From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-oa1-f79.google.com (mail-oa1-f79.google.com [209.85.160.79]) (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 72ED7282F1F for ; Tue, 11 Aug 2026 00:24:39 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.160.79 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786407881; cv=none; b=Dq//eulCL3D9L7PT4KBWG2Da72w46/k5OkGlkpqoiVacn24fqEnL63tWaBlvGFU13YbkNAfudy0pJ+ZZXYXsIWvnCNv+JiZk4jgYlQ+qaVjnbzx0rb4QXGaWrTr6NF4EVm61z/cTfm+lTwiyFMtUgTR3LT6Iug4t8KIN4eEbRo0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786407881; c=relaxed/simple; bh=eFaL3PhCM5GHJIoFVqTIXGCmnCfmQTeTPnHVkMcgzFo=; h=MIME-Version:Date:Message-ID:Subject:From:To:Content-Type; b=s8Um6ZeHnN369TOwF6Tml/9lDhDj0zQJUlOiEuJeMka0GwHh2YCSlbGZEAWdSFshywEB+3YyRaiJhDKgvIsIipWeOT9fw+lb7LJUh58e3NKYqwaSR38q/k0+I8CGVxrRDsKAhHRWsQ3cFHJdnb/rfxW/h34130NlapYuXJFBS9Y= 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=209.85.160.79 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-oa1-f79.google.com with SMTP id 586e51a60fabf-44d0960fb5bso2382973fac.2 for ; Mon, 10 Aug 2026 17:24:39 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1786407878; x=1787012678; h=content-type:to:from:subject:message-id:date:mime-version :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to :content-type; bh=XQnErzs2gusx3xUaACthm5DWDtRQ37KBnVLE5kRuOhw=; b=DbU6rfVNDDYCLAZnMJb7WeiFYouXKiOhY45yIRkcUhLGqRG0PyTfGl3E3HrPrlIOOl guFymMbfmIRxYA0BIm2hofdwABvWuXV/isXfmj0lrWazc+GD/kNzcsVca2g8HeiQww3A YKC2s87Q6IrBybLuEy9ONAVM4Btysr7DqBJN2NWN4Qa6O01FyP4TXkITEy4+LcTgkj6C 2/BNQYX+CyQDPnE5R/B/nQ+cWPU7O8GFYq+SqyBQY84vMMJWNXYeEGA4a69kDXkPNfPf ENpqglJJBM4NMhX6PsbdIxyFd3nV/s8+eJMG2XXP7vvfeD5nOPm99/z7aM1Gp59ioM4J Di0g== X-Forwarded-Encrypted: i=1; AHgh+RpTpCQf2JFYy6NGO5GZuI3qj9vqk5dNC8iL00lZQmfkHJUHPgPIrG/+Nua/tZxfBzPhTUw98JnXkw1LmFU=@vger.kernel.org X-Gm-Message-State: AOJu0YzwBaGPRMrkE6P6fxpZ3s798GCOOCvSEVdBIRI9aCDAxQrTiVcq mPqfyLGU9KgWxQhix1fNDM7oTZFow7g83ZhbgV9OQLr4pQSe6Q+by6qTEznOD85WMUiA2iqq/L0 8cvkSBKp5tdLd3CEZUMLoiL8EVt6iX3tzyslZD6uvj03qhRpO9JiajRwxL30= Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Received: by 2002:a05:6808:c198:b0:491:3ade:8ba0 with SMTP id 5614622812f47-4b1e7936f09mr3127397b6e.16.1786407878534; Mon, 10 Aug 2026 17:24:38 -0700 (PDT) Date: Mon, 10 Aug 2026 17:24:38 -0700 X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <6a7a6bc6.01d0871a.3a0d52.00b3.GAE@google.com> Subject: [syzbot] [fs?] possible deadlock in configfs_detach_group From: syzbot To: a.hindborg@kernel.org, leitao@debian.org, linux-fsdevel@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: c21bb4193868 Merge tag 'for_linus' of git://git.kernel.org.