====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Tainted: G L ------------------------------------------------------ syz.0.928/9134 is trying to acquire lock: ffffffff903fb7e8 (gadget_subsys.su_mutex){+.+.}-{4:4}, at: uvcg_streaming_header_allow_link+0x7c/0x650 drivers/usb/gadget/function/uvc_configfs.c:1750 but task is already holding lock: ffff8880396ab0c0 (&sb->s_type->i_mutex_key#24){++++}-{4:4}, at: inode_lock include/linux/fs.h:1024 [inline] ffff8880396ab0c0 (&sb->s_type->i_mutex_key#24){++++}-{4:4}, at: configfs_symlink+0x452/0x1340 fs/configfs/symlink.c:201 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #3 (&sb->s_type->i_mutex_key#24){++++}-{4:4}: lock_acquire kernel/locking/lockdep.c:5942 [inline] lock_acquire+0x1d1/0x380 kernel/locking/lockdep.c:5899 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:1268 usbg_make_tpg+0x251/0x610 drivers/usb/gadget/function/f_tcm.c:1692 target_fabric_make_tpg+0xab/0x8c0 drivers/target/target_core_fabric_configfs.c:947 configfs_mkdir+0x525/0xd40 fs/configfs/dir.c:1369 vfs_mkdir+0x364/0x850 fs/namei.c:5410 filename_mkdirat+0x48b/0x5e0 fs/namei.c:5443 __do_sys_mkdir fs/namei.c:5470 [inline] __se_sys_mkdir fs/namei.c:5467 [inline] __x64_sys_mkdir+0x6b/0x90 fs/namei.c:5467 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline] do_syscall_64+0x123/0x790 arch/x86/entry/syscall_64.c:84 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #2 (tpg_instances_lock){+.+.}-{4:4}: lock_acquire kernel/locking/lockdep.c:5942 [inline] lock_acquire+0x1d1/0x380 kernel/locking/lockdep.c:5899 __mutex_lock_common kernel/locking/mutex.c:646 [inline] __mutex_lock+0x1a4/0x1bd0 kernel/locking/mutex.c:821 tcm_alloc_inst+0x5f/0x1e0 drivers/usb/gadget/function/f_tcm.c:2687 try_get_usb_function_instance+0x136/0x1f0 drivers/usb/gadget/functions.c:28 usb_get_function_instance+0x16/0x70 drivers/usb/gadget/functions.c:44 function_make+0x18c/0x3f0 drivers/usb/gadget/configfs.c:626 configfs_mkdir+0x525/0xd40 fs/configfs/dir.c:1369 vfs_mkdir+0x364/0x850 fs/namei.c:5410 filename_mkdirat+0x48b/0x5e0 fs/namei.c:5443 __do_sys_mkdir fs/namei.c:5470 [inline] __se_sys_mkdir fs/namei.c:5467 [inline] __x64_sys_mkdir+0x6b/0x90 fs/namei.c:5467 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline] do_syscall_64+0x123/0x790 arch/x86/entry/syscall_64.c:84 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #1 (func_lock){+.+.}-{4:4}: lock_acquire kernel/locking/lockdep.c:5942 [inline] lock_acquire+0x1d1/0x380 kernel/locking/lockdep.c:5899 __mutex_lock_common kernel/locking/mutex.c:646 [inline] __mutex_lock+0x1a4/0x1bd0 kernel/locking/mutex.c:821 try_get_usb_function_instance+0x26/0x1f0 drivers/usb/gadget/functions.c:18 usb_get_function_instance+0x16/0x70 drivers/usb/gadget/functions.c:44 function_make+0x18c/0x3f0 drivers/usb/gadget/configfs.c:626 configfs_mkdir+0x525/0xd40 fs/configfs/dir.c:1369 vfs_mkdir+0x364/0x850 fs/namei.c:5410 filename_mkdirat+0x48b/0x5e0 fs/namei.c:5443 __do_sys_mkdirat fs/namei.c:5464 [inline] __se_sys_mkdirat fs/namei.c:5461 [inline] __x64_sys_mkdirat+0x89/0xc0 fs/namei.c:5461 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline] do_syscall_64+0x123/0x790 arch/x86/entry/syscall_64.c:84 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #0 (gadget_subsys.su_mutex){+.+.