====================================================== WARNING: possible circular locking dependency detected 5.14.0-rc5-syzkaller #0 Not tainted ------------------------------------------------------ syz-executor.1/2753 is trying to acquire lock: ffffffff8c483808 (brd_devices_mutex){+.+.}-{3:3}, at: brd_probe+0x31/0xe0 drivers/block/brd.c:431 but task is already holding lock: ffffffff8c1f2548 (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 blkdev_get_by_dev.part.0+0x9d/0xdd0 fs/block_dev.c:1410 blkdev_get_by_dev+0x6b/0x80 fs/block_dev.c:1450 disk_scan_partitions block/genhd.c:388 [inline] register_disk block/genhd.c:435 [inline] __device_add_disk+0xab5/0xd10 block/genhd.c:527 add_disk include/linux/genhd.h:217 [inline] brd_alloc+0x484/0x6b0 drivers/block/brd.c:416 brd_init+0x16f/0x276 drivers/block/brd.c:499 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 -> #0 (brd_devices_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 brd_probe+0x31/0xe0 drivers/block/brd.c:431 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_openat fs/open.c:1236 [inline] __se_sys_openat fs/open.c:1231 [inline] __x64_sys_openat+0x13f/0x1f0 fs/open.c:1231 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: 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-executor.1/2753: #0: ffffffff8c1f2548 (major_names_lock){+.+.}-{3:3}, at: blk_request_module+0x25/0x1d0 block/genhd.c:657 stack backtrace: CPU: 1 PID: 2753 Comm: syz-executor.1 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 brd_probe+0x31/0xe0 drivers/block/brd.c:431 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_openat fs/open.c:1236 [inline] __se_sys_openat fs/open.c:1231 [inline] __x64_sys_openat+0x13f/0x1f0 fs/open.c:1231 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: 0033:0x4665e9 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 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 bc ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f1964a1d188 EFLAGS: 00000246 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 000000000056c038 RCX: 00000000004665e9 RDX: 0000000000006002 RSI: 0000000020002040 RDI: ffffffffffffff9c RBP: 00000000004bfcc4 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056c038 R13: 00007ffdf85bbabf R14: 00007f1964a1d300 R15: 0000000000022000 ---------------- Code disassembly (best guess), 1 bytes skipped: 0: ff c3 inc %ebx 2: 66 2e 0f 1f 84 00 00 nopw %cs:0x0(%rax,%rax,1) 9: 00 00 00 c: 0f 1f 40 00 nopl 0x0(%rax) 10: 48 89 f8 mov %rdi,%rax 13: 48 89 f7 mov %rsi,%rdi 16: 48 89 d6 mov %rdx,%rsi 19: 48 89 ca mov %rcx,%rdx 1c: 4d 89 c2 mov %r8,%r10 1f: 4d 89 c8 mov %r9,%r8 22: 4c 8b 4c 24 08 mov 0x8(%rsp),%r9 27: 0f 05 syscall 29: 48 3d 01 f0 ff ff cmp $0xfffffffffffff001,%rax <-- trapping instruction 2f: 73 01 jae 0x32 31: c3 retq 32: 48 c7 c1 bc ff ff ff mov $0xffffffffffffffbc,%rcx 39: f7 d8 neg %eax 3b: 64 89 01 mov %eax,%fs:(%rcx) 3e: 48 rex.W