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=14a63bb9580000 kernel config: https://syzkaller.appspot.com/x/.config?x=f221a1b5d497ed15 dashboard link: https://syzkaller.appspot.com/bug?extid=245b08b227dcdeb63e2c compiler: gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44 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-c21bb419.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/ff1def389cf6/vmlinux-c21bb419.xz kernel image: https://storage.googleapis.com/syzbot-assets/ab751d30f9d2/bzImage-c21bb419.xz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+245b08b227dcdeb63e2c@syzkaller.appspotmail.com ====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Not tainted ------------------------------------------------------ syz.3.304/7178 is trying to acquire lock: ffff8880005e4880 (&default_group_class[depth - 1]#9){+.+.}-{4:4}, at: inode_lock include/linux/fs.h:1024 [inline] ffff8880005e4880 (&default_group_class[depth - 1]#9){+.+.}-{4:4}, at: detach_groups fs/configfs/dir.c:680 [inline] ffff8880005e4880 (&default_group_class[depth - 1]#9){+.+.}-{4:4}, at: configfs_detach_group+0x21c/0x440 fs/configfs/dir.c:887 but task is already holding lock: ffff8880005e1900 (&default_group_class[depth - 1]#8){++++}-{4:4}, at: inode_lock include/linux/fs.h:1024 [inline] ffff8880005e1900 (&default_group_class[depth - 1]#8){++++}-{4:4}, at: detach_groups fs/configfs/dir.c:680 [inline] ffff8880005e1900 (&default_group_class[depth - 1]#8){++++}-{4:4}, at: configfs_detach_group+0x21c/0x440 fs/configfs/dir.c:887 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #5 (&default_group_class[depth - 1]#8){++++}-{4:4}: lock_acquire kernel/locking/lockdep.c:5868 [inline] lock_acquire+0x1b9/0x370 kernel/locking/lockdep.c:5825 down_write+0x8b/0x1f0 kernel/locking/rwsem.c:1631 inode_lock include/linux/fs.h:1024 [inline] detach_groups fs/configfs/dir.c:680 [inline] configfs_detach_group+0x21c/0x440 fs/configfs/dir.c:887 detach_groups fs/configfs/dir.c:682 [inline] configfs_detach_group+0x224/0x440 fs/configfs/dir.c:887 configfs_rmdir+0x598/0x950 fs/configfs/dir.c:1554 vfs_rmdir fs/namei.c:5381 [inline] vfs_rmdir+0x328/0x8a0 fs/namei.c:5354 filename_rmdir+0x31a/0x5c0 fs/namei.c:5438 __do_sys_rmdir fs/namei.c:5461 [inline] __se_sys_rmdir fs/namei.c:5458 [inline] __ia32_sys_rmdir+0x45/0x60 fs/namei.c:5458 do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:83 [inline] __do_fast_syscall_32+0xe7/0x970 arch/x86/entry/syscall_32.c:307 do_fast_syscall_32+0x32/0x70 arch/x86/entry/syscall_32.c:332 entry_SYSENTER_compat_after_hwframe+0x84/0x8e -> #4 (&default_group_class[depth - 1]#2){+.+.