From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-oa2-f9.google.com (mail-oa2-f9.google.com [74.125.231.73]) (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 D8B74274650 for ; Wed, 16 Sep 2026 02:15:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=74.125.231.73 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789524947; cv=none; b=iZU5HdXW3q2q7EVj5UCCKPs+XLRwUvFSz6NHqseqB6g5Kq19HnbQwRyA1MKw00RB1CcI6nxWU2ydhHuCGBUxu8INjfTSztRd9gNbOWrbYzLSg8a11+N0eoPcaQmBUUF4mRF+tQSSVDdKfZNnM2H5MX5sluIjypF3IaCbaVWiQHI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789524947; c=relaxed/simple; bh=2H60UeEyFUGtJ2Hs4Q/9QGKw7hhhE6EVirUtBXZOGQk=; h=MIME-Version:Date:Message-ID:Subject:From:To:Content-Type; b=ZEYMCxNQhw4TIRf1YxmOMqL6sUIBY8T5WwSvvTO3ZhGH4EO0s/P+1+xH00gD1DBFnwj3X4o7nB74xoEKMpaU/OdHqtbtjLVRvb8DDiYJ/508yw2kSfjJADTcx6bMudgfcsI0zZ5LaAa2miV6JZiJnMoFjTYKEITj7v1wvlKDis8= 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=74.125.231.73 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-oa2-f9.google.com with SMTP id 586e51a60fabf-47cf5b09bf1so1874957fac.1 for ; Tue, 15 Sep 2026 19:15:38 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20260707; t=1789524934; x=1790129734; 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=KW8L0IZy9f8Ym6HcpkcmLukANbz/LCl2l9Bg0IabelI=; b=d2SZ9DsB50Tz8/y+MIxQC+PBdDX5pXabN4OjMvBiHsU1LdUroejWZKWMu567+jnK+B WbZA139zBAAcMK+7Q/OA2vxOhpH5FA/i13EUzn8v2Aqj+vKJqodUv5YehS17fwYSQx8U lTOqnDxgUeh85pPjNrZLed3+niB/uZDIadGhJBx/TKxInKGErnfhPQpw0oz0JbKKLywh rICB4KQaPG/9LZlmTdODPDPoWmHePJyymYD8dMRNaLHTTCIWYmar72mAduGa5K9v1IrG 4bBZ7UumyQBcrAkzlPmiQV9XXcULmU5YHBm4n4x/3V8bD5Zcj6ccny1WHis2wYrTSMUX QjBw== X-Forwarded-Encrypted: i=1; AKwUvBykDm+m9az0cVtwJy2cvs2OdMEYHgRQ7ZKbAF0y6FL0BEVOPaJt3gRK7ZJimydUV0gjfriNy/d6r3LLJm8=@vger.kernel.org X-Gm-Message-State: AFuF++mqaGsnEt9pOQmbslDrbUfyDmF4g2fmxY3j+AiitHwQsrIgEkWV lY6PmPHeEtuLU6DH1USPukXWucBPo23mLDi2sBNNTTAnxf9QexYvJE8GjY+PMzM7pM1fNmGMosc gddnere5965FFSLYm7YHVi0Y686SDhA9DZnKOBqzAq8w6wUqT1lJcUmBz0Zs= Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Received: by 2002:a05:6808:170c:b0:4c5:12a4:ec8a with SMTP id 5614622812f47-4ca4c2828e9mr1113235b6e.36.1789524934451; Tue, 15 Sep 2026 19:15:34 -0700 (PDT) Date: Tue, 15 Sep 2026 19:15:34 -0700 X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <6aa9fbc6.4c28b7d0.c1bba.0043.GAE@google.com> Subject: [syzbot] [fs?] possible deadlock in uvcg_format_bma_controls_store 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: 3026c6e4f223 Merge tag 'slab-for-7.3-rc2' of git://git.ker.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=11f1e901580000 kernel config: https://syzkaller.appspot.com/x/.config?x=5e4e3a0e188a497e dashboard link: https://syzkaller.appspot.com/bug?extid=50560f9ba016e97e2023 compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8 Unfortunately, I don't have any reproducer for this issue yet. Downloadable assets: disk image: https://storage.googleapis.com/syzbot-assets/98fa15ee8f48/disk-3026c6e4.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/36b1db5cf167/vmlinux-3026c6e4.xz kernel image: https://storage.googleapis.com/syzbot-assets/3f745756a36c/bzImage-3026c6e4.xz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+50560f9ba016e97e2023@syzkaller.appspotmail.com ====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Tainted: G L ------------------------------------------------------ syz.3.8436/729 is trying to acquire lock: ffffffff8fc11b68 (gadget_subsys.su_mutex){+.