From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-ot1-f78.google.com (mail-ot1-f78.google.com [209.85.210.78]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8E3D3392C20 for ; Mon, 16 Mar 2026 12:02:23 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.210.78 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773662545; cv=none; b=t0m4c4bOAOtoj4/pYtsXyRzAvShk2JUQAEZbKwuAp2Edw19OwNJfegXzNyJg/570bUrZXZpf6mzqrx/qivkE7V/IDfT7v+ldYOmo98lPzb7HKmbuYdzoG9mehJy/HopAxW13cCr/UCwJmtvNvxRBj0+QtAuQeDzgbAV9NVVzKMc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773662545; c=relaxed/simple; bh=igZw+d46yvbJOsjKBjv40MT1n0Qwt/+a3rH6JKFK/7w=; h=MIME-Version:Date:Message-ID:Subject:From:To:Content-Type; b=Ew2wFuUBP4KI9jt83LYOFsGYKeuFWqmspkgubiZyfQWvUVDecGUT0DyBawvs9T2ioElxmMdUm3EIn/A+QRpf8ZX2N+oqsP0VULNmkMZYbSjkhOgCIW+E1DOzkqJUcRYxLU8g1ivuLZpMc3B4bWImtUj7SeQdHzBGz1HoKHxp5II= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=syzkaller.appspotmail.com; spf=pass smtp.mailfrom=M3KW2WVRGUFZ5GODRSRYTGD7.apphosting.bounces.google.com; arc=none smtp.client-ip=209.85.210.78 Authentication-Results: smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=syzkaller.appspotmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=M3KW2WVRGUFZ5GODRSRYTGD7.apphosting.bounces.google.com Received: by mail-ot1-f78.google.com with SMTP id 46e09a7af769-7d74cd19998so61102920a34.2 for ; Mon, 16 Mar 2026 05:02:23 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1773662542; x=1774267342; h=to:from:subject:message-id:date:mime-version:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=lxLpN4U3Cphxh4Wh3bfLWg5im4cwZ1APokA6M9ffMEY=; b=gSRAg22GoG/rMWbxMfj71ZdeZeNmsx6wtGhj8V4zOyg7OsI6HJUZ0h+76GsOC8Xile b4DoZ1m6a8ik8Rhco45hapi8LTLkeLMKwrVv4O7OwOgujgs9B/j1LXm96Obzen6kD3RV HvC2fKRbNaBbl7IJiUsaOXlcq5xQxRWoibyXU5yLspTS6Yacq2IyixRzY8loUYcqFbPq Zxo4+nlb1j37gL5KKIv26zmLof2yHOBoipcOQldOrL1lHiOriJjsuLcaK30l6CxQQpEu C8nj7EDzDUzg4711jJQ+Ov2PtJdXFxAcvwfPdEyWJSSje9M9sOaMjyNSJgxvZCifkD2d ZK8Q== X-Forwarded-Encrypted: i=1; AJvYcCWVw0J5ofWJqUGp4YxVvdsPW0qCAwNo1T9XGnIgTEo3E7446TUT+18jj0YOCCH28bJhQ+f/nf9RikIfWw==@lists.linux.dev X-Gm-Message-State: AOJu0Yx+/kvBp/Izeilz+HDuRPPoTf85h5aMSiAxH3jSvE8iBlaBw2zm Y0ki8HEo7xBlgv6QjtrPFk0N40JFwPEE7ehOLc5yE6Cb+ZGzsjMcPqJmBj8HGI/7Jpsej8cle0k NCBcgtNyd8kXo1CI5vFIc/0BDaJAWv1X3R/A8F/jsyn58CRBavXzAS7sgA5M= Precedence: bulk X-Mailing-List: driver-core@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Received: by 2002:a05:6808:5186:b0:467:3f4:907c with SMTP id 5614622812f47-46757402a73mr6690598b6e.47.1773662541977; Mon, 16 Mar 2026 05:02:21 -0700 (PDT) Date: Mon, 16 Mar 2026 05:02:21 -0700 X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <69b7f14d.050a0220.12d28.015e.GAE@google.com> Subject: [syzbot] [kernel?] possible deadlock in device_create (3) From: syzbot To: dakr@kernel.org, driver-core@lists.linux.dev, gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org, rafael@kernel.org, syzkaller-bugs@googlegroups.com Content-Type: text/plain; charset="UTF-8" Hello, syzbot found the following issue on: HEAD commit: 0257f64bdac7 Merge tag 'pm-7.0-rc4' of git://git.kernel.or.