====================================================== WARNING: possible circular locking dependency detected 5.13.0-rc2-next-20210518-syzkaller #0 Not tainted ------------------------------------------------------ syz-executor084/8445 is trying to acquire lock: ffffffff8cc71c28 (brd_devices_mutex){+.+.}-{3:3}, at: brd_probe+0x31/0x250 drivers/block/brd.c:442 but task is already holding lock: ffffffff8c9e4b28 (major_names_lock){+.+.}-{3:3}, at: blk_request_module+0x25/0x1d0 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}: __mutex_lock_common kernel/locking/mutex.c:949 [inline] __mutex_lock+0x139/0x1120 kernel/locking/mutex.c:1096 __register_blkdev+0x2b/0x3e0 block/genhd.c:225 register_mtd_blktrans+0x85/0x3c0 drivers/mtd/mtd_blkdevs.c:534 do_one_initcall+0x103/0x650 init/main.c:1290 do_initcall_level init/main.c:1363 [inline] do_initcalls init/main.c:1379 [inline] do_basic_setup init/main.c:1399 [inline] kernel_init_freeable+0x643/0x6cc init/main.c:1601 kernel_init+0xd/0x1c0 init/main.c:1488 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294 -> #2 (mtd_table_mutex){+.+.}-{3:3}: __mutex_lock_common kernel/locking/mutex.c:949 [inline] __mutex_lock+0x139/0x1120 kernel/locking/mutex.c:1096 blktrans_open+0x69/0x600 drivers/mtd/mtd_blkdevs.c:212 __blkdev_get+0x135/0xa30 fs/block_dev.c:1305 blkdev_get_by_dev fs/block_dev.c:1453 [inline] blkdev_get_by_dev+0x200/0x660 fs/block_dev.c:1425 blkdev_open+0x154/0x2b0 fs/block_dev.c:1548 do_dentry_open+0x4b9/0x11c0 fs/open.c:826 do_open fs/namei.c:3361 [inline] path_openat+0x1c09/0x27d0 fs/namei.c:3494 do_filp_open+0x190/0x3d0 fs/namei.c:3521 do_sys_openat2+0x16d/0x420 fs/open.c:1196 do_sys_open fs/open.c:1212 [inline] __do_sys_open fs/open.c:1220 [inline] __se_sys_open fs/open.c:1216 [inline] __x64_sys_open+0x119/0x1c0 fs/open.c:1216 do_syscall_64+0x31/0xb0 arch/x86/entry/common.c:47 entry_SYSCALL_64_after_hwframe+0x44/0xae -> #1 (&bdev->bd_mutex){+.+.}-{3:3}: __mutex_lock_common kernel/locking/mutex.c:949 [inline] __mutex_lock+0x139/0x1120 kernel/locking/mutex.c:1096 blkdev_get_by_dev fs/block_dev.c:1452 [inline] blkdev_get_by_dev+0x1f6/0x660 fs/block_dev.c:1425 disk_scan_partitions block/genhd.c:427 [inline] register_disk block/genhd.c:474 [inline] __device_add_disk+0x7f2/0x1230 block/genhd.c:555 add_disk include/linux/genhd.h:212 [inline] brd_init+0x307/0x4cd drivers/block/brd.c:528 do_one_initcall+0x103/0x650 init/main.c:1290 do_initcall_level init/main.c:1363 [inline] do_initcalls init/main.c:1379 [inline] do_basic_setup init/main.c:1399 [inline] kernel_init_freeable+0x643/0x6cc init/main.c:1601 kernel_init+0xd/0x1c0 init/main.c:1488 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 kernel/locking/lockdep.c:3061 [inline] validate_chain kernel/locking/lockdep.c:3676 [inline] __lock_acquire+0x2a17/0x5230 kernel/locking/lockdep.c:4902 lock_acquire kernel/locking/lockdep.c:5512 [inline] lock_acquire+0x1ab/0x740 kernel/locking/lockdep.c:5477 __mutex_lock_common kernel/locking/mutex.c:949 [inline] __mutex_lock+0x139/0x1120 kernel/locking/mutex.c:1096 brd_probe+0x31/0x250 drivers/block/brd.c:442 blk_request_module+0x111/0x1d0 block/genhd.c:692 blkdev_get_no_open+0x225/0x2b0 fs/block_dev.c:1371 blkdev_get_by_dev fs/block_dev.c:1439 [inline] blkdev_get_by_dev+0x76/0x660 fs/block_dev.c:1425 blkdev_open+0x154/0x2b0 fs/block_dev.c:1548 do_dentry_open+0x4b9/0x11c0 fs/open.c:826 do_open fs/namei.c:3361 [inline] path_openat+0x1c09/0x27d0 fs/namei.c:3494 do_filp_open+0x190/0x3d0 fs/namei.c:3521 do_sys_openat2+0x16d/0x420 fs/open.c:1196 do_sys_open fs/open.c:1212 [inline] __do_sys_openat fs/open.c:1228 [inline] __se_sys_openat fs/open.c:1223 [inline] __x64_sys_openat+0x13f/0x1f0 fs/open.c:1223 do_syscall_64+0x31/0xb0 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-executor084/8445: #0: ffffffff8c9e4b28 (major_names_lock){+.+.}-{3:3}, at: blk_request_module+0x25/0x1d0 block/genhd.c:689 stack backtrace: CPU: 1 PID: 8445 Comm: syz-executor084 Not tainted 5.13.0-rc2-next-20210518-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+0x13e/0x1d6 lib/dump_stack.c:129 check_noncircular+0x25f/0x2e0 kernel/locking/lockdep.c:2129 check_prev_add kernel/locking/lockdep.c:2938 [inline] check_prevs_add kernel/locking/lockdep.c:3061 [inline] validate_chain kernel/locking/lockdep.c:3676 [inline] __lock_acquire+0x2a17/0x5230 kernel/locking/lockdep.c:4902 lock_acquire kernel/locking/lockdep.c:5512 [inline] lock_acquire+0x1ab/0x740 kernel/locking/lockdep.c:5477 __mutex_lock_common kernel/locking/mutex.c:949 [inline] __mutex_lock+0x139/0x1120 kernel/locking/mutex.c:1096 brd_probe+0x31/0x250 drivers/block/brd.c:442 blk_request_module+0x111/0x1d0 block/genhd.c:692 blkdev_get_no_open+0x225/0x2b0 fs/block_dev.c:1371 blkdev_get_by_dev fs/block_dev.c:1439 [inline] blkdev_get_by_dev+0x76/0x660 fs/block_dev.c:1425 blkdev_open+0x154/0x2b0 fs/block_dev.c:1548 do_dentry_open+0x4b9/0x11c0 fs/open.c:826 do_open fs/namei.c:3361 [inline] path_openat+0x1c09/0x27d0 fs/namei.c:3494 do_filp_open+0x190/0x3d0 fs/namei.c:3521 do_sys_openat2+0x16d/0x420 fs/open.c:1196 do_sys_open fs/open.c:1212 [inline] __do_sys_openat fs/open.c:1228 [inline] __se_sys_openat fs/open.c:1223 [inline] __x64_sys_openat+0x13f/0x1f0 fs/open.c:1223 do_syscall_64+0x31/0xb0 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:00007f039e8ab2f8 EFLAGS: 00000246 ORIG_RAX: 0000000000000101 RAX: fffffff