}-{4:4}: lock_acquire kernel/locking/lockdep.c:5868 [inline] lock_acquire+0x1b9/0x370 kernel/locking/lockdep.c:5825 down_write+0x8b/0x1f0 kernel/locking/rwsem.c:1631 inode_lock include/linux/fs.h:1024 [inline] detach_groups fs/configfs/dir.c:680 [inline] configfs_detach_group+0x21c/0x440 fs/configfs/dir.c:887 configfs_rmdir+0x598/0x950 fs/configfs/dir.c:1554 vfs_rmdir fs/namei.c:5381 [inline] vfs_rmdir+0x328/0x8a0 fs/namei.c:5354 filename_rmdir+0x31a/0x5c0 fs/namei.c:5438 __do_sys_rmdir fs/namei.c:5461 [inline] __se_sys_rmdir fs/namei.c:5458 [inline] __ia32_sys_rmdir+0x45/0x60 fs/namei.c:5458 do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:83 [inline] __do_fast_syscall_32+0xe7/0x970 arch/x86/entry/syscall_32.c:307 do_fast_syscall_32+0x32/0x70 arch/x86/entry/syscall_32.c:332 entry_SYSENTER_compat_after_hwframe+0x84/0x8e -> #3 (&sb->s_type->i_mutex_key#26){++++}-{4:4}: lock_acquire kernel/locking/lockdep.c:5868 [inline] lock_acquire+0x1b9/0x370 kernel/locking/lockdep.c:5825 down_write+0x8b/0x1f0 kernel/locking/rwsem.c:1631 inode_lock include/linux/fs.h:1024 [inline] configfs_depend_item_unlocked+0xf3/0x6a0 fs/configfs/dir.c:1259 usbg_make_tpg+0x261/0x620 drivers/usb/gadget/function/f_tcm.c:1686 target_fabric_make_tpg+0xab/0x8c0 drivers/target/target_core_fabric_configfs.c:939 configfs_mkdir+0x51e/0xb70 fs/configfs/dir.c:1360 vfs_mkdir+0x361/0x850 fs/namei.c:5276 filename_mkdirat+0x48b/0x5e0 fs/namei.c:5309 __do_sys_mkdir fs/namei.c:5336 [inline] __se_sys_mkdir fs/namei.c:5333 [inline] __ia32_sys_mkdir+0x6a/0x90 fs/namei.c:5333 do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:83 [inline] __do_fast_syscall_32+0xe7/0x970 arch/x86/entry/syscall_32.c:307 do_fast_syscall_32+0x32/0x70 arch/x86/entry/syscall_32.c:332 entry_SYSENTER_compat_after_hwframe+0x84/0x8e -> #2 (&opts->dep_lock){+.+.}-{4:4}: lock_acquire kernel/locking/lockdep.c:5868 [inline] lock_acquire+0x1b9/0x370 kernel/locking/lockdep.c:5825 __mutex_lock_common kernel/locking/mutex.c:646 [inline] __mutex_lock+0x1a4/0x1bd0 kernel/locking/mutex.c:821 tcm_set_name+0x29/0xb0 drivers/usb/gadget/function/f_tcm.c:2669 function_make+0x21c/0x3f0 drivers/usb/gadget/configfs.c:636 configfs_mkdir+0x51e/0xb70 fs/configfs/dir.c:1360 vfs_mkdir+0x361/0x850 fs/namei.c:5276 filename_mkdirat+0x48b/0x5e0 fs/namei.c:5309 __do_sys_mkdir fs/namei.c:5336 [inline] __se_sys_mkdir fs/namei.c:5333 [inline] __ia32_sys_mkdir+0x6a/0x90 fs/namei.c:5333 do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:83 [inline] __do_fast_syscall_32+0xe7/0x970 arch/x86/entry/syscall_32.c:307 do_fast_syscall_32+0x32/0x70 arch/x86/entry/syscall_32.c:332 entry_SYSENTER_compat_after_hwframe+0x84/0x8e -> #1 (gadget_subsys.su_mutex){+.+.}-{4:4}: lock_acquire kernel/locking/lockdep.c:5868 [inline] lock_acquire+0x1b9/0x370 kernel/locking/lockdep.c:5825 __mutex_lock_common kernel/locking/mutex.c:646 [inline] __mutex_lock+0x1a4/0x1bd0 kernel/locking/mutex.c:821 uvcg_streaming_class_allow_link+0x100/0x6b0 drivers/usb/gadget/function/uvc_configfs.c:3432 configfs_symlink+0x540/0x11f0 fs/configfs/symlink.c:196 vfs_symlink fs/namei.c:5660 [inline] vfs_symlink+0x178/0x4d0 fs/namei.c:5639 filename_symlinkat+0x2a6/0x560 