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=17f444d6580000 kernel config: https://syzkaller.appspot.com/x/.config?x=2b9fbb898accd2e4 dashboard link: https://syzkaller.appspot.com/bug?extid=4ba8a624812f10a13c48 compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8 Unfortunately, I don't have any reproducer for this issue yet. Downloadable assets: disk image: https://storage.googleapis.com/syzbot-assets/fe2c2d3a356f/disk-0257f64b.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/814567bbd30d/vmlinux-0257f64b.xz kernel image: https://storage.googleapis.com/syzbot-assets/5cecf46c0268/bzImage-0257f64b.xz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+4ba8a624812f10a13c48@syzkaller.appspotmail.com Dev nbd6: unable to read RDB block 0 nbd6: unable to read partition table ldm_validate_partition_table(): Disk read failed. Dev nbd6: unable to read RDB block 0 nbd6: unable to read partition table ====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Tainted: G L ------------------------------------------------------ udevd/17714 is trying to acquire lock: ffffffff8deedda0 (fs_reclaim){+.+.}-{0:0}, at: might_alloc include/linux/sched/mm.h:317 [inline] ffffffff8deedda0 (fs_reclaim){+.+.}-{0:0}, at: slab_pre_alloc_hook mm/slub.c:4493 [inline] ffffffff8deedda0 (fs_reclaim){+.+.}-{0:0}, at: slab_alloc_node mm/slub.c:4846 [inline] ffffffff8deedda0 (fs_reclaim){+.+.}-{0:0}, at: kmem_cache_alloc_node_noprof+0x4b/0x6e0 mm/slub.c:4921 but task is already holding lock: ffffffff8f50f6f8 (uevent_sock_mutex){+.+.}-{4:4}, at: uevent_net_broadcast_untagged lib/kobject_uevent.c:317 [inline] ffffffff8f50f6f8 (uevent_sock_mutex){+.+.}-{4:4}, at: kobject_uevent_net_broadcast+0x281/0x560 lib/kobject_uevent.c:410 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #9 (uevent_sock_mutex){+.+.}-{4:4}: __mutex_lock_common kernel/locking/rtmutex_api.c:533 [inline] mutex_lock_nested+0x5a/0x1d0 kernel/locking/rtmutex_api.c:552 uevent_net_broadcast_untagged lib/kobject_uevent.c:317 [inline] kobject_uevent_net_broadcast+0x281/0x560 lib/kobject_uevent.c:410 kobject_uevent_env+0x55f/0x9e0 lib/kobject_uevent.c:608 device_add+0x557/0xb80 drivers/base/core.c:3670 device_create_groups_vargs drivers/base/core.c:4371 [inline] device_create+0x269/0x300 drivers/base/core.c:4410 msr_device_create+0x33/0x50 arch/x86/kernel/msr.c:251 cpuhp_invoke_callback+0x445/0x860 kernel/cpu.c:194 cpuhp_thread_fun+0x36b/0x780 kernel/cpu.c:1109 smpboot_thread_fn+0x541/0xa50 kernel/smpboot.c:160 kthread+0x388/0x470 kernel/kthread.c:436 ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 -> #8 (cpuhp_state-up){+.+.