From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-oi1-f207.google.com (mail-oi1-f207.google.com [209.85.167.207]) (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 AE2E35464C for ; Mon, 10 Aug 2026 00:13:26 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.167.207 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786320808; cv=none; b=u0MFUdJWn6/e1Ud36RSvt2oKqZrxjH1oKd1c5Q69SjbiBiUEKVnDLs9STFvFxscjn++hUv+TBjW3116hNrNRs9reCfVlLI4LuHAnsA3qwFiGnqsqOJU1fHWZoNhSTIjrf6mscXAO4pSoGWcAQO11j1QUgzRhaeMs0EpHOFQXWy8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786320808; c=relaxed/simple; bh=QWneyd1QSrXOGzQjw8f5EJNHhPN2t8GFQZtp3hBokwY=; h=MIME-Version:Date:Message-ID:Subject:From:To:Content-Type; b=FiU3f4DyvQHIAYGfc6PlbrkAMg2/quz6yGlOLi2rCAaJnlZmBoqnWbP39CLhCBNaUfo4iiFJPmbAzP4IcCXBD2zjFROav5L6t6TDhw1i7QOom9HqK1v8125XhCgzOsXHov/Vhzq178VZAXUuYp7Xh556qUFF49kLtNAyY/kyXFg= 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=209.85.167.207 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-oi1-f207.google.com with SMTP id 5614622812f47-4a416619e8dso2481807b6e.1 for ; Sun, 09 Aug 2026 17:13:26 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1786320805; x=1786925605; 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=ZBpe7+1TmfU8yVIQXgvY0XQ76keO4y24JiIBhOaZl8o=; b=NzF24mlafin1WQ4xE5/asHeXd6f776wKXHnPr1BfIfhzQtsZWn55G0k7TH75l/jj6O JP8PSnzPuqcgk/wgU5Rr9N6AVK3IzEjg2apfl6hMxAEnnA6d8YGPooOWl2SfN2HagJW1 JJfAYpNCoK1TS3XF4r/tIBXBG8AiCKVsi2vpaf2XarSUjkUUOQmh3A619n/F9tMJjH8u kTPEq6b/qGAqaC2wgAswfwYHGTLSm5sgERh2PTgd8jIjVZ+FbwbbeNX6SWBoZXPPCabA Q7vNWTTwixHzR8bvaEVK8vkeGrzTl3eviAOZ7Cn2STRZIDV/wQAZKMmiZ4qJSCYnSRkk IryA== X-Forwarded-Encrypted: i=1; AHgh+RoCYBF6fevdcE9I9jg4WI3oN+HE9z5rAJF+CayBWq+wVBlhCSlQ3Dwbi4oUVvTrnas+wA6dyLrlgDhODN8=@vger.kernel.org X-Gm-Message-State: AOJu0YygvaK0J11PzotgfO0dkP5yKhUrCdzSO4JOa+euzF0S1rmHTTyF 0C2v1wdR+xPewnYnOPVrhek5EuQLp2zdaGD+xeLKJh3PVzyrovA4hTx3+EzwBzVE2JvkL4A+M7t QQowYS7ZdlcFzJTbRDJs0rz6x9KyK+jw8ixWA7+E1LOMdXeA7k4IGzSNMac0= Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Received: by 2002:a05:6808:2381:b0:492:c9a4:2104 with SMTP id 5614622812f47-4b1af83fae5mr7830635b6e.10.1786320805648; Sun, 09 Aug 2026 17:13:25 -0700 (PDT) Date: Sun, 09 Aug 2026 17:13:25 -0700 X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <6a7917a5.b50370da.49fe0.0047.GAE@google.com> Subject: [syzbot] [usb?] possible deadlock in tcm_register_callback From: syzbot To: gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org, linux-usb@vger.kernel.org, syzkaller-bugs@googlegroups.com Content-Type: text/plain; charset="UTF-8" Hello, syzbot found the following issue on: HEAD commit: 848acc8ffe1b Merge tag 'fsverity-for-linus' of git://git.k.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=1113b649580000 kernel config: https://syzkaller.appspot.com/x/.config?x=145fa60d73086782 dashboard link: https://syzkaller.appspot.com/bug?extid=642d0d809d2c72babdd2 compiler: gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44 Unfortunately, I don't have any reproducer for this issue yet. Downloadable assets: disk image: https://storage.googleapis.com/syzbot-assets/32c9dc084aaa/disk-848acc8f.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/b7604244b0a9/vmlinux-848acc8f.xz kernel image: https://storage.googleapis.com/syzbot-assets/4cd321f6fe47/bzImage-848acc8f.xz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+642d0d809d2c72babdd2@syzkaller.appspotmail.com ====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Not tainted ------------------------------------------------------ syz.2.189/7749 is trying to acquire lock: ffff8880550c4118 (&opts->dep_lock){+.+.