====================================================== WARNING: possible circular locking dependency detected 5.13.0-rc7-syzkaller #0 Not tainted ------------------------------------------------------ systemd-udevd/9827 is trying to acquire lock: ffffffff8ca6de28 (loop_ctl_mutex){+.+.}-{3:3}, at: loop_probe+0xc7/0x150 drivers/block/loop.c:2234 but task is already holding lock: ffffffff8c7e0368 (major_names_lock){+.+.}-{3:3}, at: blk_request_module+0x25/0x1d0 block/genhd.c:680 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:959 [inline] __mutex_lock+0x139/0x10c0 kernel/locking/mutex.c:1104 __register_blkdev+0x2b/0x3e0 block/genhd.c:223 register_mtd_blktrans+0x85/0x3c0 drivers/mtd/mtd_blkdevs.c:534 do_one_initcall+0x103/0x650 init/main.c:1249 do_initcall_level init/main.c:1322 [inline] do_initcalls init/main.c:1338 [inline] do_basic_setup init/main.c:1358 [inline] kernel_init_freeable+0x6c4/0x74d init/main.c:1560 kernel_init+0xd/0x1b8 init/main.c:1447 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:959 [inline] __mutex_lock+0x139/0x10c0 kernel/locking/mutex.c:1104 blktrans_open+0x69/0x600 drivers/mtd/mtd_blkdevs.c:212 __blkdev_get+0x182/0xa30 fs/block_dev.c:1311 blkdev_get_by_dev fs/block_dev.c:1451 [inline] blkdev_get_by_dev+0x200/0x660 fs/block_dev.c:1423 blkdev_open+0x154/0x2b0 fs/block_dev.c:1546 do_dentry_open+0x4b9/0x11b0 fs/open.c:826 do_open fs/namei.c:3361 [inline] path_openat+0x1c0e/0x27e0 fs/namei.c:3494 do_filp_open+0x190/0x3d0 fs/namei.c:3521 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+0x3a/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:959 [inline] __mutex_lock+0x139/0x10c0 kernel/locking/mutex.c:1104 del_gendisk+0x24b/0xa00 block/genhd.c:610 loop_remove drivers/block/loop.c:2180 [inline] loop_control_ioctl drivers/block/loop.c:2280 [inline] loop_control_ioctl+0x3e7/0x4c0 drivers/block/loop.c:2240 __do_compat_sys_ioctl+0x1c7/0x290 fs/ioctl.c:1167 do_syscall_32_irqs_on arch/x86/entry/common.c:78 [inline] __do_fast_syscall_32+0x67/0xe0 arch/x86/entry/common.c:143 do_fast_syscall_32+0x2f/0x70 arch/x86/entry/common.c:168 entry_SYSENTER_compat_after_hwframe+0x4d/0x5c -> #0 (loop_ctl_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:959 [inline] __mutex_lock+0x139/0x10c0 kernel/locking/mutex.c:1104 loop_probe+0xc7/0x150 drivers/block/loop.c:2234 blk_request_module+0x111/0x1d0 block/genhd.c:683 blkdev_get_no_open+0x1d8/0x250 fs/block_dev.c:1374 blkdev_get_by_dev fs/block_dev.c:1437 [inline] blkdev_get_by_dev+0x76/0x660 fs/block_dev.c:1423 blkdev_open+0x154/0x2b0 fs/block_dev.c:1546 do_dentry_open+0x4b9/0x11b0 fs/open.c:826 do_open fs/namei.c:3361 [inline] path_openat+0x1c0e/0x27e0 fs/namei.c:3494 do_filp_open+0x190/0x3d0 fs/namei.c:3521 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+0x3a/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: 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 systemd-udevd/9827: #0: ffffffff8c7e0368 (major_names_lock){+.+.}-{3:3}, at: blk_request_module+0x25/0x1d0 block/genhd.c:680 stack backtrace: CPU: 0 PID: 9827 Comm: systemd-udevd Not tainted 5.13.0-rc7-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: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:959 [inline] __mutex_lock+0x139/0x10c0 kernel/locking/mutex.c:1104 loop_probe+0xc7/0x150 drivers/block/loop.c:2234 blk_request_module+0x111/0x1d0 block/genhd.c:683 blkdev_get_no_open+0x1d8/0x250 fs/block_dev.c:1374 blkdev_get_by_dev fs/block_dev.c:1437 [inline] blkdev_get_by_dev+0x76/0x660 fs/block_dev.c:1423 blkdev_open+0x154/0x2b0 fs/block_dev.c:1546 do_dentry_open+0x4b9/0x11b0 fs/open.c:826 do_open fs/namei.c:3361 [inline] path_openat+0x1c0e/0x27e0 fs/namei.c:3494 do_filp_open+0x190/0x3d0 fs/namei.c:3521 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+0x3a/0xb0 arch/x86/entry/common.c:47 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x7f6a9d6f5840 Code: 73 01 c3 48 8b 0d 68 77 20 00 f7 d8 64 89 01 48 83 c8 ff c3 66 0f 1f 44 00 00 83 3d 89 bb 20 00 00 75 10 b8 02 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 31 c3 48 83 ec 08 e8 1e f6 ff ff 48 89 04 24 RSP: 002b:00007fff913fbaa8 EFLAGS: 00000246 ORIG_RAX: 0000000000000002 RAX: ffffffffffffffda RBX: 000055e14d4a7f80 RCX: 00007f6a9d6f5840 RDX: 000055e14d2b6fe3 RSI: 00000000000a0800 RDI: 000055e14d4a7f60 RBP: 00007fff913fbc20 R08: 000055e14d2b6670 R09: 0000000000000010 R10: 000055e14d2b6d0c R11: 0000000000000246 R12: 00007fff913fbb70 R13: 000055e14d4a7cf0 R14: 0000000000000003 R15: 000000000000000e