From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-oo1-f80.google.com (mail-oo1-f80.google.com [209.85.161.80]) (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 A1C532BEC55 for ; Wed, 19 Aug 2026 13:59:25 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.161.80 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787147967; cv=none; b=ijhz4/C6S6o4wCWuqgjmjsL3ca7Xr8Y2oqWORwVdelKDE0uZ0MTBFHnnbczM/phtXydLA2fg31QQnbs2g0FLL5+V/mjxg0nO8YTtN1tXTmzsO8OayuE/4QXu5nmmt0DCOobqr7SO+J6tAPlMPaq5qZJnFpS0FPVbPMufcWZ7qLA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787147967; c=relaxed/simple; bh=lkwd4xaWDH9v1h5LPrq9bIkv9SP3Cdwxy90Cw4GuRNg=; h=MIME-Version:Date:Message-ID:Subject:From:To:Content-Type; b=jgAG0SuzsGFQfIVWiR4/79pXxRQUDcMWGtS3C2sE46+rL5FlUgK6J8ty1lh7fYbDCOKnpFucEfE97cl0ajuhZFwyUB6UoyR4ELC6hA1Q8Bgt1/A66sEThPY/njha06OPjpRJb813j5uqgtYWMM76Fw1jZA4VLiQqbuXNo3Hzi4c= 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=209.85.161.80 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-f80.google.com with SMTP id 006d021491bc7-6b137fac47aso813629eaf.2 for ; Wed, 19 Aug 2026 06:59:25 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1787147964; x=1787752764; 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=unTYUURzWODVnb8yGUpkuzSl+ZwsipDCuvxKtdFso8o=; b=b3UpFP2FUEiGHIQxevI5KNoNacWNPvAl6j2hH3dfwgfjlZOtbgqTq6iwwKVxeWtLvU OAMJsAmg+W4KxVmxMsilgffgo4wLjCRrh3BMtoddjXQ60M/urI1YENTlmsjhp3CTF5kI PdV/WKcOy3Qb+9WG5BADQGo6fW84AX1+pG+bLW0VPjV5Pt7gzWDTUSFfN9cjF5mZBKzw kp11VO3qfMcidLRoqVIEVWst29IJBDDhlhOfhffXY6kVWcAtRfE4MHLjrfH9n4Eovadr atW+bG1L9GDXqI8rkAPrIE+icirClrhzuYjEX43IzG3lyLXwnhklhGfRGItFqc07Pn2j LrUQ== X-Forwarded-Encrypted: i=1; AHgh+RrQbm8h9mMwTeCG+4zOhdK8JcFdgQu/ZKyWIUvsRpo6NVodqw9+Khd02beGHXN791bQYmcX592QPd3AJxk=@vger.kernel.org X-Gm-Message-State: AOJu0YwCZCsoKP+GO8k/CXnvDDMI/ZLmfECii6WdauU9sHOosjPkQ/mX Y/6dqnA0nApV7IIOBC4Kg0cp+2Oxv/4rJi82mv+nyFzRTRT7lCpPbeNCHV5GjcWfaioAQ2i4B6t gq11L8NgQuFIdCMa8PDTmPEr6B0nH1rgaMJPvcD6lKne1NSyLr6U97yzfkwg= Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Received: by 2002:a05:6820:811b:b0:6b0:dfa2:8315 with SMTP id 006d021491bc7-6b13c348134mr4519816eaf.13.1787147964561; Wed, 19 Aug 2026 06:59:24 -0700 (PDT) Date: Wed, 19 Aug 2026 06:59:24 -0700 X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <6a85b6bc.c8649fcc.3bb87.0011.GAE@google.com> Subject: [syzbot] [fs?] possible deadlock in uvcg_frame_dw_max_video_frame_buffer_size_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: 15ef2f78c49d Merge tag 'input-for-v7.2-rc7' of git://git.k.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=1167ca25580000 kernel config: https://syzkaller.appspot.com/x/.config?x=2ca5f2f2c4197664 dashboard link: https://syzkaller.appspot.com/bug?extid=52720fcb44cb7f79c0cd 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/d913f78d9891/disk-15ef2f78.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/d5273ff4be42/vmlinux-15ef2f78.xz kernel image: https://storage.googleapis.com/syzbot-assets/71fd7f7b71b6/bzImage-15ef2f78.xz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+52720fcb44cb7f79c0cd@syzkaller.appspotmail.com ====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Tainted: G L ------------------------------------------------------ syz.5.6856/28306 is trying to acquire lock: ffffffff8f9eb728 (gadget_subsys.su_mutex){+.+.