======================================================
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