====================================================== WARNING: possible circular locking dependency detected 5.12.0-rc4-syzkaller #0 Not tainted ------------------------------------------------------ syz-executor873/8376 is trying to acquire lock: ffffffff8ca4aea8 (brd_devices_mutex){+.+.}-{3:3}, at: brd_probe+0x31/0x250 drivers/block/brd.c:430 but task is already holding lock: ffffffff8c7c7788 (major_names_lock){+.+.}-{3:3}, at: blk_request_module+0x25/0x1d0 block/genhd.c:766 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:300 register_mtd_blktrans+0x85/0x3c0 drivers/mtd/mtd_blkdevs.c:534 do_one_initcall+0x103/0x650 init/main.c:1226 do_initcall_level init/main.c:1299 [inline] do_initcalls init/main.c:1315 [inline] do_basic_setup init/main.c:1335 [inline] kernel_init_freeable+0x63e/0x6c2 init/main.c:1537 kernel_init+0xd/0x1b8 init/main.c:1424 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:1302 blkdev_get_by_dev fs/block_dev.c:1454 [inline] blkdev_get_by_dev+0x26c/0x600 fs/block_dev.c:1422 blkdev_open+0x154/0x2b0 fs/block_dev.c:1551 do_dentry_open+0x4b9/0x11b0 fs/open.c:826 do_open fs/namei.c:3365 [inline] path_openat+0x1c0e/0x27e0 fs/namei.c:3498 do_filp_open+0x17e/0x3c0 fs/namei.c:3525 do_sys_openat2+0x16d/0x420 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+0x119/0x1c0 fs/open.c:1207 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 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:1453 [inline] blkdev_get_by_dev+0x261/0x600 fs/block_dev.c:1422 disk_scan_partitions block/genhd.c:493 [inline] register_disk block/genhd.c:540 [inline] __device_add_disk+0x809/0x12c0 block/genhd.c:621 add_disk include/linux/genhd.h:231 [inline] brd_init+0x2e6/0x4ac drivers/block/brd.c:514 do_one_initcall+0x103/0x650 init/main.c:1226 do_initcall_level init/main.c:1299 [inline] do_initcalls init/main.c:1315 [inline] do_basic_setup init/main.c:1335 [inline] kernel_init_freeable+0x63e/0x6c2 init/main.c:1537 kernel_init+0xd/0x1b8 init/main.c:1424 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:2936 [inline] check_prevs_add kernel/locking/lockdep.c:3059 [inline] validate_chain kernel/locking/lockdep.c:3674 [inline] __lock_acquire+0x2b14/0x54c0 kernel/locking/lockdep.c:4900 lock_acquire kernel/locking/lockdep.c:5510 [inline] lock_acquire+0x1ab/0x740 kernel/locking/lockdep.c:5475 __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:430 blk_request_module+0x111/0x1d0 block/genhd.c:769 blkdev_get_no_open+0x225/0x2b0 fs/block_dev.c:1368 blkdev_get_by_dev fs/block_dev.c:1440 [inline] blkdev_get_by_dev+0x1f9/0x600 fs/block_dev.c:1422 blkdev_open+0x154/0x2b0 fs/block_dev.c:1551 do_dentry_open+0x4b9/0x11b0 fs/open.c:826 do_open fs/namei.c:3365 [inline] path_openat+0x1c0e/0x27e0 fs/namei.c:3498 do_filp_open+0x17e/0x3c0 fs/namei.c:3525 do_sys_openat2+0x16d/0x420 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+0x13f/0x1f0 fs/open.c:1214 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 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-executor873/8376: #0: ffffffff8c7c7788 (major_names_lock){+.+.}-{3:3}, at: blk_request_module+0x25/0x1d0 block/genhd.c:766 stack backtrace: CPU: 0 PID: 8376 Comm: syz-executor873 Not tainted 5.12.0-rc4-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+0x141/0x1d7 lib/dump_stack.c:120 check_noncircular+0x25f/0x2e0 kernel/locking/lockdep.c:2127 check_prev_add kernel/locking/lockdep.c:2936 [inline] check_prevs_add kernel/locking/lockdep.c:3059 [inline] validate_chain kernel/locking/lockdep.c:3674 [inline] __lock_acquire+0x2b14/0x54c0 kernel/locking/lockdep.c:4900 lock_acquire kernel/locking/lockdep.c:5510 [inline] lock_acquire+0x1ab/0x740 kernel/locking/lockdep.c:5475 __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:430 blk_request_module+0x111/0x1d0 block/genhd.c:769 blkdev_get_no_open+0x225/0x2b0 fs/block_dev.c:1368 blkdev_get_by_dev fs/block_dev.c:1440 [inline] blkdev_get_by_dev+0x1f9/0x600 fs/block_dev.c:1422 blkdev_open+0x154/0x2b0 fs/block_dev.c:1551 do_dentry_open+0x4b9/0x11b0 fs/open.c:826 do_open fs/namei.c:3365 [inline] path_openat+0x1c0e/0x27e0 fs/namei.c:3498 do_filp_open+0x17e/0x3c0 fs/namei.c:3525 do_sys_openat2+0x16d/0x420 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+0x13f/0x1f0 fs/open.c:1214 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x445399 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:00007f5c99e882f8 EFLAGS: 00000246 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 00000000004cc4f0 RCX: 00000000004453