}-{4:4}, at: uvcg_frame_dw_max_video_frame_buffer_size_store+0x114/0x370 drivers/usb/gadget/function/uvc_configfs.c:2033 but task is already holding lock: ffff88803523b070 (&p->frag_sem){++++}-{4:4}, at: flush_write_buffer fs/configfs/file.c:205 [inline] ffff88803523b070 (&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: -> #3 (&p->frag_sem){++++}-{4:4}: down_write_killable+0xa6/0x240 kernel/locking/rwsem.c:1643 configfs_rmdir+0x3b0/0x950 fs/configfs/dir.c:1534 vfs_rmdir+0x3e6/0x6a0 fs/namei.c:5381 filename_rmdir+0x292/0x520 fs/namei.c:5438 __do_sys_unlinkat fs/namei.c:5613 [inline] __se_sys_unlinkat+0x71/0x1a0 fs/namei.c:5606 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #2 (&sb->s_type->i_mutex_key#24){++++}-{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:1259 usbg_make_tpg+0x1f6/0x590 drivers/usb/gadget/function/f_tcm.c:1686 target_fabric_make_tpg+0xa8/0x6d0 drivers/target/target_core_fabric_configfs.c:939 configfs_mkdir+0x4f6/0x9e0 fs/configfs/dir.c:1360 vfs_mkdir+0x406/0x620 fs/namei.c:5276 filename_mkdirat+0x285/0x510 fs/namei.c:5309 __do_sys_mkdirat fs/namei.c:5330 [inline] __se_sys_mkdirat+0x35/0x150 fs/namei.c:5327 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #1 (&opts->dep_lock){+.+.}-{4:4}: __mutex_lock_common kernel/locking/mutex.c:646 [inline] __mutex_lock+0x19d/0x1550 kernel/locking/mutex.c:821 tcm_set_name+0x2b/0xd0 drivers/usb/gadget/function/f_tcm.c:2669 function_make+0x1a8/0x360 drivers/usb/gadget/configfs.c:636 configfs_mkdir+0x4f6/0x9e0 fs/configfs/dir.c:1360 vfs_mkdir+0x406/0x620 fs/namei.c:5276 filename_mkdirat+0x285/0x510 fs/namei.c:5309 __do_sys_mkdirat fs/namei.c:5330 [inline] __se_sys_mkdirat+0x35/0x150 fs/namei.c:5327 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #0 (gadget_subsys.su_mutex){+.+.}-{4:4}: 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+0x1520/0x2cf0 kernel/locking/lockdep.c:5237 lock_acquire+0x106/0x350 kernel/locking/lockdep.c:5868 __mutex_lock_common kernel/locking/mutex.c:646 [inline] __mutex_lock+0x19d/0x1550 kernel/locking/mutex.c:821 uvcg_frame_dw_max_video_frame_buffer_size_store+0x114/0x370 drivers/usb/gadget/function/uvc_configfs.c:2033 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:63 [inline] do_syscall_64+0x174/0x580 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: gadget_subsys.su_mutex --> &sb->s_type->i_mutex_key#24 --> &p->frag_sem Possible unsafe locking scenario: CPU0 CPU1 ---- ---- rlock(&p->frag_sem); lock(&sb->s_type->i_mutex_key#24); lock(&p->frag_sem); lock(gadget_subsys.su_mutex); *** DEADLOCK *** 4 locks held by syz.5.6856/28306: #0: ffff888078c67cf0 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x246/0x320 fs/file.c:1259 #1: ffff88801d71a450 (sb_writers#12){.+.+}-{0:0}, at: file_start_write include/linux/fs.h:2733 [inline] #1: ffff88801d71a450 (sb_writers#12){.+.+}-{0:0}, at: vfs_write+0x22b/0xba0 fs/read_write.c:683 #2: ffff88807f11de80 (&buffer->mutex){+.+.}-{4:4}, at: configfs_write_iter+0x7e/0x430 fs/configfs/file.c:226 #3: ffff88803523b070 (&p->frag_sem){++++}-{4:4}, at: flush_write_buffer fs/configfs/file.c:205 [inline] #3: ffff88803523b070 (&p->frag_sem){++++}-{4:4}, at: configfs_write_iter+0x238/0x430 fs/configfs/file.c:229 stack backtrace: CPU: 0 UID: 0 PID: 28306 Comm: syz.5.6856 Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026 Call Trace: dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120 print_circular_bug+0x2e1/0x300 kernel/locking/lockdep.c:2043 check_noncircular+0x12e/0x150 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+0x1520/0x2cf0 kernel/locking/lockdep.c:5237 lock_acquire+0x106/0x350 kernel/locking/lockdep.c:5868 __mutex_lock_common kernel/locking/mutex.c:646 [inline] __mutex_lock+0x19d/0x1550 kernel/locking/mutex.c:821 uvcg_frame_dw_max_video_frame_buffer_size_store+0x114/0x370 drivers/usb/gadget/function/uvc_configfs.c:2033 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:63 [inline] do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f451779e0d9 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:00007f451858a028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 00007f4517a25fa0 RCX: 00007f451779e0d9 RDX: 0000000000000004 RSI: 00002000000006c0 RDI: 0000000000000004 RBP: 00007f4517835024 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f4517a26038 R14: 00007f4517a25fa0 R15: 00007ffd3ad99718 --- 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