From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-il1-f208.google.com (mail-il1-f208.google.com [209.85.166.208]) (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 9E0814690 for ; Thu, 31 Jul 2025 02:14:36 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.166.208 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1753928078; cv=none; b=HKJd9cTTOFTgZ/UpIW/UEtuaSaZSL8xFj6FNt0rmsZjiSX+uiCtGRdMafmXEpzxvo4RAZjodcOIcSHj5MB5fHmI6JKqoFH+xbFKVBA9DDGubnHTt4725Ye1oNcPKnKMZjOvZUtLQz2kr0t2t6HHkm26Abfwi9rq8TLh8KaSnT5g= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1753928078; c=relaxed/simple; bh=PtdtWbfSwsTFIdvQnjmV9oEGOciY0JSHBJVRlxzGeOw=; h=MIME-Version:Date:Message-ID:Subject:From:To:Content-Type; b=anw91LsIuRWD17yZkmA50xCoZFmPK3okDnqjAYimd92kkkWEhzkz5jlJCbDUflO/os9P6NJIvSkx1IavoBuWmmSlGeN2h1HUMxJ/ifiRJYxQX9s12LeYzKNcCpwtIYfaEi9BjTsaaNGdMjWd2RJ6n4A9wxVlXfwyb875Dv4+VV4= 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=209.85.166.208 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-il1-f208.google.com with SMTP id e9e14a558f8ab-3e3d310b012so6976665ab.3 for ; Wed, 30 Jul 2025 19:14:36 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1753928076; x=1754532876; h=to:from:subject:message-id:date:mime-version:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=v8LN82KfcOn/0r6hArwrNITctrGhPFAps37niPBX6GA=; b=AEeX1PYi8DWlME/BEHFEPSWzWd6EGM908auZPHux+HEEUTEzoq3pom+759sh4MNcIq VtRhtvm5WIufI5hbWAakG2bIzl0u9LKuZ6RfYTD2+fzlbMrC44a0Wvfy/jeOX2WUogZp 4mg30cKjQyXMT49JyY0D366X9X7kEY6kbgTZYNX7d7dygyxvJUbxhlI5XcQvWJH1p/Rc 5TFBrVk3lTGJQVfwHgWGzUh9BI08Gu8bvnwp42pCMI9YOxQKBpeJbA2zju3iDofhf15m rirTvAshDq0U4Zm/NVHZrywd2H2SNUwiP/P23yW0Mqg2iDqtOc1kAZ/8PP1hUcByK3Sr a/8w== X-Forwarded-Encrypted: i=1; AJvYcCWRv4gnSgK6v6WydHTX16ZJQsGavCrWzDp3IP1iQJLczIwcckzgKscNWoGABnXWW8np6RsGTk93ozrxvg==@vger.kernel.org X-Gm-Message-State: AOJu0YzPAkSSjFqxLMjBAc35QY7/GdrPF03CMwThs+m26k4waXUH4TEP YErNeemV/uXOhtFWRCgimj6Ekb3EL4N5BmbNFTHpTk6Jae1uaZSquWLmiD2Li4R5nNxIfzntpBa C7fxyeE+zAhslngROGkgTUYzWXXN94lGvW0cztCN7VFVtURhXyVCR5fExQEg= X-Google-Smtp-Source: AGHT+IHfrW2I3iy1zEHBpfBt4MEcIOr/sBXoPNGPZ2JnNw0WXqO2uRZnlQ8KRmGFbMrhmROW1fej4/pTLXAokJGKAHH8c7+l9/5b Precedence: bulk X-Mailing-List: linux-block@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Received: by 2002:a05:6e02:9e:b0:3dd:b808:be68 with SMTP id e9e14a558f8ab-3e3f62800edmr105194965ab.16.1753928075702; Wed, 30 Jul 2025 19:14:35 -0700 (PDT) Date: Wed, 30 Jul 2025 19:14:35 -0700 X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <688ad18b.a00a0220.26d0e1.0033.GAE@google.com> Subject: [syzbot] [block?] possible deadlock in del_gendisk (2) 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: 302f88ff3584 Merge tag 'for-linus' of git://git.kernel.org.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=152528a2580000 kernel config: https://syzkaller.appspot.com/x/.config?x=27aea6dad68e0c0c dashboard link: https://syzkaller.appspot.com/bug?extid=aea0dfef449ccf91636b compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40 userspace arch: i386 Unfortunately, I don't have any reproducer for this issue yet. Downloadable assets: disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-302f88ff.