====================================================== WARNING: possible circular locking dependency detected 5.14.0-rc6-syzkaller #0 Not tainted ------------------------------------------------------ syz-executor.1/9984 is trying to acquire lock: ffffffff8ce847c8 (loop_ctl_mutex){+.+.}-{3:3}, at: loop_add+0x89/0x7f0 drivers/block/loop.c:2316 but task is already holding lock: ffffffff8cceb088 (major_names_lock){+.+.}-{3:3}, at: blk_request_module+0x2f/0x1c0 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}: lock_acquire+0x182/0x4a0 kernel/locking/lockdep.c:5625 __mutex_lock_common+0x1ad/0x3770 kernel/locking/mutex.c:959 __mutex_lock kernel/locking/mutex.c:1104 [inline] mutex_lock_nested+0x1a/0x20 kernel/locking/mutex.c:1119 __register_blkdev+0x2c/0x360 block/genhd.c:216 register_mtd_blktrans+0x94/0x3d0 drivers/mtd/mtd_blkdevs.c:531 do_one_initcall+0x197/0x3f0 init/main.c:1282 do_initcall_level+0x14a/0x1f5 init/main.c:1355 do_initcalls+0x4b/0x8c init/main.c:1371 kernel_init_freeable+0x3f1/0x57e init/main.c:1593 kernel_init+0x19/0x2a0 init/main.c:1485 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 -> #2 (mtd_table_mutex){+.+.}-{3:3}: lock_acquire+0x182/0x4a0 kernel/locking/lockdep.c:5625 __mutex_lock_common+0x1ad/0x3770 kernel/locking/mutex.c:959 __mutex_lock kernel/locking/mutex.c:1104 [inline] mutex_lock_nested+0x1a/0x20 kernel/locking/mutex.c:1119 blktrans_open+0x61/0x430 drivers/mtd/mtd_blkdevs.c:210 blkdev_get_whole+0x94/0x500 fs/block_dev.c:1253 blkdev_get_by_dev+0x339/0xdc0 fs/block_dev.c:1417 blkdev_open+0x132/0x2c0 fs/block_dev.c:1512 do_dentry_open+0x7cb/0x1020 fs/open.c:826 do_open fs/namei.c:3374 [inline] path_openat+0x27e7/0x36b0 fs/namei.c:3507 do_filp_open+0x253/0x4d0 fs/namei.c:3534 do_sys_openat2+0x124/0x460 fs/open.c:1204 do_sys_open fs/open.c:1220 [inline] __do_sys_open fs/open.c:1228 [inline] __se_sys_open fs/open.c:1224 [inline] __x64_sys_open+0x221/0x270 fs/open.c:1224 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae -> #1 (&disk->open_mutex){+.+.}-{3:3}: lock_acquire+0x182/0x4a0 kernel/locking/lockdep.c:5625 __mutex_lock_common+0x1ad/0x3770 kernel/locking/mutex.c:959 __mutex_lock kernel/locking/mutex.c:1104 [inline] mutex_lock_nested+0x1a/0x20 kernel/locking/mutex.c:1119 del_gendisk+0x86/0x610 block/genhd.c:587 loop_remove drivers/block/loop.c:2413 [inline] loop_control_remove drivers/block/loop.c:2462 [inline] loop_control_ioctl+0x409/0x510 drivers/block/loop.c:2494 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:1069 [inline] __se_sys_ioctl+0xfb/0x170 fs/ioctl.c:1055 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x3d/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+0x4f9/0x5b30 kernel/locking/lockdep.c:3174 validate_chain kernel/locking/lockdep.c:3789 [inline] __lock_acquire+0x4476/0x6100 kernel/locking/lockdep.c:5015 lock_acquire+0x182/0x4a0 kernel/locking/lockdep.c:5625 __mutex_lock_common+0x1ad/0x3770 kernel/locking/mutex.c:959 __mutex_lock kernel/locking/mutex.c:1104 [inline] mutex_lock_killable_nested+0x1a/0x20 kernel/locking/mutex.c:1134 loop_add+0x89/0x7f0 drivers/block/loop.c:2316 blk_request_module+0x19d/0x1c0 block/genhd.c:660 