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.0.17/6485 is trying to acquire lock:
ffff888032a72390 (&gi->lock){+.+.}-{4:4}, at: unregister_gadget_item+0x31/0xd0 drivers/usb/gadget/configfs.c:2087

but task is already holding lock:
ffff88805984b1c8 (&opts->lock){+.+.}-{4:4}, at: fsg_lun_drop+0x36/0x270 drivers/usb/gadget/function/f_mass_storage.c:3357

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&opts->lock){+.+.}-{4:4}:
       __mutex_lock_common kernel/locking/mutex.c:646 [inline]
       __mutex_lock+0x19d/0x15e0 kernel/locking/mutex.c:821
       fsg_alloc+0x92/0x200 drivers/usb/gadget/function/f_mass_storage.c:3569
       usb_get_function+0x63/0xb0 drivers/usb/gadget/functions.c:61
       config_usb_cfg_link+0x148/0x260 drivers/usb/gadget/configfs.c:469
       configfs_symlink+0x59a/0x1030 fs/configfs/symlink.c:196
       vfs_symlink+0x18b/0x330 fs/namei.c:5794
       filename_symlinkat+0x1cd/0x410 fs/namei.c:5819
       __do_sys_symlinkat fs/namei.c:5839 [inline]
       __se_sys_symlinkat+0x4e/0x2b0 fs/namei.c:5834
       do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
       do_syscall_64+0xfe/0x470 arch/x86/entry/syscall_64.c:84
       entry_SYSCALL_64_after_hwframe+0x76/0x7e

-> #0 (&gi->lock){+.+.}-{4:4}:
       check_prev_add kernel/locking/lockdep.c:3181 [inline]
       check_prevs_add kernel/locking/lockdep.c:3300 [inline]
       validate_chain kernel/locking/lockdep.c:3924 [inline]
       __lock_acquire+0x16f7/0x2df0 kernel/locking/lockdep.c:5253
       lock_acquire+0x106/0x350 kernel/locking/lockdep.c:5886
       __mutex_lock_common kernel/locking/mutex.c:646 [inline]
       __mutex_lock+0x19d/0x15e0 kernel/locking/mutex.c:821
       unregister_gadget_item+0x31/0xd0 drivers/usb/gadget/configfs.c:2087
       fsg_lun_drop+0xa8/0x270 drivers/usb/gadget/function/f_mass_storage.c:3362
       client_drop_item fs/configfs/dir.c:970 [inline]
       configfs_rmdir+0x85f/0x950 fs/configfs/dir.c:1567
       vfs_rmdir+0x3e6/0x6a0 fs/namei.c:5515
       filename_rmdir+0x292/0x520 fs/namei.c:5572
       __do_sys_rmdir fs/namei.c:5595 [inline]
       __se_sys_rmdir+0x2e/0x140 fs/namei.c:5592
       do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
       do_syscall_64+0xfe/0x470 arch/x86/entry/syscall_64.c:84
       entry_SYSCALL_64_after_hwframe+0x76/0x7e

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 ***

locks held by syz.0.17/6485: 5, last CPU#1:
 #0: ffff88801cfd0460 (sb_writers#12){.+.+}-{0:0}, at: mnt_want_write+0x41/0x90 fs/namespace.c:494
 #1: ffff8880712c4600 (&sb->s_type->i_mutex_key#8/1){+.+.}-{4:4}, at: inode_lock_nested include/linux/fs.h:1070 [inline]
 #1: ffff8880712c4600 (&sb->s_type->i_mutex_key#8/1){+.+.}-{4:4}, at: __start_dirop fs/namei.c:2918 [inline]
 #1: ffff8880712c4600 (&sb->s_type->i_mutex_key#8/1){+.+.}-{4:4}, at: start_dirop fs/namei.c:2942 [inline]
 #1: ffff8880712c4600 (&sb->s_type->i_mutex_key#8/1){+.+.}-{4:4}, at: filename_rmdir+0x1cd/0x520 fs/namei.c:5565
 #2: ffff8880712c4f80 (&sb->s_type->i_mutex_key#24){+.+.}-{4:4}, at: inode_lock include/linux/fs.h:1025 [inline]
 #2: ffff8880712c4f80 (&sb->s_type->i_mutex_key#24){+.+.}-{4:4}, at: vfs_rmdir+0xf8/0x6a0 fs/namei.c:5500
 #3: ffffffff8f562ae8 (gadget_subsys.su_mutex){+.+.}-{4:4}, at: configfs_rmdir+0x5f0/0x950 fs/configfs/dir.c:1556
 #4: ffff88805984b1c8 (&opts->lock){+.+.}-{4:4}, at: fsg_lun_drop+0x36/0x270 drivers/usb/gadget/function/f_mass_storage.c:3357

stack backtrace:
CPU: 1 UID: 0 PID: 6485 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_circular_bug+0x2e8/0x300 kernel/locking/lockdep.c:2059
 check_noncircular+0x12e/0x150 kernel/locking/lockdep.c:2191
 check_prev_add kernel/locking/lockdep.c:3181 [inline]
 check_prevs_add kernel/locking/lockdep.c:3300 [inline]
 validate_chain kernel/locking/lockdep.c:3924 [inline]
 __lock_acquire+0x16f7/0x2df0 kernel/locking/lockdep.c:5253
 lock_acquire+0x106/0x350 kernel/locking/lockdep.c:5886
 __mutex_lock_common kernel/locking/mutex.c:646 [inline]
 __mutex_lock+0x19d/0x15e0 kernel/locking/mutex.c:821
 unregister_gadget_item+0x31/0xd0 drivers/usb/gadget/configfs.c:2087
 fsg_lun_drop+0xa8/0x270 drivers/usb/gadget/function/f_mass_storage.c:3362
 client_drop_item fs/configfs/dir.c:970 [inline]
 configfs_rmdir+0x85f/0x950 fs/configfs/dir.c:1567
 vfs_rmdir+0x3e6/0x6a0 fs/namei.c:5515
 filename_rmdir+0x292/0x520 fs/namei.c:5572
 __do_sys_rmdir fs/namei.c:5595 [inline]
 __se_sys_rmdir+0x2e/0x140 fs/namei.c:5592
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0xfe/0x470 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x76/0x7e
RIP: 0033:0x7f00d3f9e0d9
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:00007f00d4d9c028 EFLAGS: 00000246 ORIG_RAX: 0000000000000054
RAX: ffffffffffffffda RBX: 00007f00d4225fa0 RCX: 00007f00d3f9e0d9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000200000000600
RBP: 00007f00d4035024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f00d4226038 R14: 00007f00d4225fa0 R15: 00007ffcc0e15b18
 </TASK>