Hello, syzbot found the following issue on: HEAD commit: 306e57988197 Merge patch "riscv: defconfig: run savedefcon.. git tree: git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux.git for-next console output: https://syzkaller.appspot.com/x/log.txt?x=10721e82580000 kernel config: https://syzkaller.appspot.com/x/.config?x=618b9468db3872f5 dashboard link: https://syzkaller.appspot.com/bug?extid=ea702c2366971b7fc6e4 compiler: riscv64-linux-gnu-gcc (Debian 12.2.0-13) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40 userspace arch: riscv64 Unfortunately, I don't have any reproducer for this issue yet. Downloadable assets: disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/a741b348759c/non_bootable_disk-306e5798.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/5fee9bbe87f3/vmlinux-306e5798.xz kernel image: https://storage.googleapis.com/syzbot-assets/e959580bb405/Image-306e5798.xz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+ea702c2366971b7fc6e4@xxxxxxxxxxxxxxxxxxxxxxxxx ====================================================== WARNING: possible circular locking dependency detected 6.16.0-rc1-syzkaller-g306e57988197 #0 Not tainted ------------------------------------------------------ syz.4.1189/8748 is trying to acquire lock: ffffaf801a39a230 (&nbd->config_lock){+.+.}-{4:4}, at: nbd_open+0x3c0/0x6fe drivers/block/nbd.c:1703 but task is already holding lock: ffffffff88e269e8 (nbd_index_mutex){+.+.}-{4:4}, at: nbd_open+0x98/0x6fe drivers/block/nbd.c:1690 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #3 (nbd_index_mutex){+.+.}-{4:4}: lock_acquire kernel/locking/lockdep.c:5871 [inline] lock_acquire+0x1ac/0x448 kernel/locking/lockdep.c:5828 __mutex_lock_common kernel/locking/mutex.c:602 [inline] __mutex_lock+0x166/0x1292 kernel/locking/mutex.c:747 mutex_lock_nested+0x14/0x1c kernel/locking/mutex.c:799 nbd_open+0x98/0x6fe drivers/block/nbd.c:1690 blkdev_get_whole+0x8a/0x266 block/bdev.c:730 bdev_open+0x292/0xce6 block/bdev.c:957 blkdev_open+0x264/0x39a block/fops.c:676 do_dentry_open+0x97e/0x171e fs/open.c:964 vfs_open+0xbe/0x380 fs/open.c:1094 do_open fs/namei.c:3887 [inline] path_openat+0x1bd8/0x2a82 fs/namei.c:4046 do_filp_open+0x19c/0x380 fs/namei.c:4073 do_sys_openat2+0x11a/0x1c2 fs/open.c:1437 do_sys_open fs/open.c:1452 [inline] __do_sys_openat fs/open.c:1468 [inline] __se_sys_openat fs/open.c:1463 [inline] __riscv_sys_openat+0x178/0x1fe fs/open.c:1463 syscall_handler+0x94/0x118 arch/riscv/include/asm/syscall.h:112 do_trap_ecall_u+0x396/0x530 arch/riscv/kernel/traps.c:341 handle_exception+0x146/0x152 arch/riscv/kernel/entry.S:197 -> #2 (&disk->open_mutex){+.+.}-{4:4}: lock_acquire kernel/locking/lockdep.c:5871 [inline] lock_acquire+0x1ac/0x448 kernel/locking/lockdep.c:5828 __mutex_lock_common kernel/locking/mutex.c:602 [inline] __mutex_lock+0x166/0x1292 kernel/locking/mutex.c:747 mutex_lock_nested+0x14/0x1c kernel/locking/mutex.c:799 __del_gendisk+0x132/0xac6 block/genhd.c:706 del_gendisk+0xf6/0x19a block/genhd.c:819 nbd_dev_remove+0x3c/0xf2 drivers/block/nbd.c:268 nbd_dev_remove_work+0x1c/0x26 drivers/block/nbd.c:284 process_one_work+0x96a/0x1f32 kernel/workqueue.c:3238 process_scheduled_works kernel/workqueue.c:3321 [inline] worker_thread+0x5ce/0xde8 kernel/workqueue.c:3402 kthread+0x39c/0x7d4 