From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-oo1-f79.google.com (mail-oo1-f79.google.com [209.85.161.79]) (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 0C8631FFC48 for ; Sat, 25 Apr 2026 02:12:43 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.161.79 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777083166; cv=none; b=mhcHJg/VgnKt81ulHmq3Ae4x4oY6iTC6PukDZ/ULTD6jlIBd6GfImfjV8STroxQNhJggkxQFJiTa+b80QvIwYPuaWZXgGVFt2+ir4ea8JfBgoanq3i6Cfy8ajxLMgtYKPfJj5hKQQaJW4UUD1J72OAbHYGPye7GDJf9XBSmir7s= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777083166; c=relaxed/simple; bh=cSVFK32125zLIa9+xZ5XFWbB/gFy2DTY3wG/K2eIuQg=; h=MIME-Version:Date:Message-ID:Subject:From:To:Content-Type; b=FpTqPNxt16cenjwq10w3SXKgLp+3uDxQpmtrGFoSukfDeuSKKSqij8b2bzBXRPHecfC4R9NnKvPELs0ip9SkSiX5QRoWlBJVr9tfZL0SjLUiPoRqhoMKCfmeHHU2BqK9CLhz4vEBU0RstUmdNhc+t8RWtO2F1JDOZnDhsBtcYAM= 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=209.85.161.79 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-oo1-f79.google.com with SMTP id 006d021491bc7-6948df7c598so13596953eaf.1 for ; Fri, 24 Apr 2026 19:12:43 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1777083163; x=1777687963; h=to:from:subject:message-id:date:mime-version:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=ZB4BZOU7furfeT2KE85DNOaOObbgNs0fZjr2ghrS+qQ=; b=ByxPCcblpL2BS62S6FJ0hZ2TcUldKmM8y7/6pGy914Jnv3neenpr6dNqrE30+afWjA DRiLgLPMdwYcsxV7ZgTbWSR4i0yXOtyqD9ppgI5MjI9ycedvXoxF8JKl0Ti2HUQxwyhG 2qiqYXkc4MpIkGtpR6GElyv1OxTl6dXNwdS6v+Hw2mlYUOUO4BK/LQIyGbH6QBT52r8F 3mFZBeF19egfilF8xclUlkhPyNsqRxnPoisfV5U1NR9rcBxKvIG1cV99Dqj3GD/t1ujd P+zhjQAW/d4DsPBsh4mVX8ho3S1KQwGwq7v5p/+pMK/dkGwmJzdGeeXpWNGRok3UWKwK DWBw== X-Forwarded-Encrypted: i=1; AFNElJ8lnY8OmWm2g9iZZH2A/BqdQ/yUHMDVjmPK2OEPK2s4sxsynx07YPELlTNLuo4X47kJkTmgUz4sRGivPA==@vger.kernel.org X-Gm-Message-State: AOJu0Yx5jNbBt/qwdKiNaeubF8wnTAsbd//5GFq0hjQ2kMqusWwVNQom 1mQwYT0xJzBI1HZOVwRu0aNjP0RuxAkGKT2om/C6l4gt6TfLI0IxAT45rXoF4MU9RwFhI7QYrik iZ1UD7bPUJ+he4FtsRnOJ+jY0tSNOtLoW3EFbaIagmsj/VgucH0a3BI1QJk4= Precedence: bulk X-Mailing-List: linux-block@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Received: by 2002:a05:6820:288a:b0:694:8bbf:e51b with SMTP id 006d021491bc7-6948bbfee00mr8787706eaf.36.1777083163073; Fri, 24 Apr 2026 19:12:43 -0700 (PDT) Date: Fri, 24 Apr 2026 19:12:43 -0700 X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <69ec231b.a00a0220.7773.000d.GAE@google.com> Subject: [syzbot] [block?] possible deadlock in bioset_exit From: syzbot To: axboe@kernel.dk, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com Content-Type: text/plain; charset="UTF-8" Hello, syzbot found the following issue on: HEAD commit: dd6c438c3e64 Merge tag 'vfs-7.1-rc1.fixes' of git://git.ke.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=14efc2ce580000 kernel config: https://syzkaller.appspot.com/x/.config?x=6d74203cd0463a9f dashboard link: https://syzkaller.appspot.com/bug?extid=02b4e6eb8b1460d955a5 compiler: gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44 Unfortunately, I don't have any reproducer for this issue yet. Downloadable assets: disk image: https://storage.googleapis.com/syzbot-assets/8bebdd77187b/disk-dd6c438c.