}-{0:0}: cpuhp_lock_acquire kernel/cpu.c:103 [inline] cpuhp_thread_fun+0x127/0x780 kernel/cpu.c:1086 smpboot_thread_fn+0x541/0xa50 kernel/smpboot.c:160 kthread+0x388/0x470 kernel/kthread.c:436 ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 -> #7 (cpu_hotplug_lock){++++}-{0:0}: percpu_down_read_internal include/linux/percpu-rwsem.h:53 [inline] percpu_down_read include/linux/percpu-rwsem.h:77 [inline] cpus_read_lock+0x42/0x160 kernel/cpu.c:490 static_key_slow_inc+0x12/0x30 kernel/jump_label.c:190 fl_create net/ipv6/ip6_flowlabel.c:457 [inline] ipv6_flowlabel_get net/ipv6/ip6_flowlabel.c:637 [inline] ipv6_flowlabel_opt+0x160a/0x2340 net/ipv6/ip6_flowlabel.c:740 do_ipv6_setsockopt+0xda7/0x31c0 net/ipv6/ipv6_sockglue.c:936 ipv6_setsockopt+0x59/0x170 net/ipv6/ipv6_sockglue.c:973 do_sock_setsockopt+0x17c/0x1b0 net/socket.c:2322 __sys_setsockopt net/socket.c:2347 [inline] __do_sys_setsockopt net/socket.c:2353 [inline] __se_sys_setsockopt net/socket.c:2350 [inline] __x64_sys_setsockopt+0x143/0x1b0 net/socket.c:2350 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #6 (sk_lock-AF_INET6){+.+.}-{0:0}: lock_sock_nested+0x3e/0x130 net/core/sock.c:3780 lock_sock include/net/sock.h:1709 [inline] inet_shutdown+0x6a/0x390 net/ipv4/af_inet.c:919 nbd_mark_nsock_dead+0x2e9/0x560 drivers/block/nbd.c:318 recv_work+0x1c9d/0x1dc0 drivers/block/nbd.c:1021 process_one_work kernel/workqueue.c:3275 [inline] process_scheduled_works+0xb02/0x1830 kernel/workqueue.c:3358 worker_thread+0xa50/0xfc0 kernel/workqueue.c:3439 kthread+0x388/0x470 kernel/kthread.c:436 ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 -> #5 (&nsock->tx_lock){+.+.}-{4:4}: __mutex_lock_common kernel/locking/rtmutex_api.c:533 [inline] mutex_lock_nested+0x5a/0x1d0 kernel/locking/rtmutex_api.c:552 nbd_handle_cmd drivers/block/nbd.c:1143 [inline] nbd_queue_rq+0x37b/0x1100 drivers/block/nbd.c:1207 blk_mq_dispatch_rq_list+0xa77/0x1910 block/blk-mq.c:2148 __blk_mq_do_dispatch_sched block/blk-mq-sched.c:168 [inline] blk_mq_do_dispatch_sched block/blk-mq-sched.c:182 [inline] __blk_mq_sched_dispatch_requests+0xddb/0x1610 block/blk-mq-sched.c:307 blk_mq_sched_dispatch_requests+0xda/0x1a0 block/blk-mq-sched.c:329 blk_mq_run_hw_queue+0x368/0x520 block/blk-mq.c:2386 blk_mq_dispatch_list+0xd1f/0xe20 include/linux/spinlock_rt.h:-1 blk_mq_flush_plug_list+0x48d/0x570 block/blk-mq.c:2997 __blk_flush_plug+0x3ed/0x4d0 block/blk-core.c:1230 blk_finish_plug block/blk-core.c:1257 [inline] __submit_bio+0x28d/0x580 block/blk-core.c:649 __submit_bio_noacct_mq block/blk-core.c:722 [inline] submit_bio_noacct_nocheck+0x2f4/0xa70 block/blk-core.c:753 submit_bh fs/buffer.c:2826 [inline] block_read_full_folio+0x599/0x830 fs/buffer.c:2444 filemap_read_folio+0x137/0x3b0 mm/filemap.c:2501 do_read_cache_folio+0x2bf/0x560 mm/filemap.c:4101 read_mapping_folio include/linux/pagemap.h:1028 [inline] read_part_sector+0xb8/0x2b0 block/partitions/core.c:723 adfspart_check_ICS+0xa5/0xa40 block/partitions/acorn.c:360 check_partition block/partitions/core.c:142 [inline] blk_add_partitions block/partitions/core.c:590 [inline] bdev_disk_changed+0x7ba/0x1550 block/partitions/core.c:694 blkdev_get_whole+0x2e5/0x480 block/bdev.c:764 bdev_open+0x31e/0xcc0 block/bdev.c:973 blkdev_open+0x485/0x620 block/fops.c:697 do_dentry_open+0x83d/0x13e0 fs/open.c:949 vfs_open+0x3b/0x350 fs/open.c:1081 do_open fs/namei.c:4671 [inline] path_openat+0x2e43/0x38a0 fs/namei.c:4830 do_file_open+0x23e/0x4a0 fs/namei.c:4859 do_sys_openat2+0x113/0x200 fs/open.c:1366 do_sys_open fs/open.c:1372 [inline] __do_sys_openat fs/open.c:1388 [inline] __se_sys_openat fs/open.c:1383 [inline] __x64_sys_openat+0x138/0x170 fs/open.c:1383 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #4 (&cmd->lock){+.