fs/namei.c:5685 __do_sys_symlinkat fs/namei.c:5705 [inline] __se_sys_symlinkat fs/namei.c:5700 [inline] __ia32_sys_symlinkat+0x9b/0xe0 fs/namei.c:5700 do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:83 [inline] __do_fast_syscall_32+0xe7/0x970 arch/x86/entry/syscall_32.c:307 do_fast_syscall_32+0x32/0x70 arch/x86/entry/syscall_32.c:332 entry_SYSENTER_compat_after_hwframe+0x84/0x8e -> #0 (&default_group_class[depth - 1]#9){+.+.}-{4:4}: check_prev_add+0xeb/0xe60 kernel/locking/lockdep.c:3165 check_prevs_add kernel/locking/lockdep.c:3284 [inline] validate_chain kernel/locking/lockdep.c:3908 [inline] __lock_acquire+0x136c/0x1a40 kernel/locking/lockdep.c:5237 lock_acquire kernel/locking/lockdep.c:5868 [inline] lock_acquire+0x1b9/0x370 kernel/locking/lockdep.c:5825 down_write+0x8b/0x1f0 kernel/locking/rwsem.c:1631 inode_lock include/linux/fs.h:1024 [inline] detach_groups fs/configfs/dir.c:680 [inline] configfs_detach_group+0x21c/0x440 fs/configfs/dir.c:887 detach_groups fs/configfs/dir.c:682 [inline] configfs_detach_group+0x224/0x440 fs/configfs/dir.c:887 detach_groups fs/configfs/dir.c:682 [inline] configfs_detach_group+0x224/0x440 fs/configfs/dir.c:887 configfs_rmdir+0x598/0x950 fs/configfs/dir.c:1554 vfs_rmdir fs/namei.c:5381 [inline] vfs_rmdir+0x328/0x8a0 fs/namei.c:5354 filename_rmdir+0x31a/0x5c0 fs/namei.c:5438 __do_sys_rmdir fs/namei.c:5461 [inline] __se_sys_rmdir fs/namei.c:5458 [inline] __ia32_sys_rmdir+0x45/0x60 fs/namei.c:5458 do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:83 [inline] __do_fast_syscall_32+0xe7/0x970 arch/x86/entry/syscall_32.c:307 do_fast_syscall_32+0x32/0x70 arch/x86/entry/syscall_32.c:332 entry_SYSENTER_compat_after_hwframe+0x84/0x8e other info that might help us debug this: Chain exists of: &default_group_class[depth - 1]#9 --> &default_group_class[depth - 1]#2 --> &default_group_class[depth - 1]#8 Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&default_group_class[depth - 1]#8); lock(&default_group_class[depth - 1]#2); lock(&default_group_class[depth - 1]#8); lock(&default_group_class[depth - 1]#9); *** DEADLOCK *** 5 locks held by syz.3.304/7178: #0: ffff88802250c450 (sb_writers#15){.+.+}-{0:0}, at: filename_rmdir+0x1ff/0x5c0 fs/namei.c:5427 #1: ffff888013f76e80 (&default_group_class[depth - 1]#2/1){+.+.}-{4:4}, at: inode_lock_nested include/linux/fs.h:1069 [inline] #1: ffff888013f76e80 (&default_group_class[depth - 1]#2/1){+.+.}-{4:4}, at: __start_dirop fs/namei.c:2918 [inline] #1: ffff888013f76e80 (&default_group_class[depth - 1]#2/1){+.+.}-{4:4}, at: start_dirop fs/namei.c:2942 [inline] #1: ffff888013f76e80 (&default_group_class[depth - 1]#2/1){+.+.