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/2527d5942bbb/vmlinux-dd6c438c.xz kernel image: https://storage.googleapis.com/syzbot-assets/d446b541e2e0/bzImage-dd6c438c.xz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+02b4e6eb8b1460d955a5@syzkaller.appspotmail.com ubi31: attaching mtd0 ====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Tainted: G L ------------------------------------------------------ syz.7.5359/28440 is trying to acquire lock: ffffffff8e9b1780 (fs_reclaim){+.+.}-{0:0}, at: might_alloc include/linux/sched/mm.h:317 [inline] ffffffff8e9b1780 (fs_reclaim){+.+.}-{0:0}, at: slab_pre_alloc_hook mm/slub.c:4520 [inline] ffffffff8e9b1780 (fs_reclaim){+.+.}-{0:0}, at: slab_alloc_node mm/slub.c:4875 [inline] ffffffff8e9b1780 (fs_reclaim){+.+.}-{0:0}, at: kmem_cache_alloc_noprof+0x4c/0x6e0 mm/slub.c:4905 but task is already holding lock: ffffffff8e97f100 (slab_mutex){+.+.}-{4:4}, at: __kmem_cache_create_args+0x44/0x420 mm/slab_common.c:350 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #7 (slab_mutex){+.+.}-{4:4}: __mutex_lock_common kernel/locking/mutex.c:632 [inline] __mutex_lock+0x1a4/0x1b10 kernel/locking/mutex.c:806 kmem_cache_destroy mm/slab_common.c:557 [inline] kmem_cache_destroy+0x59/0x180 mm/slab_common.c:527 bio_put_slab block/bio.c:163 [inline] bioset_exit+0x3b1/0x520 block/bio.c:1907 mddev_destroy drivers/md/md.c:819 [inline] mddev_free drivers/md/md.c:911 [inline] md_free_disk+0x18e/0x210 drivers/md/md.c:8578 disk_release+0x2b2/0x430 block/genhd.c:1311 device_release+0xd2/0x270 drivers/base/core.c:2566 kobject_cleanup lib/kobject.c:689 [inline] kobject_release lib/kobject.c:720 [inline] kref_put include/linux/kref.h:65 [inline] kobject_put+0x1f7/0x640 lib/kobject.c:737 process_one_work+0xa0e/0x1980 kernel/workqueue.c:3302 process_scheduled_works kernel/workqueue.c:3385 [inline] worker_thread+0x5ef/0xe50 kernel/workqueue.c:3466 kthread+0x370/0x450 kernel/kthread.c:436 ret_from_fork+0x72b/0xd50 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 -> #6 (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+0x42/0x170 kernel/cpu.c:490 static_key_slow_inc+0x12/0x30 kernel/jump_label.c:190 nbd_reconnect_socket drivers/block/nbd.c:1342 [inline] nbd_genl_reconfigure+0xd82/0x1a00 drivers/block/nbd.c:2431 genl_family_rcv_msg_doit+0x214/0x300 net/netlink/genetlink.c:1114 genl_family_rcv_msg net/netlink/genetlink.c:1194 [inline] genl_rcv_msg+0x560/0x800 net/netlink/genetlink.c:1209 netlink_rcv_skb+0x159/0x420 net/netlink/af_netlink.c:2550 genl_rcv+0x28/0x40 net/netlink/genetlink.c:1218 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline] netlink_unicast+0x585/0x850 net/netlink/af_netlink.c:1344 netlink_sendmsg+0x8b0/0xda0 net/netlink/af_netlink.c:1894 sock_sendmsg_nosec net/socket.c:787 [inline] __sock_sendmsg net/socket.c:802 [inline] ____sys_sendmsg+0x9e1/0xb70 net/socket.c:2698 ___sys_sendmsg+0x190/0x1e0 net/socket.c:2752 __sys_sendmsg+0x170/0x220 net/socket.c:2784 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x10b/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #5 (&nsock->tx_lock){+.+.