From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-oo1-f69.google.com (mail-oo1-f69.google.com [209.85.161.69]) (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 BEC18352030 for ; Mon, 14 Sep 2026 23:00:30 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.161.69 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789426832; cv=none; b=rA1cQjEyOk4AhFpmuFB1zxRiKJQdxx8zm7KHa80cSHm0pFuNRr7Ct0pus/UqW1Xzd0GoE8GOmLB/Av8P08xyw+ZFJr1M5aqxUpJOJnRUPbytdbVsCI2du4bn7XDNFJz+3smWpxTMJq4rumTOehvrrnH/d04TsfJpmLEZNfCidaE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789426832; c=relaxed/simple; bh=Uvda3mpDZ+Q/k7LZ/3pQQ7KyTaZcRTOLWlF3hmPQjjE=; h=MIME-Version:Date:In-Reply-To:Message-ID:Subject:From:To: Content-Type; 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2002:a05:6820:4c02:b0:6be:46f4:2908 with SMTP id 006d021491bc7-6c544dad007mr2996077eaf.55.1789426829545; Mon, 14 Sep 2026 16:00:29 -0700 (PDT) Date: Mon, 14 Sep 2026 16:00:29 -0700 In-Reply-To: <6a6d3cbd.6ce73036.24301b.000d.GAE@google.com> X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <6aa87c8d.4c28b7d0.c1bba.0020.GAE@google.com> Subject: Re: [syzbot] [raid?] possible deadlock in blk_probe_dev From: syzbot To: axboe@kernel.dk, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, linux-raid@vger.kernel.org, song@kernel.org, syzkaller-bugs@googlegroups.com, yukuai@fnnas.com Content-Type: text/plain; charset="UTF-8" syzbot has found a reproducer for the following issue on: HEAD commit: 704340f1cd0d Merge tag 'x86_urgent_for_7.3-rc4' of git://g.. git tree: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git console output: https://syzkaller.appspot.com/x/log.txt?x=12ff9905580000 kernel config: https://syzkaller.appspot.com/x/.config?x=8c5c3949d762a91f dashboard link: https://syzkaller.appspot.com/bug?extid=68e1f51046d68329940f compiler: gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=11a0bc8e580000 IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+68e1f51046d68329940f@syzkaller.appspotmail.com ====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Not tainted ------------------------------------------------------ syz-executor197/4337 is trying to acquire lock: ffff888023113d40 ((wq_completion)md_misc){+.+.}-{0:0}, at: touch_wq_lockdep_map+0x9c/0x1c0 kernel/workqueue.c:4111 but task is already holding lock: ffffffff8f9b98e0 (major_names_lock){+.+.}-{4:4}, at: blk_probe_dev+0x28/0x1e0 block/genhd.c:885 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #3 (major_names_lock){+.+.}-{4:4}: lock_acquire kernel/locking/lockdep.c:5942 [inline] lock_acquire+0x1d1/0x380 kernel/locking/lockdep.c:5899 __mutex_lock_common kernel/locking/mutex.c:646 [inline] __mutex_lock+0x1a4/0x1bd0 kernel/locking/mutex.c:821 blk_probe_dev+0x28/0x1e0 block/genhd.c:885 blk_request_module+0x16/0xc0 block/genhd.c:901 blkdev_get_no_open+0x9b/0xf0 block/bdev.c:870 bdev_file_open_by_dev block/bdev.c:1091 [inline] bdev_file_open_by_dev+0x70/0x210 block/bdev.c:1079 md_import_device+0x120/0x360 drivers/md/md.c:3847 md_add_new_disk+0xdbf/0x1820 drivers/md/md.c:7656 md_ioctl+0x2bec/0x36d0 drivers/md/md.c:8499 blkdev_ioctl+0x5ad/0x6f0 block/ioctl.c:798 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:61 [inline] do_syscall_64+0x123/0x790 arch/x86/entry/syscall_64.c:84 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #2 (&mddev->reconfig_mutex){+.+.}-{4:4}: lock_acquire kernel/locking/lockdep.c:5942 [inline] lock_acquire+0x1d1/0x380 kernel/locking/lockdep.c:5899 __mutex_lock_common kernel/locking/mutex.c:646 [inline] __mutex_lock+0x1a4/0x1bd0 kernel/locking/mutex.c:821 mddev_lock_nointr drivers/md/md.h:734 [inline] md_start_sync+0xc4/0xea0 drivers/md/md.c:10275 process_one_work+0xac7/0x1b10 kernel/workqueue.c:3396 process_scheduled_works kernel/workqueue.c:3479 [inline] worker_thread+0x5ef/0xe50 kernel/workqueue.c:3560 kthread+0x373/0x450 kernel/kthread.c:436 ret_from_fork+0x730/0xd60 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 -> #1 ((work_completion)(&mddev->sync_work)){+.+.}-{0:0}: lock_acquire kernel/locking/lockdep.c:5942 [inline] lock_acquire+0x1d1/0x380 kernel/locking/lockdep.c:5899 process_one_work+0xa32/0x1b10 kernel/workqueue.c:3372 process_scheduled_works kernel/workqueue.c:3479 [inline] worker_thread+0x5ef/0xe50 kernel/workqueue.c:3560 kthread+0x373/0x450 kernel/kthread.c:436 ret_from_fork+0x730/0xd60 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 -> #0 ((wq_completion)md_misc){+.+.