+.}-{4:4}: __mutex_lock_common kernel/locking/rtmutex_api.c:533 [inline] mutex_lock_nested+0x5a/0x1d0 kernel/locking/rtmutex_api.c:552 nbd_queue_rq+0xc6/0x1100 drivers/block/nbd.c:1199 blk_mq_dispatch_rq_list+0xa77/0x1910 block/blk-mq.c:2148 __blk_mq_do_dispatch_sched block/blk-mq-sched.c:168 [inline] blk_mq_do_dispatch_sched block/blk-mq-sched.c:182 [inline] __blk_mq_sched_dispatch_requests+0xddb/0x1610 block/blk-mq-sched.c:307 blk_mq_sched_dispatch_requests+0xda/0x1a0 block/blk-mq-sched.c:329 blk_mq_run_hw_queue+0x368/0x520 block/blk-mq.c:2386 blk_mq_dispatch_list+0xd1f/0xe20 include/linux/spinlock_rt.h:-1 blk_mq_flush_plug_list+0x48d/0x570 block/blk-mq.c:2997 __blk_flush_plug+0x3ed/0x4d0 block/blk-core.c:1230 blk_finish_plug block/blk-core.c:1257 [inline] __submit_bio+0x28d/0x580 block/blk-core.c:649 __submit_bio_noacct_mq block/blk-core.c:722 [inline] submit_bio_noacct_nocheck+0x2f4/0xa70 block/blk-core.c:753 submit_bh fs/buffer.c:2826 [inline] block_read_full_folio+0x599/0x830 fs/buffer.c:2444 filemap_read_folio+0x137/0x3b0 mm/filemap.c:2501 do_read_cache_folio+0x2bf/0x560 mm/filemap.c:4101 read_mapping_folio include/linux/pagemap.h:1028 [inline] read_part_sector+0xb8/0x2b0 block/partitions/core.c:723 adfspart_check_ICS+0xa5/0xa40 block/partitions/acorn.c:360 check_partition block/partitions/core.c:142 [inline] blk_add_partitions block/partitions/core.c:590 [inline] bdev_disk_changed+0x7ba/0x1550 block/partitions/core.c:694 blkdev_get_whole+0x2e5/0x480 block/bdev.c:764 bdev_open+0x31e/0xcc0 block/bdev.c:973 blkdev_open+0x485/0x620 block/fops.c:697 do_dentry_open+0x83d/0x13e0 fs/open.c:949 vfs_open+0x3b/0x350 fs/open.c:1081 do_open fs/namei.c:4671 [inline] path_openat+0x2e43/0x38a0 fs/namei.c:4830 do_file_open+0x23e/0x4a0 fs/namei.c:4859 do_sys_openat2+0x113/0x200 fs/open.c:1366 do_sys_open fs/open.c:1372 [inline] __do_sys_openat fs/open.c:1388 [inline] __se_sys_openat fs/open.c:1383 [inline] __x64_sys_openat+0x138/0x170 fs/open.c:1383 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #3 (set->srcu){.+.+}-{0:0}: srcu_lock_sync include/linux/srcu.h:199 [inline] __synchronize_srcu+0xca/0x3e0 kernel/rcu/srcutree.c:1505 elevator_switch+0x1e8/0x7a0 block/elevator.c:576 elevator_change+0x2cc/0x450 block/elevator.c:681 elevator_set_default+0x36c/0x430 block/elevator.c:754 blk_register_queue+0x366/0x430 block/blk-sysfs.c:946 __add_disk+0x677/0xd50 block/genhd.c:528 add_disk_fwnode+0xfb/0x480 block/genhd.c:597 add_disk include/linux/blkdev.h:785 [inline] nbd_dev_add+0x72c/0xb50 drivers/block/nbd.c:1984 nbd_init+0x168/0x1f0 drivers/block/nbd.c:2692 do_one_initcall+0x250/0x8d0 init/main.c:1382 do_initcall_level+0x104/0x190 init/main.c:1444 do_initcalls+0x59/0xa0 init/main.c:1460 kernel_init_freeable+0x2a6/0x3e0 init/main.c:1692 kernel_init+0x1d/0x1d0 init/main.c:1582 ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 -> #2 (&q->elevator_lock){+.