}-{4:4}, at: filename_rmdir+0x258/0x5c0 fs/namei.c:5431 #2: ffff8880005e0f80 (&sb->s_type->i_mutex_key#26){++++}-{4:4}, at: inode_lock include/linux/fs.h:1024 [inline] #2: ffff8880005e0f80 (&sb->s_type->i_mutex_key#26){++++}-{4:4}, at: vfs_rmdir fs/namei.c:5366 [inline] #2: ffff8880005e0f80 (&sb->s_type->i_mutex_key#26){++++}-{4:4}, at: vfs_rmdir+0xed/0x8a0 fs/namei.c:5354 #3: ffff8880005e6e80 (&default_group_class[depth - 1]#2){+.+.}-{4:4}, at: inode_lock include/linux/fs.h:1024 [inline] #3: ffff8880005e6e80 (&default_group_class[depth - 1]#2){+.+.}-{4:4}, at: detach_groups fs/configfs/dir.c:680 [inline] #3: ffff8880005e6e80 (&default_group_class[depth - 1]#2){+.+.}-{4:4}, at: configfs_detach_group+0x21c/0x440 fs/configfs/dir.c:887 #4: ffff8880005e1900 (&default_group_class[depth - 1]#8){++++}-{4:4}, at: inode_lock include/linux/fs.h:1024 [inline] #4: ffff8880005e1900 (&default_group_class[depth - 1]#8){++++}-{4:4}, at: detach_groups fs/configfs/dir.c:680 [inline] #4: ffff8880005e1900 (&default_group_class[depth - 1]#8){++++}-{4:4}, at: configfs_detach_group+0x21c/0x440 fs/configfs/dir.c:887 stack backtrace: CPU: 3 UID: 0 PID: 7178 Comm: syz.3.304 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+0x178/0x1c7 kernel/locking/lockdep.c:2043 check_noncircular+0x146/0x160 kernel/locking/lockdep.c:2175 check_prev_add+0xeb/0xe60 kernel/locking/lockdep.c:3165 check_prevs_add kernel/locking/lockdep.c:3284 [inline] validate_chain kernel/locking/lockdep.c:3908 [inline] __lock_acquire+0x136c/0x1a40 kernel/locking/lockdep.c:5237 lock_acquire kernel/locking/lockdep.c:5868 [inline] lock_acquire+0x1b9/0x370 kernel/locking/lockdep.c:5825 down_write+0x8b/0x1f0 kernel/locking/rwsem.c:1631 inode_lock include/linux/fs.h:1024 [inline] detach_groups fs/configfs/dir.c:680 [inline] configfs_detach_group+0x21c/0x440 fs/configfs/dir.c:887 detach_groups fs/configfs/dir.c:682 [inline] configfs_detach_group+0x224/0x440 fs/configfs/dir.c:887 detach_groups fs/configfs/dir.c:682 [inline] configfs_detach_group+0x224/0x440 fs/configfs/dir.c:887 configfs_rmdir+0x598/0x950 fs/configfs/dir.c:1554 vfs_rmdir fs/namei.c:5381 [inline] vfs_rmdir+0x328/0x8a0 fs/namei.c:5354 filename_rmdir+0x31a/0x5c0 fs/namei.c:5438 __do_sys_rmdir fs/namei.c:5461 [inline] __se_sys_rmdir fs/namei.c:5458 [inline] __ia32_sys_rmdir+0x45/0x60 fs/namei.c:5458 do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:83 [inline] __do_fast_syscall_32+0xe7/0x970 arch/x86/entry/syscall_32.c:307 do_fast_syscall_32+0x32/0x70 arch/x86/entry/syscall_32.c:332 entry_SYSENTER_compat_after_hwframe+0x84/0x8e RIP: 0023:0xf7ff3fec Code: Unable to access opcode bytes at 0xf7ff3fc2. RSP: 002b:00000000f54b650c EFLAGS: 00000292 ORIG_RAX: 0000000000000028 RAX: ffffffffffffffda RBX: 0000000080000200 RCX: 0000000000000000 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000292 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 --- 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. 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