}-{0:0}: check_prev_add+0xeb/0xe60 kernel/locking/lockdep.c:3209 check_prevs_add kernel/locking/lockdep.c:3328 [inline] validate_chain kernel/locking/lockdep.c:3952 [inline] __lock_acquire+0x1528/0x1f40 kernel/locking/lockdep.c:5288 lock_acquire kernel/locking/lockdep.c:5942 [inline] lock_acquire+0x1d1/0x380 kernel/locking/lockdep.c:5899 touch_wq_lockdep_map+0xad/0x1c0 kernel/workqueue.c:4111 __flush_workqueue+0x131/0x1200 kernel/workqueue.c:4153 md_alloc+0x30/0x10a0 drivers/md/md.c:6334 md_alloc_and_put drivers/md/md.c:6423 [inline] md_probe drivers/md/md.c:6439 [inline] md_probe+0x73/0xf0 drivers/md/md.c:6434 blk_probe_dev+0x149/0x1e0 block/genhd.c:888 blk_request_module+0x16/0xc0 block/genhd.c:901 blkdev_get_no_open+0x9b/0xf0 block/bdev.c:870 blkdev_open+0x141/0x4f0 block/fops.c:665 do_dentry_open+0x6ab/0x14d0 fs/open.c:996 vfs_open+0x82/0x3f0 fs/open.c:1101 do_open fs/namei.c:4837 [inline] path_openat+0x19fa/0x2440 fs/namei.c:5000 do_file_open+0x20e/0x430 fs/namei.c:5029 do_sys_openat2+0x10f/0x1e0 fs/open.c:1417 do_sys_open fs/open.c:1423 [inline] __do_sys_openat fs/open.c:1439 [inline] __se_sys_openat fs/open.c:1434 [inline] __x64_sys_openat+0x12d/0x210 fs/open.c:1434 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline] do_syscall_64+0x123/0x790 arch/x86/entry/syscall_64.c:84 entry_SYSCALL_64_after_hwframe+0x77/0x7f other info that might help us debug this: Chain exists of: (wq_completion)md_misc --> &mddev->reconfig_mutex --> major_names_lock Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(major_names_lock); lock(&mddev->reconfig_mutex); lock(major_names_lock); lock((wq_completion)md_misc); *** DEADLOCK *** locks held by syz-executor197/4337: 1, last CPU#2: #0: ffffffff8f9b98e0 (major_names_lock){+.+.}-{4:4}, at: blk_probe_dev+0x28/0x1e0 block/genhd.c:885 stack backtrace: CPU: 2 UID: 0 PID: 4337 Comm: syz-executor197 Not tainted syzkaller #0 PREEMPT(full) Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120 print_circular_bug.cold+0x178/0x1be kernel/locking/lockdep.c:2087 check_noncircular+0x146/0x160 kernel/locking/lockdep.c:2219 check_prev_add+0xeb/0xe60 kernel/locking/lockdep.c:3209 check_prevs_add kernel/locking/lockdep.c:3328 [inline] validate_chain kernel/locking/lockdep.c:3952 [inline] __lock_acquire+0x1528/0x1f40 kernel/locking/lockdep.c:5288 lock_acquire kernel/locking/lockdep.c:5942 [inline] lock_acquire+0x1d1/0x380 kernel/locking/lockdep.c:5899 touch_wq_lockdep_map+0xad/0x1c0 kernel/workqueue.c:4111 __flush_workqueue+0x131/0x1200 kernel/workqueue.c:4153 md_alloc+0x30/0x10a0 drivers/md/md.c:6334 md_alloc_and_put drivers/md/md.c:6423 [inline] md_probe drivers/md/md.c:6439 [inline] md_probe+0x73/0xf0 drivers/md/md.c:6434 blk_probe_dev+0x149/0x1e0 block/genhd.c:888 blk_request_module+0x16/0xc0 block/genhd.c:901 blkdev_get_no_open+0x9b/0xf0 block/bdev.c:870 blkdev_open+0x141/0x4f0 block/fops.c:665 do_dentry_open+0x6ab/0x14d0 fs/open.c:996 vfs_open+0x82/0x3f0 fs/open.c:1101 do_open fs/namei.c:4837 [inline] path_openat+0x19fa/0x2440 fs/namei.c:5000 do_file_open+0x20e/0x430 fs/namei.c:5029 do_sys_openat2+0x10f/0x1e0 fs/open.c:1417 do_sys_open fs/open.c:1423 [inline] __do_sys_openat fs/open.c:1439 [inline] __se_sys_openat fs/open.c:1434 [inline] __x64_sys_openat+0x12d/0x210 fs/open.c:1434 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline] do_syscall_64+0x123/0x790 arch/x86/entry/syscall_64.c:84 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fc5b6fe4b37 Code: 48 89 fa 4c 89 df e8 98 1d 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:00007ffd92e81700 EFLAGS: 00000202 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 000055557809b400 RCX: 00007fc5b6fe4b37 RDX: 0000000000000002 RSI: 00007ffd92e81810 RDI: ffffffffffffff9c RBP: 00007ffd92e81810 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000004 R13: 0000000000000005 R14: 00007fc5b7049ca0 R15: 0000000000000002 md: async del_gendisk mode will be removed in future, please upgrade to mdadm-4.5+ block device autoloading is deprecated and will be removed. md: could not open device unknown-block(0,0). md: md_import_device returned -6 md/raid1:md127: not clean -- starting background reconstruction md/raid1:md127: active with 2 out of 2 mirrors md127: detected capacity change from 0 to 20480 md127: detected capacity change from 20480 to 0 md: md127 stopped. --- If you want syzbot to run the reproducer, reply with: #syz test: git://repo/address.git branch-or-commit-hash If you attach or paste a git patch, syzbot will apply it before testing.