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/b375ab423051/vmlinux-302f88ff.xz kernel image: https://storage.googleapis.com/syzbot-assets/133b9f21ac36/bzImage-302f88ff.xz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+aea0dfef449ccf91636b@syzkaller.appspotmail.com ====================================================== WARNING: possible circular locking dependency detected 6.16.0-rc7-syzkaller-00127-g302f88ff3584 #0 Not tainted ------------------------------------------------------ syz.7.6877/31320 is trying to acquire lock: but task is already holding lock: ffff8880417fe368 (&set->update_nr_hwq_lock){++++}-{4:4}, at: del_gendisk+0x136/0x1e0 block/genhd.c:822 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (&set->update_nr_hwq_lock){++++}-{4:4}: down_write+0x92/0x200 kernel/locking/rwsem.c:1577 blk_mq_update_nr_hw_queues+0x32/0xcb0 block/blk-mq.c:5041 nbd_start_device+0x172/0xcd0 drivers/block/nbd.c:1476 nbd_start_device_ioctl drivers/block/nbd.c:1527 [inline] __nbd_ioctl drivers/block/nbd.c:1602 [inline] nbd_ioctl+0x219/0xda0 drivers/block/nbd.c:1642 compat_blkdev_ioctl+0x2eb/0x7a0 block/ioctl.c:760 __do_compat_sys_ioctl fs/ioctl.c:1005 [inline] __se_compat_sys_ioctl fs/ioctl.c:948 [inline] __ia32_compat_sys_ioctl+0x23f/0x370 fs/ioctl.c:948 do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:83 [inline] __do_fast_syscall_32+0x7c/0x3a0 arch/x86/entry/syscall_32.c:306 do_fast_syscall_32+0x32/0x80 arch/x86/entry/syscall_32.c:331 entry_SYSENTER_compat_after_hwframe+0x84/0x8e -> #1 (&nbd->config_lock){+.+.}-{4:4}: __mutex_lock_common kernel/locking/mutex.c:602 [inline] __mutex_lock+0x199/0xb90 kernel/locking/mutex.c:747 refcount_dec_and_mutex_lock+0x51/0xc0 lib/refcount.c:118 nbd_config_put+0x31/0x750 drivers/block/nbd.c:1423 nbd_release+0xb7/0x190 drivers/block/nbd.c:1735 blkdev_put_whole+0xb0/0xf0 block/bdev.c:721 bdev_release+0x47e/0x6d0 block/bdev.c:1144 blkdev_release+0x15/0x20 block/fops.c:684 __fput+0x402/0xb70 fs/file_table.c:465 fput_close_sync+0x118/0x260 fs/file_table.c:570 __do_sys_close fs/open.c:1589 [inline] __se_sys_close fs/open.c:1574 [inline] __x64_sys_close+0x8b/0x120 fs/open.c:1574 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xcd/0x490 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #0 (&disk->open_mutex){+.+.}-{4:4}: 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+0x126f/0x1c90 kernel/locking/lockdep.c:5240 lock_acquire kernel/locking/lockdep.c:5871 [inline] lock_acquire+0x179/0x350 kernel/locking/lockdep.c:5828 __mutex_lock_common kernel/locking/mutex.c:602 [inline] __mutex_lock+0x199/0xb90 kernel/locking/mutex.c:747 __del_gendisk+0xf5/0xbd0 block/genhd.c:710 del_gendisk+0x13e/0x1e0 block/genhd.c:823 loop_remove drivers/block/loop.c:2083 [inline] loop_control_remove drivers/block/loop.c:2142 [inline] loop_control_ioctl+0x4f1/0x630 drivers/block/loop.c:2180 __do_compat_sys_ioctl fs/ioctl.c:1005 [inline] __se_compat_sys_ioctl fs/ioctl.c:948 [inline] __ia32_compat_sys_ioctl+0x23f/0x370 fs/ioctl.c:948 do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:83 [inline] __do_fast_syscall_32+0x7c/0x3a0 arch/x86/entry/syscall_32.c:306 do_fast_syscall_32+0x32/0x80 arch/x86/entry/syscall_32.c:331 entry_SYSENTER_compat_after_hwframe+0x84/0x8e other info that might help us debug this: Chain exists of: &disk->open_mutex --> &nbd->config_lock --> &set->update_nr_hwq_lock Possible unsafe locking scenario: CPU0 CPU1 ---- ---- rlock(&set->update_nr_hwq_lock); lock(&nbd->config_lock); lock(&set->update_nr_hwq_lock); lock(&disk->open_mutex); *** DEADLOCK *** 1 lock held by syz.7.6877/31320: #0: ffff8880417fe368 (&set->update_nr_hwq_lock){++++}-{4:4}, at: del_gendisk+0x136/0x1e0 block/genhd.c:822 stack backtrace: CPU: 0 UID: 0 PID: 31320 Comm: syz.7.6877 Not tainted 6.16.0-rc7-syzkaller-00127-g302f88ff3584 #0 PREEMPT(full) Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014 Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120 print_circular_bug+0x275/0x350 kernel/locking/lockdep.c:2046 check_noncircular+0x14c/0x170 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+0x126f/0x1c90 kernel/locking/lockdep.c:5240 lock_acquire kernel/locking/lockdep.c:5871 [inline] lock_acquire+0x179/0x350 kernel/locking/lockdep.c:5828 __mutex_lock_common kernel/locking/mutex.c:602 [inline] __mutex_lock+0x199/0xb90 kernel/locking/mutex.c:747 __del_gendisk+0xf5/0xbd0 block/genhd.c:710 del_gendisk+0x13e/0x1e0 block/genhd.c:823 loop_remove drivers/block/loop.c:2083 [inline] loop_control_remove drivers/block/loop.c:2142 [inline] loop_control_ioctl+0x4f1/0x630 drivers/block/loop.c:2180 __do_compat_sys_ioctl fs/ioctl.c:1005 [inline] __se_compat_sys_ioctl fs/ioctl.c:948 [inline] __ia32_compat_sys_ioctl+0x23f/0x370 fs/ioctl.c:948 do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:83 [inline] __do_fast_syscall_32+0x7c/0x3a0 arch/x86/entry/syscall_32.c:306 do_fast_syscall_32+0x32/0x80 arch/x86/entry/syscall_32.c:331 entry_SYSENTER_compat_after_hwframe+0x84/0x8e RIP: 0023:0xf70be579 Code: b8 01 10 06 03 74 b4 01 10 07 03 74 b0 01 10 08 03 74 d8 01 00 00 00 00 00 00 00 00 00 00 00 00 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 8d b4 26 00 00 00 00 8d b4 26 00 00 00 00 RAX: ffffffffffffffda RBX: 0000000000000008 RCX: 0000000000004c81 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000296 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 ---------------- Code disassembly (best guess), 2 bytes skipped: 0: 10 06 adc %al,(%rsi) 2: 03 74 b4 01 add 0x1(%rsp,%rsi,4),%esi 6: 10 07 adc %al,(%rdi) 8: 03 74 b0 01 add 0x1(%rax,%rsi,4),%esi c: 10 08 adc %cl,(%rax) e: 03 74 d8 01 add 0x1(%rax,%rbx,8),%esi 1e: 00 51 52 add %dl,0x52(%rcx) 21: 55 push %rbp 22: 89 e5 mov %esp,%ebp 24: 0f 34 sysenter 26: cd 80 int $0x80 * 28: 5d pop %rbp <-- trapping instruction 29: 5a pop %rdx 2a: 59 pop %rcx 2b: c3 ret 2c: 90 nop 2d: 90 nop 2e: 90 nop 2f: 90 nop 30: 8d b4 26 00 00 00 00 lea 0x0(%rsi,%riz,1),%esi 37: 8d b4 26 00 00 00 00 lea 0x0(%rsi,%riz,1),%esi --- 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