======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Tainted: G             L     
------------------------------------------------------
syz.2.1093/13128 is trying to acquire lock:
ffffffff8fc0e648 (gadget_subsys.su_mutex){+.+.}-{4:4}, at: uvcg_format_bma_controls_show drivers/usb/gadget/function/uvc_configfs.c:1681 [inline]
ffffffff8fc0e648 (gadget_subsys.su_mutex){+.+.}-{4:4}, at: uvcg_mjpeg_bma_controls_show+0x4d/0x140 drivers/usb/gadget/function/uvc_configfs.c:2635

but task is already holding lock:
ffff888074dbf770 (&p->frag_sem){++++}-{4:4}, at: fill_read_buffer fs/configfs/file.c:66 [inline]
ffff888074dbf770 (&p->frag_sem){++++}-{4:4}, at: configfs_read_iter+0x1cc/0x620 fs/configfs/file.c:88

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #4 (&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:5515
       filename_rmdir+0x292/0x520 fs/namei.c:5572
       __do_sys_unlinkat fs/namei.c:5747 [inline]
       __se_sys_unlinkat+0x71/0x1a0 fs/namei.c:5740
       do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
       do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #3 (&sb->s_type->i_mutex_key#32){++++}-{4:4}:
       down_write+0x96/0x200 kernel/locking/rwsem.c:1631
       inode_lock include/linux/fs.h:1025 [inline]
       configfs_depend_item_unlocked+0x153/0x420 fs/configfs/dir.c:1259
       usbg_make_tpg+0x1e0/0x550 drivers/usb/gadget/function/f_tcm.c:1692
       target_fabric_make_tpg+0xa8/0x6d0 drivers/target/target_core_fabric_configfs.c:947
       configfs_mkdir+0x4f6/0x9e0 fs/configfs/dir.c:1360
       vfs_mkdir+0x40c/0x620 fs/namei.c:5410
       filename_mkdirat+0x285/0x510 fs/namei.c:5443
       __do_sys_mkdir fs/namei.c:5470 [inline]
       __se_sys_mkdir+0x34/0x150 fs/namei.c:5467
       do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
       do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #2 (tpg_instances_lock){+.+.}-{4:4}:
       __mutex_lock_common kernel/locking/mutex.c:646 [inline]
       __mutex_lock+0x19d/0x1550 kernel/locking/mutex.c:821
       tcm_alloc_inst+0x65/0x1a0 drivers/usb/gadget/function/f_tcm.c:2687
       try_get_usb_function_instance drivers/usb/gadget/functions.c:28 [inline]
       usb_get_function_instance+0xe3/0x2f0 drivers/usb/gadget/functions.c:44
       function_make+0x127/0x360 drivers/usb/gadget/configfs.c:626
       configfs_mkdir+0x4f6/0x9e0 fs/configfs/dir.c:1360
       vfs_mkdir+0x40c/0x620 fs/namei.c:5410
       filename_mkdirat+0x285/0x510 fs/namei.c:5443
       __do_sys_mkdir fs/namei.c:5470 [inline]
       __se_sys_mkdir+0x34/0x150 fs/namei.c:5467
       do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
       do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #1 (func_lock){+.+.}-{4:4}:
       __mutex_lock_common kernel/locking/mutex.c:646 [inline]
       __mutex_lock+0x19d/0x1550 kernel/locking/mutex.c:821
       try_get_usb_function_instance drivers/usb/gadget/functions.c:18 [inline]
       usb_get_function_instance+0x2e/0x2f0 drivers/usb/gadget/functions.c:44
       function_make+0x127/0x360 drivers/usb/gadget/configfs.c:626
       configfs_mkdir+0x4f6/0x9e0 fs/configfs/dir.c:1360
       vfs_mkdir+0x40c/0x620 fs/namei.c:5410
       filename_mkdirat+0x285/0x510 fs/namei.c:5443
       __do_sys_mkdir fs/namei.c:5470 [inline]
       __se_sys_mkdir+0x34/0x150 fs/namei.c:5467
       do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
       do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #0 (gadget_subsys.su_mutex){+.+.}-{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+0x1520/0x2cf0 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/0x1550 kernel/locking/mutex.c:821
       uvcg_format_bma_controls_show drivers/usb/gadget/function/uvc_configfs.c:1681 [inline]
       uvcg_mjpeg_bma_controls_show+0x4d/0x140 drivers/usb/gadget/function/uvc_configfs.c:2635
       fill_read_buffer fs/configfs/file.c:68 [inline]
       configfs_read_iter+0x2b7/0x620 fs/configfs/file.c:88
       __kernel_read+0x4ca/0x960 fs/read_write.c:532
       integrity_kernel_read+0x89/0xd0 security/integrity/iint.c:28
       ima_calc_file_hash_tfm security/integrity/ima/ima_crypto.c:222 [inline]
       ima_calc_file_hash+0x451/0x890 security/integrity/ima/ima_crypto.c:280
       ima_collect_measurement+0x51b/0xa00 security/integrity/ima/ima_api.c:300
       process_measurement+0x1272/0x1c10 security/integrity/ima/ima_main.c:425
       ima_file_check+0xe1/0x130 security/integrity/ima/ima_main.c:685
       security_file_post_open+0xb3/0x260 security/security.c:2755
       do_open fs/namei.c:4839 [inline]
       path_openat+0x1485/0x1d60 fs/namei.c:5000
       do_file_open+0x23e/0x4a0 fs/namei.c:5029
       do_sys_openat2+0x115/0x200 fs/open.c:1417
       do_sys_open fs/open.c:1423 [inline]
       __do_sys_openat fs/open.c:1439 [inline]
       __se_sys_openat fs/open.c:1434 [inline]
       __x64_sys_openat+0x138/0x170 fs/open.c:1434
       do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
       do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84
       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#32 --> &p->frag_sem