+.}-{4:4}: __mutex_lock_common kernel/locking/rtmutex_api.c:533 [inline] mutex_lock_nested+0x5a/0x1d0 kernel/locking/rtmutex_api.c:552 elevator_change+0x1b3/0x450 block/elevator.c:679 elevator_set_none+0xb5/0x140 block/elevator.c:769 blk_mq_elv_switch_none block/blk-mq.c:5110 [inline] __blk_mq_update_nr_hw_queues block/blk-mq.c:5155 [inline] blk_mq_update_nr_hw_queues+0x607/0x1a80 block/blk-mq.c:5220 nbd_start_device+0x17f/0xb20 drivers/block/nbd.c:1489 nbd_start_device_ioctl drivers/block/nbd.c:1548 [inline] __nbd_ioctl drivers/block/nbd.c:1623 [inline] nbd_ioctl+0x57b/0xe40 drivers/block/nbd.c:1663 blkdev_ioctl+0x5e6/0x750 block/ioctl.c:804 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:597 [inline] __se_sys_ioctl+0xff/0x170 fs/ioctl.c:583 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #1 (&q->q_usage_counter(io)#53){++++}-{0:0}: blk_alloc_queue+0x54e/0x690 block/blk-core.c:461 blk_mq_alloc_queue block/blk-mq.c:4429 [inline] __blk_mq_alloc_disk+0x197/0x390 block/blk-mq.c:4476 nbd_dev_add+0x499/0xb50 drivers/block/nbd.c:1954 nbd_init+0x168/0x1f0 drivers/block/nbd.c:2692 do_one_initcall+0x250/0x8d0 init/main.c:1382 do_initcall_level+0x104/0x190 init/main.c:1444 do_initcalls+0x59/0xa0 init/main.c:1460 kernel_init_freeable+0x2a6/0x3e0 init/main.c:1692 kernel_init+0x1d/0x1d0 init/main.c:1582 ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 -> #0 (fs_reclaim){+.+.}-{0:0}: check_prev_add kernel/locking/lockdep.c:3165 [inline] check_prevs_add kernel/locking/lockdep.c:3284 [inline] validate_chain kernel/locking/lockdep.c:3908 [inline] __lock_acquire+0x15a5/0x2cf0 kernel/locking/lockdep.c:5237 lock_acquire+0xf0/0x2e0 kernel/locking/lockdep.c:5868 __fs_reclaim_acquire mm/page_alloc.c:4348 [inline] fs_reclaim_acquire+0x71/0x100 mm/page_alloc.c:4362 might_alloc include/linux/sched/mm.h:317 [inline] slab_pre_alloc_hook mm/slub.c:4493 [inline] slab_alloc_node mm/slub.c:4846 [inline] kmem_cache_alloc_node_noprof+0x4b/0x6e0 mm/slub.c:4921 __alloc_skb+0x1d0/0x7d0 net/core/skbuff.c:702 alloc_skb include/linux/skbuff.h:1383 [inline] alloc_uevent_skb+0x7d/0x230 lib/kobject_uevent.c:289 uevent_net_broadcast_untagged lib/kobject_uevent.c:326 [inline] kobject_uevent_net_broadcast+0x2fd/0x560 lib/kobject_uevent.c:410 kobject_uevent_env+0x55f/0x9e0 lib/kobject_uevent.c:608 nbd_config_put+0x14e/0x580 drivers/block/nbd.c:1440 nbd_release+0x101/0x140 drivers/block/nbd.c:1756 bdev_release+0x541/0x660 block/bdev.c:-1 blkdev_release+0x15/0x20 block/fops.c:705 __fput+0x461/0xa90 fs/file_table.c:469 fput_close_sync+0x11f/0x240 fs/file_table.c:574 __do_sys_close fs/open.c:1509 [inline] __se_sys_close fs/open.c:1494 [inline] __x64_sys_close+0x7e/0x110 fs/open.c:1494 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f other info that might help us debug this: Chain exists of: fs_reclaim --> cpuhp_state-up --> uevent_sock_mutex Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(uevent_sock_mutex); lock(cpuhp_state-up); lock(uevent_sock_mutex); lock(fs_reclaim); *** DEADLOCK *** 3 locks held by udevd/17714: #0: ffff8880265394c8 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_release+0x1af/0x660 block/bdev.c:1144 #1: ffff888026357a48 (&nbd->config_lock){+.