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AHgh+Rrbr0ADuRm4O+z0RZiT/mrEzgZpvZTIsRNpzR1Q3djTvzW8RwtlMfHxL9jQE1BSTQ/X/8kuE8HV7Nl5R4s6@vger.kernel.org X-Gm-Message-State: AOJu0Ywsxd32SV75Ni4k5fWMmjfFxGwvR4pz7ruuGDK7GmMpVQY/2ovH dJ/rfqRt+0S7idu+UiLS5l7FrTz2d5LyhlguZTen10aJZLRrAr4NGd76pHmt4RBSxh7pVgu7bp3 etN7xQiBy0lsQPNU2284OcHzJNdjblaF4RI0sJ3hFs04NzWNg934iY7q+yuQ= Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Received: by 2002:a05:6808:1407:b0:49a:72a:4e45 with SMTP id 5614622812f47-4ad5bbe0d65mr3076496b6e.39.1785320362465; Wed, 29 Jul 2026 03:19:22 -0700 (PDT) Date: Wed, 29 Jul 2026 03:19:22 -0700 In-Reply-To: <6a68af31.073198cf.94f0f.0048.GAE@google.com> X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <6a69d3aa.cf6637f5.2f8219.0031.GAE@google.com> Subject: Re: [syzbot] [fs?] possible deadlock in configfs_rmdir 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" syzbot has found a reproducer for the following issue on: HEAD commit: fc02acf6ac0c Merge tag 'platform-drivers-x86-v7.2-4' of gi.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=15db5632580000 kernel config: https://syzkaller.appspot.com/x/.config?x=145fa60d73086782 dashboard link: https://syzkaller.appspot.com/bug?extid=c9f9d646b08f3b6032fe compiler: gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44 syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1496003e580000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=142017b1580000 Downloadable assets: disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-fc02acf6.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/eca05900a79c/vmlinux-fc02acf6.xz kernel image: https://storage.googleapis.com/syzbot-assets/e655b72e0b5f/bzImage-fc02acf6.xz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+c9f9d646b08f3b6032fe@syzkaller.appspotmail.com ====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Not tainted ------------------------------------------------------ syz.0.18/5928 is trying to acquire lock: ffffffff901d0908 (gadget_subsys.su_mutex){+.+.}-{4:4}, at: configfs_rmdir+0x5ae/0x950 fs/configfs/dir.c:1556 but task is already holding lock: ffff88803aa6f800 (&sb->s_type->i_mutex_key#24){+.+.}-{4:4}, at: inode_lock include/linux/fs.h:1024 [inline] ffff88803aa6f800 (&sb->s_type->i_mutex_key#24){+.+.}-{4:4}, at: vfs_rmdir fs/namei.c:5366 [inline] ffff88803aa6f800 (&sb->s_type->i_mutex_key#24){+.+.}-{4:4}, at: vfs_rmdir+0xed/0x8a0 fs/namei.c:5354 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (&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_mkdir fs/namei.c:5336 [inline] __se_sys_mkdir fs/namei.c:5333 [inline] __x64_sys_mkdir+0x6b/0x90 fs/namei.c:5333 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 (&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] __x64_sys_mkdir+0x6b/0x90 fs/namei.c:5333 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 (gadget_subsys.su_mutex){+.+.}-{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 configfs_rmdir+0x5ae/0x950 fs/configfs/dir.c:1556 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_unlinkat fs/namei.c:5613 [inline] __se_sys_unlinkat fs/namei.c:5606 [inline] __x64_sys_unlinkat+0xf5/0x130 fs/namei.c:5606 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: gadget_subsys.su_mutex --> &opts->dep_lock --> &sb->s_type->i_mutex_key#24 Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&sb->s_type->i_mutex_key#24); lock(&opts->dep_lock); lock(&sb->s_type->i_mutex_key#24); lock(gadget_subsys.su_mutex); *** DEADLOCK *** 3 locks held by syz.0.18/5928: #0: ffff888023d44450 (sb_writers#13){.+.+}-{0:0}, at: filename_rmdir+0x1ff/0x5c0 fs/namei.c:5427 #1: ffff888047c6e9c0 (&default_group_class[depth - 1]#2/1){+.+.}-{4:4}, at: inode_lock_nested include/linux/fs.h:1069 [inline] #1: ffff888047c6e9c0 (&default_group_class[depth - 1]#2/1){+.+.}-{4:4}, at: __start_dirop fs/namei.c:2918 [inline] #1: ffff888047c6e9c0 (&default_group_class[depth - 1]#2/1){+.+.}-{4:4}, at: start_dirop fs/namei.c:2942 [inline] #1: ffff888047c6e9c0 (&default_group_class[depth - 1]#2/1){+.+.}-{4:4}, at: filename_rmdir+0x258/0x5c0 fs/namei.c:5431 #2: ffff88803aa6f800 (&sb->s_type->i_mutex_key#24){+.+.}-{4:4}, at: inode_lock include/linux/fs.h:1024 [inline] #2: ffff88803aa6f800 (&sb->s_type->i_mutex_key#24){+.+.}-{4:4}, at: vfs_rmdir fs/namei.c:5366 [inline] #2: ffff88803aa6f800 (&sb->s_type->i_mutex_key#24){+.+.}-{4:4}, at: vfs_rmdir+0xed/0x8a0 fs/namei.c:5354 stack backtrace: CPU: 3 UID: 0 PID: 5928 Comm: syz.0.18 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 __mutex_lock_common kernel/locking/mutex.c:646 [inline] __mutex_lock+0x1a4/0x1bd0 kernel/locking/mutex.c:821 configfs_rmdir+0x5ae/0x950 fs/configfs/dir.c:1556 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_unlinkat fs/namei.c:5613 [inline] __se_sys_unlinkat fs/namei.c:5606 [inline] __x64_sys_unlinkat+0xf5/0x130 fs/namei.c:5606 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: 0033:0x7f838c39de99 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:00007ffd033e6618 EFLAGS: 00000246 ORIG_RAX: 0000000000000107 RAX: ffffffffffffffda RBX: 00007f838c625fa0 RCX: 00007f838c39de99 RDX: 0000000000000200 RSI: 0000200000000480 RDI: ffffffffffffff9c RBP: 00007f838c433eaf R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f838c625fac R14: 00007f838c625fa0 R15: 00007f838c625fa0 --- If you want syzbot to run the reproducer, reply with: #syz test: git://repo/address.git branch-or-commit-hash If you attach or paste a git patch, syzbot will apply it before testing.