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  rlock(&p->frag_sem);
                               lock(&sb->s_type->i_mutex_key#32);
                               lock(&p->frag_sem);
  lock(gadget_subsys.su_mutex);

 *** DEADLOCK ***

locks held by syz.2.1093/13128: 3, last CPU#0:
 #0: ffff888074cfc798 (&ima_iint_mutex_key[depth]){+.+.}-{4:4}, at: process_measurement+0x7d0/0x1c10 security/integrity/ima/ima_main.c:319
 #1: ffff8880550a0280 (&buffer->mutex){+.+.}-{4:4}, at: configfs_read_iter+0x70/0x620 fs/configfs/file.c:86
 #2: ffff888074dbf770 (&p->frag_sem){++++}-{4:4}, at: fill_read_buffer fs/configfs/file.c:66 [inline]
 #2: ffff888074dbf770 (&p->frag_sem){++++}-{4:4}, at: configfs_read_iter+0x1cc/0x620 fs/configfs/file.c:88

stack backtrace:
CPU: 0 UID: 0 PID: 13128 Comm: syz.2.1093 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:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_circular_bug+0x2e1/0x300 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+0x1520/0x2cf0 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/0x1550 kernel/locking/mutex.c:821
 uvcg_format_bma_controls_show drivers/usb/gadget/function/uvc_configfs.c:1681 [inline]
 uvcg_mjpeg_bma_controls_show+0x4d/0x140 drivers/usb/gadget/function/uvc_configfs.c:2635
 fill_read_buffer fs/configfs/file.c:68 [inline]
 configfs_read_iter+0x2b7/0x620 fs/configfs/file.c:88
 __kernel_read+0x4ca/0x960 fs/read_write.c:532
 integrity_kernel_read+0x89/0xd0 security/integrity/iint.c:28
 ima_calc_file_hash_tfm security/integrity/ima/ima_crypto.c:222 [inline]
 ima_calc_file_hash+0x451/0x890 security/integrity/ima/ima_crypto.c:280
 ima_collect_measurement+0x51b/0xa00 security/integrity/ima/ima_api.c:300
 process_measurement+0x1272/0x1c10 security/integrity/ima/ima_main.c:425
 ima_file_check+0xe1/0x130 security/integrity/ima/ima_main.c:685
 security_file_post_open+0xb3/0x260 security/security.c:2755
 do_open fs/namei.c:4839 [inline]
 path_openat+0x1485/0x1d60 fs/namei.c:5000
 do_file_open+0x23e/0x4a0 fs/namei.c:5029
 do_sys_openat2+0x115/0x200 fs/open.c:1417
 do_sys_open fs/open.c:1423 [inline]
 __do_sys_openat fs/open.c:1439 [inline]
 __se_sys_openat fs/open.c:1434 [inline]
 __x64_sys_openat+0x138/0x170 fs/open.c:1434
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f289579e0d9
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:00007f28966cd028 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007f2895a26090 RCX: 00007f289579e0d9
RDX: 0000000000000002 RSI: 00002000000002c0 RDI: ffffffffffffff9c
RBP: 00007f2895835024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f2895a26128 R14: 00007f2895a26090 R15: 00007ffe223ed878
 </TASK>