====================================================== WARNING: possible circular locking dependency detected 5.14.0-rc5-syzkaller #0 Not tainted ------------------------------------------------------ systemd-udevd/4872 is trying to acquire lock: ffffffff8c486b88 (loop_ctl_mutex){+.+.}-{3:3}, at: loop_add+0x9c/0x8c0 drivers/block/loop.c:2316 but task is already holding lock: ffffffff8c1f3fe8 (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:1282 do_initcall_level init/main.c:1355 [inline] do_initcalls init/main.c:1371 [inline] do_basic_setup init/main.c:1391 [inline] kernel_init_freeable+0x6b8/0x741 init/main.c:1593 kernel_init+0x1a/0x1d0 init/main.c:1485 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:1253 blkdev_get_by_dev.part.0+0x30c/0xdd0 fs/block_dev.c:1417 blkdev_get_by_dev fs/block_dev.c:1506 [inline] blkdev_open+0x295/0x300 fs/block_dev.c:1512 do_dentry_open+0x4c8/0x11d0 fs/open.c:826 do_open fs/namei.c:3374 [inline] path_openat+0x1c23/0x27f0 fs/namei.c:3507 do_filp_open+0x1aa/0x400 fs/namei.c:3534 do_sys_openat2+0x16d/0x420 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+0x119/0x1c0 fs/open.c:1224 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:2413 [inline] loop_control_remove drivers/block/loop.c:2462 [inline] loop_control_ioctl+0x3b5/0x450 drivers/block/loop.c:2494 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_add+0x9c/0x8c0 drivers/block/loop.c:2316 loop_probe+0x6a/0x80 drivers/block/loop.c:2426 blk_request_module+0x111/0x1d0 block/genhd.c:660 blkdev_get_no_open+0x1d5/0x250 fs/block_dev.c:1334 blkdev_get_by_dev.part.0+0x25/0xdd0 fs/block_dev.c:1397 blkdev_get_by_dev fs/block_dev.c:1506 [inline] blkdev_open+0x295/0x300 fs/block_dev.c:1512 do_dentry_open+0x4c8/0x11d0 fs/open.c:826 do_open fs/namei.c:3374 [inline] path_openat+0x1c23/0x27f0 fs/namei.c:3507 do_filp_open+0x1aa/0x400 fs/namei.c:3534 do_sys_openat2+0x16d/0x420 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+0x119/0x1c0 fs/open.c:1224 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 systemd-udevd/4872: #0: ffffffff8c1f3fe8 (major_names_lock){+.+.}-{3:3}, at: blk_request_module+0x25/0x1d0 block/genhd.c:657 stack backtrace: CPU: 1 PID: 4872 Comm: systemd-udevd Not tainted 5.14.0-rc5-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+0xcd/0x134 lib/dump_stack.c:105 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_add+0x9c/0x8c0 drivers/block/loop.c:2316 loop_probe+0x6a/0x80 drivers/block/loop.c:2426 blk_request_module+0x111/0x1d0 block/genhd.c:660 blkdev_get_no_open+0x1d5/0x250 fs/block_dev.c:1334 blkdev_get_by_dev.part.0+0x25/0xdd0 fs/block_dev.c:1397 blkdev_get_by_dev fs/block_dev.c:1506 [inline] blkdev_open+0x295/0x300 fs/block_dev.c:1512 do_dentry_open+0x4c8/0x11d0 fs/open.c:826 do_open fs/namei.c:3374 [inline] path_openat+0x1c23/0x27f0 fs/namei.c:3507 do_filp_open+0x1aa/0x400 fs/namei.c:3534 do_sys_openat2+0x16d/0x420 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+0x119/0x1c0 fs/open.c:1224 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: 0033:0x7f1c46385840 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:00007fff08031cb8 EFLAGS: 00000246 ORIG_RAX: 0000000000000002 RAX: ffffffffffffffda RBX: 00007fff08031d70 RCX: 00007f1c46385840 RDX: 000055de12f50fe3 RSI: 00000000000a0800 RDI: 000055de134d2610 RBP: 0000000000000000 R08: 000055de12f50670 R09: 0000000000000010 R10: 0000000000000000 R11: 0000000000000246 R12: 00007fff08031e60 R13: 000055de134c2010 R14: 000055de134d4e90 R15: 00007fff08031d30 ---------------- Code disassembly (best guess): 0: 73 01 jae 0x3 2: c3 retq 3: 48 8b 0d 68 77 20 00 mov 0x207768(%rip),%rcx # 0x207772 a: f7 d8 neg %eax c: 64 89 01 mov %eax,%fs:(%rcx) f: 48 83 c8 ff or $0xffffffffffffffff,%rax 13: c3 retq 14: 66 0f 1f 44 00 00 nopw 0x0(%rax,%rax,1) 1a: 83 3d 89 bb 20 00 00 cmpl $0x0,0x20bb89(%rip) # 0x20bbaa 21: 75 10 jne 0x33 23: b8 02 00 00 00 mov $0x2,%eax 28: 0f 05 syscall 2a: 48 3d 01 f0 ff ff cmp $0xfffffffffffff001,%rax <-- trapping instruction 30: 73 31 jae 0x63 32: c3 retq 33: 48 83 ec 08 sub $0x8,%rsp 37: e8 1e f6 ff ff callq 0xfffff65a 3c: 48 89 04 24 mov %rax,(%rsp)