kernel/kthread.c:464 ret_from_fork_kernel+0x2a/0xbb2 arch/riscv/kernel/process.c:214 ret_from_fork_kernel_asm+0x16/0x18 arch/riscv/kernel/entry.S:327 -> #1 (&set->update_nr_hwq_lock){++++}-{4:4}: lock_acquire kernel/locking/lockdep.c:5871 [inline] lock_acquire+0x1ac/0x448 kernel/locking/lockdep.c:5828 down_write+0x9c/0x19a kernel/locking/rwsem.c:1577 blk_mq_update_nr_hw_queues+0x3e/0xb86 block/blk-mq.c:5041 nbd_start_device+0x140/0xb2c drivers/block/nbd.c:1476 nbd_genl_connect+0xae0/0x1b24 drivers/block/nbd.c:2201 genl_family_rcv_msg_doit+0x206/0x2e6 net/netlink/genetlink.c:1115 genl_family_rcv_msg net/netlink/genetlink.c:1195 [inline] genl_rcv_msg+0x514/0x78e net/netlink/genetlink.c:1210 netlink_rcv_skb+0x206/0x3be net/netlink/af_netlink.c:2534 genl_rcv+0x36/0x4c net/netlink/genetlink.c:1219 netlink_unicast_kernel net/netlink/af_netlink.c:1313 [inline] netlink_unicast+0x4f0/0x82c net/netlink/af_netlink.c:1339 netlink_sendmsg+0x85e/0xdd6 net/netlink/af_netlink.c:1883 sock_sendmsg_nosec net/socket.c:712 [inline] __sock_sendmsg+0xcc/0x160 net/socket.c:727 ____sys_sendmsg+0x63e/0x79c net/socket.c:2566 ___sys_sendmsg+0x144/0x1e6 net/socket.c:2620 __sys_sendmsg+0x188/0x246 net/socket.c:2652 __do_sys_sendmsg net/socket.c:2657 [inline] __se_sys_sendmsg net/socket.c:2655 [inline] __riscv_sys_sendmsg+0x70/0xa2 net/socket.c:2655 syscall_handler+0x94/0x118 arch/riscv/include/asm/syscall.h:112 do_trap_ecall_u+0x396/0x530 arch/riscv/kernel/traps.c:341 handle_exception+0x146/0x152 arch/riscv/kernel/entry.S:197 -> #0 (&nbd->config_lock){+.+.}-{4:4}: check_noncircular+0x132/0x146 kernel/locking/lockdep.c:2178 check_prev_add kernel/locking/lockdep.c:3168 [inline] check_prevs_add kernel/locking/lockdep.c:3287 [inline] validate_chain kernel/locking/lockdep.c:3911 [inline] __lock_acquire+0x12b2/0x24ea kernel/locking/lockdep.c:5240 lock_acquire kernel/locking/lockdep.c:5871 [inline] lock_acquire+0x1ac/0x448 kernel/locking/lockdep.c:5828 __mutex_lock_common kernel/locking/mutex.c:602 [inline] __mutex_lock+0x166/0x1292 kernel/locking/mutex.c:747 mutex_lock_nested+0x14/0x1c kernel/locking/mutex.c:799 nbd_open+0x3c0/0x6fe drivers/block/nbd.c:1703 blkdev_get_whole+0x8a/0x266 block/bdev.c:730 bdev_open+0x292/0xce6 block/bdev.c:957 blkdev_open+0x264/0x39a block/fops.c:676 do_dentry_open+0x97e/0x171e fs/open.c:964 vfs_open+0xbe/0x380 fs/open.c:1094 do_open fs/namei.c:3887 [inline] path_openat+0x1bd8/0x2a82 fs/namei.c:4046 do_filp_open+0x19c/0x380 fs/namei.c:4073 do_sys_openat2+0x11a/0x1c2 fs/open.c:1437 do_sys_open fs/open.c:1452 [inline] __do_sys_openat fs/open.c:1468 [inline] __se_sys_openat fs/open.c:1463 [inline] __riscv_sys_openat+0x178/0x1fe fs/open.c:1463 syscall_handler+0x94/0x118 arch/riscv/include/asm/syscall.h:112 do_trap_ecall_u+0x396/0x530 arch/riscv/kernel/traps.c:341 handle_exception+0x146/0x152 arch/riscv/kernel/entry.S:197 other info that might help us debug this: Chain exists of: &nbd->config_lock --> &disk->open_mutex --> nbd_index_mutex Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(nbd_index_mutex); lock(&disk->open_mutex); lock(nbd_index_mutex); lock(&nbd->config_lock); *** DEADLOCK *** 2 locks held by syz.4.1189/8748: #0: ffffaf801a3a2358 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_open+0x3d0/0xce6 block/bdev.c:945 #1: ffffffff88e269e8 (nbd_index_mutex){+.