Mass Storage Function, version: 2009/09/11
LUN: removable file: (no medium)
LUN: removable file: (no medium)
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.0.17/5939 is trying to acquire lock:
ffff888079372398 (&gi->lock){+.+.}-{3:3}, at: unregister_gadget_item+0x31/0xd0 drivers/usb/gadget/configfs.c:2085

but task is already holding lock:
ffff88802ff2e9d0 (&opts->lock){+.+.}-{3:3}, at: fsg_lun_drop+0x36/0x270 drivers/usb/gadget/function/f_mass_storage.c:3358

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&opts->lock){+.+.}-{3:3}:
       __mutex_lock_common kernel/locking/mutex.c:603 [inline]
       __mutex_lock+0x135/0xc80 kernel/locking/mutex.c:747
       fsg_alloc+0x92/0x200 drivers/usb/gadget/function/f_mass_storage.c:3570
       usb_get_function+0x5d/0xb0 drivers/usb/gadget/functions.c:61
       config_usb_cfg_link+0x148/0x250 drivers/usb/gadget/configfs.c:469
       configfs_symlink+0x5a5/0xfe0 fs/configfs/symlink.c:202
       vfs_symlink+0x138/0x2b0 fs/namei.c:4528
       do_symlinkat+0x1ba/0x400 fs/namei.c:4554
       __do_sys_symlinkat fs/namei.c:4570 [inline]
       __se_sys_symlinkat fs/namei.c:4567 [inline]
       __x64_sys_symlinkat+0x99/0xb0 fs/namei.c:4567
       do_syscall_x64 arch/x86/entry/common.c:46 [inline]
       do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

-> #0 (&gi->lock){+.+.}-{3:3}:
       check_prev_add kernel/locking/lockdep.c:3134 [inline]
       check_prevs_add kernel/locking/lockdep.c:3253 [inline]
       validate_chain kernel/locking/lockdep.c:3869 [inline]
       __lock_acquire+0x37ef/0x7d80 kernel/locking/lockdep.c:5137
       lock_acquire+0x19e/0x420 kernel/locking/lockdep.c:5754
       __mutex_lock_common kernel/locking/mutex.c:603 [inline]
       __mutex_lock+0x135/0xc80 kernel/locking/mutex.c:747
       unregister_gadget_item+0x31/0xd0 drivers/usb/gadget/configfs.c:2085
       fsg_lun_drop+0xa8/0x270 drivers/usb/gadget/function/f_mass_storage.c:3363
       client_drop_item fs/configfs/dir.c:962 [inline]
       configfs_rmdir+0x892/0x980 fs/configfs/dir.c:1567
       vfs_rmdir+0x352/0x4b0 fs/namei.c:4251
       do_rmdir+0x29f/0x590 fs/namei.c:4310
       __do_sys_rmdir fs/namei.c:4329 [inline]
       __se_sys_rmdir fs/namei.c:4327 [inline]
       __x64_sys_rmdir+0x49/0x50 fs/namei.c:4327
       do_syscall_x64 arch/x86/entry/common.c:46 [inline]
       do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

other info that might help us debug this:

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&opts->lock);
                               lock(&gi->lock);
                               lock(&opts->lock);
  lock(&gi->lock);

 *** DEADLOCK ***

5 locks held by syz.0.17/5939:
 #0: ffff888142688418 (sb_writers#13){.+.+}-{0:0}, at: mnt_want_write+0x41/0x90 fs/namespace.c:412
 #1: ffff88805f233910 (&sb->s_type->i_mutex_key#7/1){+.+.}-{3:3}, at: inode_lock_nested include/linux/fs.h:839 [inline]
 #1: ffff88805f233910 (&sb->s_type->i_mutex_key#7/1){+.+.}-{3:3}, at: do_rmdir+0x1c6/0x590 fs/namei.c:4298
 #2: ffff888076d22ef0 (&sb->s_type->i_mutex_key#20){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:804 [inline]
 #2: ffff888076d22ef0 (&sb->s_type->i_mutex_key#20){+.+.}-{3:3}, at: vfs_rmdir+0xee/0x4b0 fs/namei.c:4240
 #3: ffffffff8ddf69d0 (gadget_subsys.su_mutex){+.+.}-{3:3}, at: configfs_rmdir+0x63c/0x980 fs/configfs/dir.c:1556
 #4: ffff88802ff2e9d0 (&opts->lock){+.+.}-{3:3}, at: fsg_lun_drop+0x36/0x270 drivers/usb/gadget/function/f_mass_storage.c:3358

stack backtrace:
CPU: 1 PID: 5939 Comm: syz.0.17 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0x18c/0x250 lib/dump_stack.c:106
 check_noncircular+0x2fc/0x400 kernel/locking/lockdep.c:2187
 check_prev_add kernel/locking/lockdep.c:3134 [inline]
 check_prevs_add kernel/locking/lockdep.c:3253 [inline]
 validate_chain kernel/locking/lockdep.c:3869 [inline]
 __lock_acquire+0x37ef/0x7d80 kernel/locking/lockdep.c:5137
 lock_acquire+0x19e/0x420 kernel/locking/lockdep.c:5754
 __mutex_lock_common kernel/locking/mutex.c:603 [inline]
 __mutex_lock+0x135/0xc80 kernel/locking/mutex.c:747
 unregister_gadget_item+0x31/0xd0 drivers/usb/gadget/configfs.c:2085
 fsg_lun_drop+0xa8/0x270 drivers/usb/gadget/function/f_mass_storage.c:3363
 client_drop_item fs/configfs/dir.c:962 [inline]
 configfs_rmdir+0x892/0x980 fs/configfs/dir.c:1567
 vfs_rmdir+0x352/0x4b0 fs/namei.c:4251
 do_rmdir+0x29f/0x590 fs/namei.c:4310
 __do_sys_rmdir fs/namei.c:4329 [inline]
 __se_sys_rmdir fs/namei.c:4327 [inline]
 __x64_sys_rmdir+0x49/0x50 fs/namei.c:4327
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f26ad39e0d9
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:00007ffe635cbdf8 EFLAGS: 00000246 ORIG_RAX: 0000000000000054
RAX: ffffffffffffffda RBX: 00007f26ad625fa0 RCX: 00007f26ad39e0d9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000200000000600
RBP: 00007f26ad435024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f26ad625fac R14: 00007f26ad625fa0 R15: 00007f26ad625fa0
 </TASK>