+.}-{4:4}, at: uvcg_format_bma_controls_store+0x55/0x2b0 drivers/usb/gadget/function/uvc_configfs.c:1707 but task is already holding lock: ffff888028d20770 (&p->frag_sem){++++}-{4:4}, at: flush_write_buffer fs/configfs/file.c:205 [inline] ffff888028d20770 (&p->frag_sem){++++}-{4:4}, at: configfs_write_iter+0x238/0x430 fs/configfs/file.c:229 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #4 (&p->frag_sem){++++}-{4:4}: down_write_killable+0xa6/0x240 kernel/locking/rwsem.c:1643 configfs_rmdir+0x3b0/0x950 fs/configfs/dir.c:1543 vfs_rmdir+0x3e6/0x6a0 fs/namei.c:5515 filename_rmdir+0x292/0x520 fs/namei.c:5572 __do_sys_unlinkat fs/namei.c:5747 [inline] __se_sys_unlinkat+0x71/0x1a0 fs/namei.c:5740 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline] do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #3 (&sb->s_type->i_mutex_key#27){++++}-{4:4}: down_write+0x96/0x200 kernel/locking/rwsem.c:1631 inode_lock include/linux/fs.h:1024 [inline] configfs_depend_item_unlocked+0x153/0x420 fs/configfs/dir.c:1268 usbg_make_tpg+0x1e0/0x550 drivers/usb/gadget/function/f_tcm.c:1692 target_fabric_make_tpg+0xa8/0x6d0 drivers/target/target_core_fabric_configfs.c:947 configfs_mkdir+0x4f6/0x9e0 fs/configfs/dir.c:1369 vfs_mkdir+0x40c/0x620 fs/namei.c:5410 filename_mkdirat+0x285/0x510 fs/namei.c:5443 __do_sys_mkdir fs/namei.c:5470 [inline] __se_sys_mkdir+0x34/0x150 fs/namei.c:5467 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline] do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #2 (tpg_instances_lock){+.+.}-{4:4}: __mutex_lock_common kernel/locking/mutex.c:646 [inline] __mutex_lock+0x19d/0x1550 kernel/locking/mutex.c:821 tcm_alloc_inst+0x65/0x1a0 drivers/usb/gadget/function/f_tcm.c:2687 try_get_usb_function_instance drivers/usb/gadget/functions.c:28 [inline] usb_get_function_instance+0xe3/0x2f0 drivers/usb/gadget/functions.c:44 function_make+0x127/0x360 drivers/usb/gadget/configfs.c:626 configfs_mkdir+0x4f6/0x9e0 fs/configfs/dir.c:1369 vfs_mkdir+0x40c/0x620 fs/namei.c:5410 filename_mkdirat+0x285/0x510 fs/namei.c:5443 __do_sys_mkdir fs/namei.c:5470 [inline] __se_sys_mkdir+0x34/0x150 fs/namei.c:5467 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline] do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #1 (func_lock){+.+.}-{4:4}: __mutex_lock_common kernel/locking/mutex.c:646 [inline] __mutex_lock+0x19d/0x1550 kernel/locking/mutex.c:821 try_get_usb_function_instance drivers/usb/gadget/functions.c:18 [inline] usb_get_function_instance+0x2e/0x2f0 drivers/usb/gadget/functions.c:44 function_make+0x127/0x360 drivers/usb/gadget/configfs.c:626 configfs_mkdir+0x4f6/0x9e0 fs/configfs/dir.c:1369 vfs_mkdir+0x40c/0x620 fs/namei.c:5410 filename_mkdirat+0x285/0x510 fs/namei.c:5443 __do_sys_mkdir fs/namei.c:5470 [inline] __se_sys_mkdir+0x34/0x150 fs/namei.c:5467 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline] do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #0 (gadget_subsys.su_mutex){+.+.