}-{4:4}: __mutex_lock_common kernel/locking/mutex.c:632 [inline] __mutex_lock+0x1a4/0x1b10 kernel/locking/mutex.c:806 nbd_handle_cmd drivers/block/nbd.c:1143 [inline] nbd_queue_rq+0x428/0x1080 drivers/block/nbd.c:1207 blk_mq_dispatch_rq_list+0x422/0x1e70 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+0xcea/0x1620 block/blk-mq-sched.c:307 blk_mq_sched_dispatch_requests+0xd7/0x1c0 block/blk-mq-sched.c:329 blk_mq_run_hw_queue+0x23c/0x670 block/blk-mq.c:2386 blk_mq_dispatch_list+0x51d/0x1360 block/blk-mq.c:2949 blk_mq_flush_plug_list block/blk-mq.c:2997 [inline] blk_mq_flush_plug_list+0x130/0x600 block/blk-mq.c:2969 __blk_flush_plug+0x2c4/0x4b0 block/blk-core.c:1230 blk_finish_plug block/blk-core.c:1257 [inline] __submit_bio+0x584/0x6c0 block/blk-core.c:649 __submit_bio_noacct_mq block/blk-core.c:722 [inline] submit_bio_noacct_nocheck+0x543/0xbf0 block/blk-core.c:753 submit_bio_noacct+0xd18/0x2000 block/blk-core.c:884 blk_crypto_submit_bio include/linux/blk-crypto.h:203 [inline] submit_bh_wbc+0x681/0x890 fs/buffer.c:2737 submit_bh fs/buffer.c:2742 [inline] block_read_full_folio+0x4c8/0x8e0 fs/buffer.c:2358 filemap_read_folio+0xfc/0x3b0 mm/filemap.c:2502 do_read_cache_folio+0x2d7/0x6b0 mm/filemap.c:4107 read_mapping_folio include/linux/pagemap.h:1017 [inline] read_part_sector+0xd1/0x370 block/partitions/core.c:724 adfspart_check_ICS+0x91/0x7d0 block/partitions/acorn.c:356 check_partition block/partitions/core.c:143 [inline] blk_add_partitions block/partitions/core.c:591 [inline] bdev_disk_changed+0x7a3/0x1250 block/partitions/core.c:695 blkdev_get_whole+0x187/0x290 block/bdev.c:756 bdev_open+0x2c7/0xe40 block/bdev.c:965 blkdev_open+0x34e/0x4f0 block/fops.c:697 do_dentry_open+0x6d8/0x1660 fs/open.c:947 vfs_open+0x82/0x3f0 fs/open.c:1079 do_open fs/namei.c:4699 [inline] path_openat+0x208c/0x31a0 fs/namei.c:4858 do_file_open+0x20e/0x430 fs/namei.c:4887 do_sys_openat2+0x10d/0x1e0 fs/open.c:1364 do_sys_open fs/open.c:1370 [inline] __do_sys_openat fs/open.c:1386 [inline] __se_sys_openat fs/open.c:1381 [inline] __x64_sys_openat+0x12d/0x210 fs/open.c:1381 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x10b/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/mutex.c:632 [inline] __mutex_lock+0x1a4/0x1b10 kernel/locking/mutex.c:806 nbd_queue_rq+0xba/0x1080 drivers/block/nbd.c:1199 blk_mq_dispatch_rq_list+0x422/0x1e70 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+0xcea/0x1620 block/blk-mq-sched.c:307 blk_mq_sched_dispatch_requests+0xd7/0x1c0 block/blk-mq-sched.c:329 blk_mq_run_hw_queue+0x23c/0x670 block/blk-mq.c:2386 blk_mq_dispatch_list+0x51d/0x1360 block/blk-mq.c:2949 blk_mq_flush_plug_list block/blk-mq.c:2997 [inline] blk_mq_flush_plug_list+0x130/0x600 block/blk-mq.c:2969 __blk_flush_plug+0x2c4/0x4b0 block/blk-core.c:1230 blk_finish_plug block/blk-core.c:1257 [inline] __submit_bio+0x584/0x6c0 block/blk-core.c:649 __submit_bio_noacct_mq block/blk-core.c:722 [inline] submit_bio_noacct_nocheck+0x543/0xbf0 block/blk-core.c:753 submit_bio_noacct+0xd18/0x2000 block/blk-core.c:884 blk_crypto_submit_bio include/linux/blk-crypto.h:203 [inline] submit_bh_wbc+0x681/0x890 fs/buffer.c:2737 submit_bh fs/buffer.c:2742 [inline] block_read_full_folio+0x4c8/0x8e0 fs/buffer.c:2358 filemap_read_folio+0xfc/0x3b0 mm/filemap.c:2502 do_read_cache_folio+0x2d7/0x6b0 mm/filemap.c:4107 read_mapping_folio include/linux/pagemap.h:1017 [inline] read_part_sector+0xd1/0x370 block/partitions/core.c:724 adfspart_check_ICS+0x91/0x7d0 block/partitions/acorn.c:356 check_partition block/partitions/core.c:143 [inline] blk_add_partitions block/partitions/core.c:591 [inline] bdev_disk_changed+0x7a3/0x1250 block/partitions/core.c:695 blkdev_get_whole+0x187/0x290 block/bdev.c:756 bdev_open+0x2c7/0xe40 block/bdev.c:965 blkdev_open+0x34e/0x4f0 block/fops.c:697 do_dentry_open+0x6d8/0x1660 fs/open.c:947 vfs_open+0x82/0x3f0 fs/open.c:1079 