+.}-{4:4}, at: nbd_open+0x98/0x6fe drivers/block/nbd.c:1690 stack backtrace: CPU: 0 UID: 0 PID: 8748 Comm: syz.4.1189 Not tainted 6.16.0-rc1-syzkaller-g306e57988197 #0 PREEMPT Hardware name: riscv-virtio,qemu (DT) Call Trace: [<ffffffff80078bbe>] dump_backtrace+0x2e/0x3c arch/riscv/kernel/stacktrace.c:132 [<ffffffff8000327a>] show_stack+0x30/0x3c arch/riscv/kernel/stacktrace.c:138 [<ffffffff8006103e>] __dump_stack lib/dump_stack.c:94 [inline] [<ffffffff8006103e>] dump_stack_lvl+0x12e/0x1a6 lib/dump_stack.c:120 [<ffffffff800610d2>] dump_stack+0x1c/0x24 lib/dump_stack.c:129 [<ffffffff802ce116>] print_circular_bug+0x254/0x29a kernel/locking/lockdep.c:2046 [<ffffffff802ce28e>] check_noncircular+0x132/0x146 kernel/locking/lockdep.c:2178 [<ffffffff802d1468>] check_prev_add kernel/locking/lockdep.c:3168 [inline] [<ffffffff802d1468>] check_prevs_add kernel/locking/lockdep.c:3287 [inline] [<ffffffff802d1468>] validate_chain kernel/locking/lockdep.c:3911 [inline] [<ffffffff802d1468>] __lock_acquire+0x12b2/0x24ea kernel/locking/lockdep.c:5240 [<ffffffff802d32de>] lock_acquire kernel/locking/lockdep.c:5871 [inline] [<ffffffff802d32de>] lock_acquire+0x1ac/0x448 kernel/locking/lockdep.c:5828 [<ffffffff8630e424>] __mutex_lock_common kernel/locking/mutex.c:602 [inline] [<ffffffff8630e424>] __mutex_lock+0x166/0x1292 kernel/locking/mutex.c:747 [<ffffffff8630f564>] mutex_lock_nested+0x14/0x1c kernel/locking/mutex.c:799 [<ffffffff82c3fb3a>] nbd_open+0x3c0/0x6fe drivers/block/nbd.c:1703 [<ffffffff81531ca6>] blkdev_get_whole+0x8a/0x266 block/bdev.c:730 [<ffffffff81532f2e>] bdev_open+0x292/0xce6 block/bdev.c:957 [<ffffffff81539df6>] blkdev_open+0x264/0x39a block/fops.c:676 [<ffffffff80be5b4e>] do_dentry_open+0x97e/0x171e fs/open.c:964 [<ffffffff80bea7aa>] vfs_open+0xbe/0x380 fs/open.c:1094 [<ffffffff80c3d1ba>] do_open fs/namei.c:3887 [inline] [<ffffffff80c3d1ba>] path_openat+0x1bd8/0x2a82 fs/namei.c:4046 [<ffffffff80c3e200>] do_filp_open+0x19c/0x380 fs/namei.c:4073 [<ffffffff80beb5f4>] do_sys_openat2+0x11a/0x1c2 fs/open.c:1437 [<ffffffff80bebff6>] do_sys_open fs/open.c:1452 [inline] [<ffffffff80bebff6>] __do_sys_openat fs/open.c:1468 [inline] [<ffffffff80bebff6>] __se_sys_openat fs/open.c:1463 [inline] [<ffffffff80bebff6>] __riscv_sys_openat+0x178/0x1fe fs/open.c:1463 [<ffffffff800769ae>] syscall_handler+0x94/0x118 arch/riscv/include/asm/syscall.h:112 [<ffffffff862fcc32>] do_trap_ecall_u+0x396/0x530 arch/riscv/kernel/traps.c:341 [<ffffffff863250ca>] handle_exception+0x146/0x152 arch/riscv/kernel/entry.S:197 --- This report is generated by a bot. It may contain errors. See https://goo.gl/tpsmEJ for more information about syzbot. syzbot engineers can be reached at syzkaller@xxxxxxxxxxxxxxxx. syzbot will keep track of this issue. See: https://goo.gl/tpsmEJ#status for how to communicate with syzbot. If the report is already addressed, let syzbot know by replying with: #syz fix: exact-commit-title If you want to overwrite report's subsystems, reply with: #syz set subsystems: new-subsystem (See the list of subsystem names on the web dashboard) If the report is a duplicate of another one, reply with: #syz dup: exact-subject-of-another-report If you want to undo deduplication, reply with: #syz undup