}-{4:4}, at: tcm_register_callback+0x1f/0x70 drivers/usb/gadget/function/f_tcm.c:2625 but task is already holding lock: ffff8880533c7070 (&p->frag_sem){++++}-{4:4}, at: flush_write_buffer fs/configfs/file.c:205 [inline] ffff8880533c7070 (&p->frag_sem){++++}-{4:4}, at: configfs_write_iter+0x218/0x4e0 fs/configfs/file.c:229 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (&p->frag_sem){++++}-{4:4}: lock_acquire kernel/locking/lockdep.c:5868 [inline] lock_acquire+0x1b9/0x370 kernel/locking/lockdep.c:5825 down_write_killable+0x93/0x250 kernel/locking/rwsem.c:1643 configfs_rmdir+0x3fa/0x950 fs/configfs/dir.c:1534 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] __x64_sys_rmdir+0x46/0x70 fs/namei.c:5458 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #1 (&sb->s_type->i_mutex_key#24){++++}-{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_mkdirat fs/namei.c:5330 [inline] __se_sys_mkdirat fs/namei.c:5327 [inline] __x64_sys_mkdirat+0x89/0xc0 fs/namei.c:5327 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #0 (&opts->dep_lock){+.+.}-{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 __mutex_lock_common kernel/locking/mutex.c:646 [inline] __mutex_lock+0x1a4/0x1bd0 kernel/locking/mutex.c:821 tcm_register_callback+0x1f/0x70 drivers/usb/gadget/function/f_tcm.c:2625 usbg_attach drivers/usb/gadget/function/f_tcm.c:2649 [inline] usbg_enable_tpg+0x95/0x160 drivers/usb/gadget/function/f_tcm.c:1825 target_tpg_enable+0x1fc/0x5d0 drivers/target/target_core_tpg.c:481 target_fabric_tpg_base_enable_store+0x162/0x190 drivers/target/target_core_fabric_configfs.c:840 flush_write_buffer fs/configfs/file.c:207 [inline] configfs_write_iter+0x302/0x4e0 fs/configfs/file.c:229 new_sync_write fs/read_write.c:595 [inline] vfs_write+0x6ac/0x1050 fs/read_write.c:687 ksys_write+0x12a/0x250 fs/read_write.c:739 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x115/0x870 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: &opts->dep_lock --> &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(&opts->dep_lock); *** DEADLOCK *** 4 locks held by syz.2.189/7749: #0: ffff888021776ef0 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x2aa/0x380 fs/file.c:1259 #1: ffff88801e736450 (sb_writers#13){.+.+}-{0:0}, at: ksys_write+0x12a/0x250 fs/read_write.c:739 #2: ffff88802bb2dc80 (&buffer->mutex){+.+.}-{4:4}, at: configfs_write_iter+0x76/0x4e0 fs/configfs/file.c:226 #3: ffff8880533c7070 (&p->frag_sem){++++}-{4:4}, at: flush_write_buffer fs/configfs/file.c:205 [inline] #3: ffff8880533c7070 (&p->frag_sem){++++}-{4:4}, at: configfs_write_iter+0x218/0x4e0 fs/configfs/file.c:229 stack backtrace: CPU: 0 UID: 0 PID: 7749 Comm: syz.2.189 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026 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 __mutex_lock_common kernel/locking/mutex.c:646 [inline] __mutex_lock+0x1a4/0x1bd0 kernel/locking/mutex.c:821 tcm_register_callback+0x1f/0x70 drivers/usb/gadget/function/f_tcm.c:2625 usbg_attach drivers/usb/gadget/function/f_tcm.c:2649 [inline] usbg_enable_tpg+0x95/0x160 drivers/usb/gadget/function/f_tcm.c:1825 target_tpg_enable+0x1fc/0x5d0 drivers/target/target_core_tpg.c:481 target_fabric_tpg_base_enable_store+0x162/0x190 drivers/target/target_core_fabric_configfs.c:840 flush_write_buffer fs/configfs/file.c:207 [inline] configfs_write_iter+0x302/0x4e0 fs/configfs/file.c:229 new_sync_write fs/read_write.c:595 [inline] vfs_write+0x6ac/0x1050 fs/read_write.c:687 ksys_write+0x12a/0x250 fs/read_write.c:739 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f72db79e019 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:00007f72dc5e0028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 00007f72dba25fa0 RCX: 00007f72db79e019 RDX: 0000000000000001 RSI: 00002000000009c0 RDI: 0000000000000007 RBP: 00007f72db83500c R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f72dba26038 R14: 00007f72dba25fa0 R15: 00007ffdfd368f88 UDC core: g1: couldn't find an available UDC or it's busy --- 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