do_open fs/namei.c:4699 [inline] path_openat+0x208c/0x31a0 fs/namei.c:4858 do_file_open+0x20e/0x430 fs/namei.c:4887 do_sys_openat2+0x10d/0x1e0 fs/open.c:1364 do_sys_open fs/open.c:1370 [inline] __do_sys_openat fs/open.c:1386 [inline] __se_sys_openat fs/open.c:1381 [inline] __x64_sys_openat+0x12d/0x210 fs/open.c:1381 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x10b/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+0xa2/0x300 kernel/rcu/srcutree.c:1481 blk_mq_wait_quiesce_done block/blk-mq.c:284 [inline] blk_mq_wait_quiesce_done block/blk-mq.c:281 [inline] blk_mq_quiesce_queue block/blk-mq.c:304 [inline] blk_mq_quiesce_queue+0x149/0x1c0 block/blk-mq.c:299 elevator_switch+0x17b/0x7e0 block/elevator.c:576 elevator_change+0x352/0x530 block/elevator.c:681 elevator_set_default+0x29e/0x360 block/elevator.c:754 blk_register_queue+0x48e/0x630 block/blk-sysfs.c:987 __add_disk+0x73f/0xe40 block/genhd.c:528 add_disk_fwnode+0x118/0x5c0 block/genhd.c:597 add_disk include/linux/blkdev.h:794 [inline] nbd_dev_add+0x77a/0xb10 drivers/block/nbd.c:1984 nbd_init+0x291/0x2b0 drivers/block/nbd.c:2692 do_one_initcall+0x121/0x750 init/main.c:1392 do_initcall_level init/main.c:1454 [inline] do_initcalls init/main.c:1470 [inline] do_basic_setup init/main.c:1490 [inline] kernel_init_freeable+0x6ea/0x7b0 init/main.c:1703 kernel_init+0x1f/0x1e0 init/main.c:1593 ret_from_fork+0x72b/0xd50 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/mutex.c:632 [inline] __mutex_lock+0x1a4/0x1b10 kernel/locking/mutex.c:806 elevator_change+0x1bc/0x530 block/elevator.c:679 elevator_set_none+0x92/0xf0 block/elevator.c:769 blk_mq_elv_switch_none block/blk-mq.c:5131 [inline] __blk_mq_update_nr_hw_queues block/blk-mq.c:5176 [inline] blk_mq_update_nr_hw_queues+0x4c1/0x15f0 block/blk-mq.c:5241 nbd_start_device+0x1a6/0xbd0 drivers/block/nbd.c:1489 nbd_genl_connect+0xff2/0x1a40 drivers/block/nbd.c:2239 genl_family_rcv_msg_doit+0x214/0x300 net/netlink/genetlink.c:1114 genl_family_rcv_msg net/netlink/genetlink.c:1194 [inline] genl_rcv_msg+0x560/0x800 net/netlink/genetlink.c:1209 netlink_rcv_skb+0x159/0x420 net/netlink/af_netlink.c:2550 genl_rcv+0x28/0x40 net/netlink/genetlink.c:1218 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline] netlink_unicast+0x585/0x850 net/netlink/af_netlink.c:1344 netlink_sendmsg+0x8b0/0xda0 net/netlink/af_netlink.c:1894 sock_sendmsg_nosec net/socket.c:787 [inline] __sock_sendmsg net/socket.c:802 [inline] ____sys_sendmsg+0x9e1/0xb70 net/socket.c:2698 ___sys_sendmsg+0x190/0x1e0 net/socket.c:2752 __sys_sendmsg+0x170/0x220 net/socket.c:2784 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x10b/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #1 (&q->q_usage_counter(io)#50){++++}-{0:0}: blk_alloc_queue+0x610/0x790 block/blk-core.c:461 blk_mq_alloc_queue+0x174/0x290 block/blk-mq.c:4450 __blk_mq_alloc_disk+0x29/0x120 block/blk-mq.c:4497 nbd_dev_add+0x492/0xb10 drivers/block/nbd.c:1954 nbd_init+0x291/0x2b0 drivers/block/nbd.c:2692 do_one_initcall+0x121/0x750 init/main.c:1392 do_initcall_level init/main.c:1454 [inline] do_initcalls init/main.c:1470 [inline] do_basic_setup init/main.c:1490 [inline] kernel_init_freeable+0x6ea/0x7b0 init/main.c:1703 kernel_init+0x1f/0x1e0 init/main.c:1593 ret_from_fork+0x72b/0xd50 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+0x14b8/0x2630 kernel/locking/lockdep.c:5237 lock_acquire