_mtd_blktrans+0x94/0x3d0 drivers/mtd/mtd_blkdevs.c:534 do_one_initcall+0x1a7/0x400 init/main.c:1249 do_initcall_level+0x14a/0x1f5 init/main.c:1322 do_initcalls+0x4b/0x8c init/main.c:1338 kernel_init_freeable+0x3a3/0x505 init/main.c:1560 kernel_init+0xd/0x290 init/main.c:1447 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294 -> #2 (mtd_table_mutex){+.+.}-{3:3}: lock_acquire+0x17f/0x720 kernel/locking/lockdep.c:5512 __mutex_lock_common+0x1bd/0x2e50 kernel/locking/mutex.c:949 __mutex_lock kernel/locking/mutex.c:1096 [inline] mutex_lock_nested+0x1a/0x20 kernel/locking/mutex.c:1111 blktrans_open+0x61/0x430 drivers/mtd/mtd_blkdevs.c:212 __blkdev_get+0x251/0xa60 fs/block_dev.c:1305 blkdev_get_by_dev+0xf9/0x640 fs/block_dev.c:1453 blkdev_open+0x132/0x2c0 fs/block_dev.c:1548 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:1187 do_sys_open fs/open.c:1203 [inline] __do_sys_open fs/open.c:1211 [inline] __se_sys_open fs/open.c:1207 [inline] __x64_sys_open+0x221/0x270 fs/open.c:1207 do_syscall_64+0x3f/0xb0 arch/x86/entry/common.c:47 entry_SYSCALL_64_after_hwframe+0x44/0xae -> #1 (&bdev->bd_mutex){+.+.}-{3:3}: lock_acquire+0x17f/0x720 kernel/locking/lockdep.c:5512 __mutex_lock_common+0x1bd/0x2e50 kernel/locking/mutex.c:949 __mutex_lock kernel/locking/mutex.c:1096 [inline] mutex_lock_nested+0x1a/0x20 kernel/locking/mutex.c:1111 blkdev_get_by_dev+0xee/0x640 fs/block_dev.c:1452 disk_scan_partitions block/genhd.c:427 [inline] register_disk block/genhd.c:474 [inline] __device_add_disk+0xb0b/0x10d0 block/genhd.c:555 add_disk include/linux/genhd.h:212 [inline] brd_init+0x2d8/0x49e drivers/block/brd.c:527 do_one_initcall+0x1a7/0x400 init/main.c:1249 do_initcall_level+0x14a/0x1f5 init/main.c:1322 do_initcalls+0x4b/0x8c init/main.c:1338 kernel_init_freeable+0x3a3/0x505 init/main.c:1560 kernel_init+0xd/0x290 init/main.c:1447 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294 -> #0 (brd_devices_mutex){+.+.}-{3:3}: check_prev_add kernel/locking/lockdep.c:2938 [inline] check_prevs_add+0x4d6/0x5a90 kernel/locking/lockdep.c:3061 validate_chain kernel/locking/lockdep.c:3676 [inline] __lock_acquire+0x4307/0x6040 kernel/locking/lockdep.c:4902 lock_acquire+0x17f/0x720 kernel/locking/lockdep.c:5512 __mutex_lock_common+0x1bd/0x2e50 kernel/locking/mutex.c:949 __mutex_lock kernel/locking/mutex.c:1096 [inline] mutex_lock_nested+0x1a/0x20 kernel/locking/mutex.c:1111 brd_probe+0x3a/0x1f0 drivers/block/brd.c:441 blk_request_module+0x19d/0x1c0 block/genhd.c:692 blkdev_get_no_open+0x5c/0x220 fs/block_dev.c:1371 blkdev_get_by_dev+0x82/0x640 fs/block_dev.c:1439 blkdev_open+0x132/0x2c0 fs/block_dev.c:1548 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:1187 do_sys_open fs/open.c:1203 [inline] __do_sys_openat fs/open.c:1219 [inline] __se_sys_openat fs/open.c:1214 [inline] __x64_sys_openat+0x243/0x290 fs/open.c:1214 do_syscall_64+0x3f/0xb0 arch/x86/entry/common.c:47 entry_SYSCALL_64_after_hwframe+0x44/0xae other info that might help us debug this: Chain exists of: brd_devices_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(brd_devices_mutex); *** DEADLOCK *** 1 lock held by syz-executor702/8370: #0: ffffffff8d2d3f08 (major_names_lock){+.+.}-{3:3}, at: blk_request_module+0x2f/0x1c0 block/genhd.c:689 stack backtrace: CPU: 1 PID: 8370 Comm: syz-executor702 Not tainted 5.12.0-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+0x202/0x31e lib/dump_stack.c:120 print_circular_bug+0xb17/0xdc0 kernel/locking/lockdep.c:2007 check_noncircular+0x2cc/0x390 kernel/locking/lockdep.c:2129 check_prev_add kernel/locking/lockdep.c:2938 [inline] check_prevs_add+0x4d6/0x5a90 kernel/locking/lockdep.c:3061 validate_chain kernel/locking/lockdep.c:3676 [inline] __lock_acquire+0x4307/0x6040 kernel/locking/lockdep.c:4902 lock_acquire+0x17f/0x720 kernel/locking/lockdep.c:5512 __mutex_lock_common+0x1bd/0x2e50 kernel/locking/mutex.c:949 __mutex_lock kernel/locking/mutex.c:1096 [inline] mutex_lock_nested+0x1a/0x20 kernel/locking/mutex.c:1111 brd_probe+0x3a/0x1f0 drivers/block/brd.c:441 blk_request_module+0x19d/0x1c0 block/genhd.c:692 blkdev_get_no_open+0x5c/0x220 fs/block_dev.c:1371 blkdev_get_by_dev+0x82/0x640 fs/block_dev.c:1439 blkdev_open+0x132/0x2c0 fs/block_dev.c:1548 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:1187 do_sys_open fs/open.c:1203 [inline] __do_sys_openat fs/open.c:1219 [inline] __se_sys_openat fs/open.c:1214 [inline] __x64_sys_openat+0x243/0x290 fs/open.c:1214 do_syscall_64+0x3f/0xb0 arch/x86/entry/common.c:47 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x445359 Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 81 14 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 b8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f921850a2f8 EFLAGS: 00000246 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 00000000004cc4f0 RCX: 0000000000445359 RDX: 0000000000000000 RSI: 0000000020002040 RDI: 00000000ffffff9c