}-{4:4}: check_prev_add kernel/locking/lockdep.c:3209 [inline] check_prevs_add kernel/locking/lockdep.c:3328 [inline] validate_chain kernel/locking/lockdep.c:3952 [inline] __lock_acquire+0x164c/0x2de0 kernel/locking/lockdep.c:5288 lock_acquire+0x115/0x350 kernel/locking/lockdep.c:5942 __mutex_lock_common kernel/locking/mutex.c:646 [inline] __mutex_lock+0x19d/0x1550 kernel/locking/mutex.c:821 uvcg_format_bma_controls_store+0x55/0x2b0 drivers/usb/gadget/function/uvc_configfs.c:1707 flush_write_buffer fs/configfs/file.c:207 [inline] configfs_write_iter+0x337/0x430 fs/configfs/file.c:229 new_sync_write fs/read_write.c:595 [inline] vfs_write+0x612/0xba0 fs/read_write.c:687 ksys_write+0x150/0x270 fs/read_write.c:739 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline] do_syscall_64+0x166/0x520 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: gadget_subsys.su_mutex --> &sb->s_type->i_mutex_key#27 --> &p->frag_sem Possible unsafe locking scenario: CPU0 CPU1 ---- ---- rlock(&p->frag_sem); lock(&sb->s_type->i_mutex_key#27); lock(&p->frag_sem); lock(gadget_subsys.su_mutex); *** DEADLOCK *** locks held by syz.3.8436/729: 4, last CPU#1: #0: ffff88802cacd270 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x246/0x320 fs/file.c:1259 #1: ffff88801d716460 (sb_writers#16){.+.+}-{0:0}, at: file_start_write include/linux/fs.h:2753 [inline] #1: ffff88801d716460 (sb_writers#16){.+.+}-{0:0}, at: vfs_write+0x22b/0xba0 fs/read_write.c:683 #2: ffff888076ff2c80 (&buffer->mutex#2){+.+.}-{4:4}, at: configfs_write_iter+0x7e/0x430 fs/configfs/file.c:226 #3: ffff888028d20770 (&p->frag_sem){++++}-{4:4}, at: flush_write_buffer fs/configfs/file.c:205 [inline] #3: ffff888028d20770 (&p->frag_sem){++++}-{4:4}, at: configfs_write_iter+0x238/0x430 fs/configfs/file.c:229 stack backtrace: CPU: 1 UID: 0 PID: 729 Comm: syz.3.8436 Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/05/2026 Call Trace: dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120 print_circular_bug+0x2e2/0x300 kernel/locking/lockdep.c:2087 check_noncircular+0x12f/0x150 kernel/locking/lockdep.c:2219 check_prev_add kernel/locking/lockdep.c:3209 [inline] check_prevs_add kernel/locking/lockdep.c:3328 [inline] validate_chain kernel/locking/lockdep.c:3952 [inline] __lock_acquire+0x164c/0x2de0 kernel/locking/lockdep.c:5288 lock_acquire+0x115/0x350 kernel/locking/lockdep.c:5942 __mutex_lock_common kernel/locking/mutex.c:646 [inline] __mutex_lock+0x19d/0x1550 kernel/locking/mutex.c:821 uvcg_format_bma_controls_store+0x55/0x2b0 drivers/usb/gadget/function/uvc_configfs.c:1707 flush_write_buffer fs/configfs/file.c:207 [inline] configfs_write_iter+0x337/0x430 fs/configfs/file.c:229 new_sync_write fs/read_write.c:595 [inline] vfs_write+0x612/0xba0 fs/read_write.c:687 ksys_write+0x150/0x270 fs/read_write.c:739 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline] do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fee74b9e159 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:00007fee7597e028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 00007fee74e25fa0 RCX: 00007fee74b9e159 RDX: 0000000000000002 RSI: 0000200000000300 RDI: 0000000000000003 RBP: 00007fee74c3503b R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fee74e26038 R14: 00007fee74e25fa0 R15: 00007ffd3a9e87e8 --- This report is generated by a bot. 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