====================================================== WARNING: possible circular locking dependency detected 5.13.0-syzkaller #0 Not tainted ------------------------------------------------------ syz-executor.0/8469 is trying to acquire lock: ffffffff8cc7c968 (loop_ctl_mutex){+.+.}-{3:3}, at: loop_probe+0xc7/0x150 drivers/block/loop.c:2397 but task is already holding lock: ffffffff8c9e9ba8 (major_names_lock){+.+.}-{3:3}, at: blk_request_module+0x25/0x1d0 block/genhd.c:657 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+0x12a/0x10a0 kernel/locking/mutex.c:1104 __register_blkdev+0x2b/0x3e0 block/genhd.c:216 register_mtd_blktrans+0x85/0x3c0 drivers/mtd/mtd_blkdevs.c:531 do_one_initcall+0x103/0x650 init/main.c:1246 do_initcall_level init/main.c:1319 [inline] do_initcalls init/main.c:1335 [inline] do_basic_setup init/main.c:1355 [inline] kernel_init_freeable+0x6b8/0x741 init/main.c:1557 kernel_init+0x1a/0x1d0 init/main.c:1449 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 -> #2 (mtd_table_mutex){+.+.}-{3:3}: __mutex_lock_common kernel/locking/mutex.c:959 [inline] __mutex_lock+0x12a/0x10a0 kernel/locking/mutex.c:1104 blktrans_open+0x69/0x600 drivers/mtd/mtd_blkdevs.c:210 blkdev_get_whole+0xa1/0x420 fs/block_dev.c:1251 blkdev_get_by_dev.part.0+0x30c/0xdd0 fs/block_dev.c:1415 blkdev_get_by_dev fs/block_dev.c:1504 [inline] blkdev_open+0x295/0x300 fs/block_dev.c:1510 do_dentry_open+0x4c8/0x11c0 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:1195 do_sys_open fs/open.c:1211 [inline] __do_sys_open fs/open.c:1219 [inline] __se_sys_open fs/open.c:1215 [inline] __x64_sys_open+0x119/0x1c0 fs/open.c:1215 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae -> #1 (&disk->open_mutex){+.+.}-{3:3}: __mutex_lock_common kernel/locking/mutex.c:959 [inline] __mutex_lock+0x12a/0x10a0 kernel/locking/mutex.c:1104 del_gendisk+0x8b/0x770 block/genhd.c:587 loop_remove drivers/block/loop.c:2344 [inline] loop_control_ioctl drivers/block/loop.c:2443 [inline] loop_control_ioctl+0x3e7/0x480 drivers/block/loop.c:2403 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:1069 [inline] __se_sys_ioctl fs/ioctl.c:1055 [inline] __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:1055 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae -> #0 (loop_ctl_mutex){+.+.}-{3:3}: check_prev_add kernel/locking/lockdep.c:3051 [inline] check_prevs_add kernel/locking/lockdep.c:3174 [inline] validate_chain kernel/locking/lockdep.c:3789 [inline] __lock_acquire+0x2a07/0x54a0 kernel/locking/lockdep.c:5015 lock_acquire kernel/locking/lockdep.c:5625 [inline] lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5590 __mutex_lock_common kernel/locking/mutex.c:959 [inline] __mutex_lock+0x12a/0x10a0 kernel/locking/mutex.c:1104 loop_probe+0xc7/0x150 drivers/block/loop.c:2397 blk_request_module+0x111/0x1d0 block/genhd.c:660 blkdev_get_no_open+0x1d5/0x250 fs/block_dev.c:1332 blkdev_get_by_dev.part.0+0x25/0xdd0 fs/block_dev.c:1395 blkdev_get_by_dev fs/block_dev.c:1504 [inline] blkdev_open+0x295/0x300 fs/block_dev.c:1510 do_dentry_open+0x4c8/0x11c0 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:1195 do_sys_open fs/open.c:1211 [inline] __do_sys_openat fs/open.c:1227 [inline] __se_sys_openat fs/open.c:1222 [inline] __x64_sys_openat+0x13f/0x1f0 fs/open.c:1222 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 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 syz-executor.0/8469: #0: ffffffff8c9e9ba8 (major_names_lock){+.+.}-{3:3}, at: blk_request_module+0x25/0x1d0 block/genhd.c:657 stack backtrace: CPU: 0 PID: 8469 Comm: syz-executor.0 Not tainted 5.13.0-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_lvl+0xcd/0x134 lib/dump_stack.c:96 check_noncircular+0x25f/0x2e0 kernel/locking/lockdep.c:2131 check_prev_add kernel/locking/lockdep.c:3051 [inline] check_prevs_add kernel/locking/lockdep.c:3174 [inline] validate_chain kernel/locking/lockdep.c:3789 [inline] __lock_acquire+0x2a07/0x54a0 kernel/locking/lockdep.c:5015 lock_acquire kernel/locking/lockdep.c:5625 [inline] lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5590 __mutex_lock_common kernel/locking/mutex.c:959 [inline] __mutex_lock+0x12a/0x10a0 kernel/locking/mutex.c:1104 loop_probe+0xc7/0x150 drivers/block/loop.c:2397 blk_request_module+0x111/0x1d0 block/genhd.c:660 blkdev_get_no_open+0x1d5/0x250 fs/block_dev.c:1332 blkdev_get_by_dev.part.0+0x25/0xdd0 fs/block_dev.c:1395 blkdev_get_by_dev fs/block_dev.c:1504 [inline] blkdev_open+0x295/0x300 fs/block_dev.c:1510 do_dentry_open+0x4c8/0x11c0 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:1195 do_sys_open fs/open.c:1211 [inline] __do_sys_openat fs/open.c:1227 [inline] __se_sys_openat fs/open.c:1222 [inline] __x64_sys_openat+0x13f/0x1f0 fs/open.c:1222 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x4196c4 Code: 84 00 00 00 00 00 44 89 54 24 0c e8 96 f9 ff ff 44 8b 54 24 0c 44 89 e2 48 89 ee 41 89 c0 bf 9c ff ff ff b8 01 01 00 00 0f 05 <48> 3d 00 f0 ff ff 77 34 44 89 c7 89 44 24 0c e8 c8 f9 ff ff 8b 44 RSP: 002b:0000000000a9fcf0 EFLAGS: 00000293 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 0000000000a9fe00 RCX: 00000000004196c4 RDX: 0000000000000002 RSI: 0000000000a9fe40 RDI: 00000000ffffff9c RBP: 0000000000a9fe40 R08: 0000000000000000 R09: 0000000000a9fc00 R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000002 R13: 000000000008ea66 R14: 0000000000000000 R15: 0000000000a9fe40