blkdev_get_no_open+0x44/0x1f0 fs/block_dev.c:1334 blkdev_get_by_dev+0x89/0xdc0 fs/block_dev.c:1397 blkdev_open+0x132/0x2c0 fs/block_dev.c:1512 do_dentry_open+0x7cb/0x1020 fs/open.c:826 do_open fs/namei.c:3374 [inline] path_openat+0x27e7/0x36b0 fs/namei.c:3507 do_filp_open+0x253/0x4d0 fs/namei.c:3534 do_sys_openat2+0x124/0x460 fs/open.c:1204 do_sys_open fs/open.c:1220 [inline] __do_sys_openat fs/open.c:1236 [inline] __se_sys_openat fs/open.c:1231 [inline] __x64_sys_openat+0x243/0x290 fs/open.c:1231 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x3d/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.1/9984: #0: ffffffff8cceb088 (major_names_lock){+.+.}-{3:3}, at: blk_request_module+0x2f/0x1c0 block/genhd.c:657 stack backtrace: CPU: 0 PID: 9984 Comm: syz-executor.1 Not tainted 5.14.0-rc6-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+0x1ae/0x29f lib/dump_stack.c:105 print_circular_bug+0xb17/0xdc0 kernel/locking/lockdep.c:2009 check_noncircular+0x2cc/0x390 kernel/locking/lockdep.c:2131 check_prev_add kernel/locking/lockdep.c:3051 [inline] check_prevs_add+0x4f9/0x5b30 kernel/locking/lockdep.c:3174 validate_chain kernel/locking/lockdep.c:3789 [inline] __lock_acquire+0x4476/0x6100 kernel/locking/lockdep.c:5015 lock_acquire+0x182/0x4a0 kernel/locking/lockdep.c:5625 __mutex_lock_common+0x1ad/0x3770 kernel/locking/mutex.c:959 __mutex_lock kernel/locking/mutex.c:1104 [inline] mutex_lock_killable_nested+0x1a/0x20 kernel/locking/mutex.c:1134 loop_add+0x89/0x7f0 drivers/block/loop.c:2316 blk_request_module+0x19d/0x1c0 block/genhd.c:660 blkdev_get_no_open+0x44/0x1f0 fs/block_dev.c:1334 blkdev_get_by_dev+0x89/0xdc0 fs/block_dev.c:1397 blkdev_open+0x132/0x2c0 fs/block_dev.c:1512 do_dentry_open+0x7cb/0x1020 fs/open.c:826 do_open fs/namei.c:3374 [inline] path_openat+0x27e7/0x36b0 fs/namei.c:3507 do_filp_open+0x253/0x4d0 fs/namei.c:3534 do_sys_openat2+0x124/0x460 fs/open.c:1204 do_sys_open fs/open.c:1220 [inline] __do_sys_openat fs/open.c:1236 [inline] __se_sys_openat fs/open.c:1231 [inline] __x64_sys_openat+0x243/0x290 fs/open.c:1231 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x4196d4 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:00007f25affc7ed0 EFLAGS: 00000293 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 00000000004afcc0 RCX: 00000000004196d4 RDX: 0000000000000002 RSI: 00007f25affc8000 RDI: 00000000ffffff9c RBP: 00007f25affc8000 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000002 R13: 0000000000000005 R14: 0000000020000088 R15: 0000000000000003 ---------------- Code disassembly (best guess): 0: 84 00 test %al,(%rax) 2: 00 00 add %al,(%rax) 4: 00 00 add %al,(%rax) 6: 44 89 54 24 0c mov %r10d,0xc(%rsp) b: e8 96 f9 ff ff callq 0xfffff9a6 10: 44 8b 54 24 0c mov 0xc(%rsp),%r10d 15: 44 89 e2 mov %r12d,%edx 18: 48 89 ee mov %rbp,%rsi 1b: 41 89 c0 mov %eax,%r8d 1e: bf 9c ff ff ff mov $0xffffff9c,%edi 23: b8 01 01 00 00 mov $0x101,%eax 28: 0f 05 syscall 2a: 48 3d 00 f0 ff ff cmp $0xfffffffffffff000,%rax <-- trapping instruction 30: 77 34 ja 0x66 32: 44 89 c7 mov %r8d,%edi 35: 89 44 24 0c mov %eax,0xc(%rsp) 39: e8 c8 f9 ff ff callq 0xfffffa06 3e: 8b .byte 0x8b 3f: 44 rex.R