+.}-{4:4}, at: refcount_dec_and_mutex_lock+0x30/0xa0 lib/refcount.c:118 #2: ffffffff8f50f6f8 (uevent_sock_mutex){+.+.}-{4:4}, at: uevent_net_broadcast_untagged lib/kobject_uevent.c:317 [inline] #2: ffffffff8f50f6f8 (uevent_sock_mutex){+.+.}-{4:4}, at: kobject_uevent_net_broadcast+0x281/0x560 lib/kobject_uevent.c:410 stack backtrace: CPU: 1 UID: 0 PID: 17714 Comm: udevd Tainted: G L syzkaller #0 PREEMPT_{RT,(full)} Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/27/2026 Call Trace: dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120 print_circular_bug+0x2e1/0x300 kernel/locking/lockdep.c:2043 check_noncircular+0x12e/0x150 kernel/locking/lockdep.c:2175 check_prev_add kernel/locking/lockdep.c:3165 [inline] check_prevs_add kernel/locking/lockdep.c:3284 [inline] validate_chain kernel/locking/lockdep.c:3908 [inline] __lock_acquire+0x15a5/0x2cf0 kernel/locking/lockdep.c:5237 lock_acquire+0xf0/0x2e0 kernel/locking/lockdep.c:5868 __fs_reclaim_acquire mm/page_alloc.c:4348 [inline] fs_reclaim_acquire+0x71/0x100 mm/page_alloc.c:4362 might_alloc include/linux/sched/mm.h:317 [inline] slab_pre_alloc_hook mm/slub.c:4493 [inline] slab_alloc_node mm/slub.c:4846 [inline] kmem_cache_alloc_node_noprof+0x4b/0x6e0 mm/slub.c:4921 __alloc_skb+0x1d0/0x7d0 net/core/skbuff.c:702 alloc_skb include/linux/skbuff.h:1383 [inline] alloc_uevent_skb+0x7d/0x230 lib/kobject_uevent.c:289 uevent_net_broadcast_untagged lib/kobject_uevent.c:326 [inline] kobject_uevent_net_broadcast+0x2fd/0x560 lib/kobject_uevent.c:410 kobject_uevent_env+0x55f/0x9e0 lib/kobject_uevent.c:608 nbd_config_put+0x14e/0x580 drivers/block/nbd.c:1440 nbd_release+0x101/0x140 drivers/block/nbd.c:1756 bdev_release+0x541/0x660 block/bdev.c:-1 blkdev_release+0x15/0x20 block/fops.c:705 __fput+0x461/0xa90 fs/file_table.c:469 fput_close_sync+0x11f/0x240 fs/file_table.c:574 __do_sys_close fs/open.c:1509 [inline] __se_sys_close fs/open.c:1494 [inline] __x64_sys_close+0x7e/0x110 fs/open.c:1494 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f8673677407 Code: 48 89 fa 4c 89 df e8 38 aa 00 00 8b 93 08 03 00 00 59 5e 48 83 f8 fc 74 1a 5b c3 0f 1f 84 00 00 00 00 00 48 8b 44 24 10 0f 05 <5b> c3 0f 1f 80 00 00 00 00 83 e2 39 83 fa 08 75 de e8 23 ff ff ff RSP: 002b:00007ffde0577e70 EFLAGS: 00000202 ORIG_RAX: 0000000000000003 RAX: ffffffffffffffda RBX: 00007f8673589880 RCX: 00007f8673677407 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000008 RBP: 00007f86735896e8 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000002 R13: 0000560ef6049190 R14: 0000000000000008 R15: 0000560ef607f370 --- 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@googlegroups.com. 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