kernel/locking/lockdep.c:5868 [inline] lock_acquire+0x1b1/0x370 kernel/locking/lockdep.c:5825 __fs_reclaim_acquire mm/page_alloc.c:4325 [inline] fs_reclaim_acquire+0xc4/0x100 mm/page_alloc.c:4339 might_alloc include/linux/sched/mm.h:317 [inline] slab_pre_alloc_hook mm/slub.c:4520 [inline] slab_alloc_node mm/slub.c:4875 [inline] kmem_cache_alloc_noprof+0x4c/0x6e0 mm/slub.c:4905 create_cache mm/slab_common.c:249 [inline] __kmem_cache_create_args+0x366/0x420 mm/slab_common.c:380 __kmem_cache_create include/linux/slab.h:390 [inline] alloc_ai drivers/mtd/ubi/attach.c:1464 [inline] ubi_attach+0x32a/0x4d30 drivers/mtd/ubi/attach.c:1560 ubi_attach_mtd_dev+0x139f/0x32a0 drivers/mtd/ubi/build.c:1004 ctrl_cdev_ioctl+0x36a/0x400 drivers/mtd/ubi/cdev.c:1113 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:597 [inline] __se_sys_ioctl fs/ioctl.c:583 [inline] __x64_sys_ioctl+0x18e/0x210 fs/ioctl.c:583 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x10b/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 --> cpu_hotplug_lock --> slab_mutex Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(slab_mutex); lock(cpu_hotplug_lock); lock(slab_mutex); lock(fs_reclaim); *** DEADLOCK *** 2 locks held by syz.7.5359/28440: #0: ffffffff8f930b20 (ubi_devices_mutex){+.+.}-{4:4}, at: ctrl_cdev_ioctl+0x323/0x400 drivers/mtd/ubi/cdev.c:1112 #1: ffffffff8e97f100 (slab_mutex){+.+.}-{4:4}, at: __kmem_cache_create_args+0x44/0x420 mm/slab_common.c:350 stack backtrace: CPU: 1 UID: 0 PID: 28440 Comm: syz.7.5359 Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026 Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120 print_circular_bug.cold+0x178/0x1c7 kernel/locking/lockdep.c:2043 check_noncircular+0x146/0x160 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+0x14b8/0x2630 kernel/locking/lockdep.c:5237 lock_acquire kernel/locking/lockdep.c:5868 [inline] lock_acquire+0x1b1/0x370 kernel/locking/lockdep.c:5825 __fs_reclaim_acquire mm/page_alloc.c:4325 [inline] fs_reclaim_acquire+0xc4/0x100 mm/page_alloc.c:4339 might_alloc include/linux/sched/mm.h:317 [inline] slab_pre_alloc_hook mm/slub.c:4520 [inline] slab_alloc_node mm/slub.c:4875 [inline] kmem_cache_alloc_noprof+0x4c/0x6e0 mm/slub.c:4905 create_cache mm/slab_common.c:249 [inline] __kmem_cache_create_args+0x366/0x420 mm/slab_common.c:380 __kmem_cache_create include/linux/slab.h:390 [inline] alloc_ai drivers/mtd/ubi/attach.c:1464 [inline] ubi_attach+0x32a/0x4d30 drivers/mtd/ubi/attach.c:1560 ubi_attach_mtd_dev+0x139f/0x32a0 drivers/mtd/ubi/build.c:1004 ctrl_cdev_ioctl+0x36a/0x400 drivers/mtd/ubi/cdev.c:1113 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:597 [inline] __se_sys_ioctl fs/ioctl.c:583 [inline] __x64_sys_ioctl+0x18e/0x210 fs/ioctl.c:583 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x10b/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f5ceb79cdd9 Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f5cec650028 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007f5ceba16270 RCX: 00007f5ceb79cdd9 RDX: 0000200000000440 RSI: 0000000040186f40 RDI: 0000000000000008 RBP: 00007f5ceb832d69 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f5ceba16308 R14: 00007f5ceba16270 R15: 00007ffca1349ce8 ubi31: scanning is finished ubi31: empty MTD device detected ubi31 error: ubi_attach_mtd_dev: cannot spawn "ubi_bgt31d", error -4 --- 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