}-{4:4}: check_prev_add+0xeb/0xe60 kernel/locking/lockdep.c:3209 check_prevs_add kernel/locking/lockdep.c:3328 [inline] validate_chain kernel/locking/lockdep.c:3952 [inline] __lock_acquire+0x1528/0x1f40 kernel/locking/lockdep.c:5288 lock_acquire kernel/locking/lockdep.c:5942 [inline] lock_acquire+0x1d1/0x380 kernel/locking/lockdep.c:5899 __mutex_lock_common kernel/locking/mutex.c:646 [inline] __mutex_lock+0x1a4/0x1bd0 kernel/locking/mutex.c:821 uvcg_streaming_header_allow_link+0x7c/0x650 drivers/usb/gadget/function/uvc_configfs.c:1750 configfs_symlink+0x695/0x1340 fs/configfs/symlink.c:211 vfs_symlink fs/namei.c:5794 [inline] vfs_symlink+0x178/0x4d0 fs/namei.c:5773 filename_symlinkat+0x2a6/0x560 fs/namei.c:5819 __do_sys_symlinkat fs/namei.c:5839 [inline] __se_sys_symlinkat fs/namei.c:5834 [inline] __x64_sys_symlinkat+0x9c/0xe0 fs/namei.c:5834 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline] do_syscall_64+0x123/0x790 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 --> tpg_instances_lock --> &sb->s_type->i_mutex_key#24 Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&sb->s_type->i_mutex_key#24); lock(tpg_instances_lock); lock(&sb->s_type->i_mutex_key#24); lock(gadget_subsys.su_mutex); *** DEADLOCK *** locks held by syz.0.928/9134: 2, last CPU#1: #0: ffff888024294460 (sb_writers#13){.+.+}-{0:0}, at: filename_create+0x10d/0x400 fs/namei.c:5085 #1: ffff8880396ab0c0 (&sb->s_type->i_mutex_key#24){++++}-{4:4}, at: inode_lock include/linux/fs.h:1024 [inline] #1: ffff8880396ab0c0 (&sb->s_type->i_mutex_key#24){++++}-{4:4}, at: configfs_symlink+0x452/0x1340 fs/configfs/symlink.c:201 stack backtrace: CPU: 1 UID: 0 PID: 9134 Comm: syz.0.928 Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP 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+0x178/0x1be kernel/locking/lockdep.c:2087 check_noncircular+0x146/0x160 kernel/locking/lockdep.c:2219 check_prev_add+0xeb/0xe60 kernel/locking/lockdep.c:3209 check_prevs_add kernel/locking/lockdep.c:3328 [inline] validate_chain kernel/locking/lockdep.c:3952 [inline] __lock_acquire+0x1528/0x1f40 kernel/locking/lockdep.c:5288 lock_acquire kernel/locking/lockdep.c:5942 [inline] lock_acquire+0x1d1/0x380 kernel/locking/lockdep.c:5899 __mutex_lock_common kernel/locking/mutex.c:646 [inline] __mutex_lock+0x1a4/0x1bd0 kernel/locking/mutex.c:821 uvcg_streaming_header_allow_link+0x7c/0x650 drivers/usb/gadget/function/uvc_configfs.c:1750 configfs_symlink+0x695/0x1340 fs/configfs/symlink.c:211 vfs_symlink fs/namei.c:5794 [inline] vfs_symlink+0x178/0x4d0 fs/namei.c:5773 filename_symlinkat+0x2a6/0x560 fs/namei.c:5819 __do_sys_symlinkat fs/namei.c:5839 [inline] __se_sys_symlinkat fs/namei.c:5834 [inline] __x64_sys_symlinkat+0x9c/0xe0 fs/namei.c:5834 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline] do_syscall_64+0x123/0x790 arch/x86/entry/syscall_64.c:84 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f0b97b9e159 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:00007f0b95df6028 EFLAGS: 00000246 ORIG_RAX: 000000000000010a RAX: ffffffffffffffda RBX: 00007f0b97e25fa0 RCX: 00007f0b97b9e159 RDX: 0000200000001600 RSI: ffffffffffffff9c RDI: 0000200000001500 RBP: 00007f0b97c3503b R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f0b97e26038 R14: 00007f0b97e25fa0 R15: 00007fff553d7e48