====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Tainted: G L ------------------------------------------------------ syz.0.3633/17729 is trying to acquire lock: ffffffff901d2b48 (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: ffff88802ac93a40 (&sb->s_type->i_mutex_key#24){++++}-{4:4}, at: inode_lock include/linux/fs.h:1024 [inline] ffff88802ac93a40 (&sb->s_type->i_mutex_key#24){++++}-{4:4}, at: configfs_symlink+0x3c0/0x11f0 fs/configfs/symlink.c:186 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_mkdirat fs/namei.c:5330 [inline] __se_sys_mkdirat fs/namei.c:5327 [inline] __ia32_sys_mkdirat+0x88/0xc0 fs/namei.c:5327 do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:83 [inline] __do_fast_syscall_32+0xe7/0x970 arch/x86/entry/syscall_32.c:307 do_fast_syscall_32+0x32/0x70 arch/x86/entry/syscall_32.c:332 entry_SYSENTER_compat_after_hwframe+0x84/0x8e -> #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:2540 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_mkdirat fs/namei.c:5330 [inline] __se_sys_mkdirat fs/namei.c:5327 [inline] __ia32_sys_mkdirat+0x88/0xc0 fs/namei.c:5327 do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:83 [inline] __do_fast_syscall_32+0xe7/0x970 arch/x86/entry/syscall_32.c:307 do_fast_syscall_32+0x32/0x70 arch/x86/entry/syscall_32.c:332 entry_SYSENTER_compat_after_hwframe+0x84/0x8e -> #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 uvcg_streaming_header_allow_link+0x7c/0x650 drivers/usb/gadget/function/uvc_configfs.c:1750 configfs_symlink+0x540/0x11f0 fs/configfs/symlink.c:196 vfs_symlink fs/namei.c:5660 [inline] vfs_symlink+0x178/0x4d0 fs/namei.c:5639 filename_symlinkat+0x2a6/0x560 fs/namei.c:5685 __do_sys_symlink fs/namei.c:5712 [inline] __se_sys_symlink fs/namei.c:5708 [inline] __ia32_sys_symlink+0x78/0xb0 fs/namei.c:5708 do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:83 [inline] __do_fast_syscall_32+0xe7/0x970 arch/x86/entry/syscall_32.c:307 do_fast_syscall_32+0x32/0x70 arch/x86/entry/syscall_32.c:332 entry_SYSENTER_compat_after_hwframe+0x84/0x8e 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 *** 2 locks held by syz.0.3633/17729: #0: ffff888022038450 (sb_writers#12){.+.+}-{0:0}, at: filename_create+0x10d/0x400 fs/namei.c:4948 #1: ffff88802ac93a40 (&sb->s_type->i_mutex_key#24){++++}-{4:4}, at: inode_lock include/linux/fs.h:1024 [inline] #1: ffff88802ac93a40 (&sb->s_type->i_mutex_key#24){++++}-{4:4}, at: configfs_symlink+0x3c0/0x11f0 fs/configfs/symlink.c:186 stack backtrace: CPU: 1 UID: 0 PID: 17729 Comm: syz.0.3633 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+0x178/0x1c7 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 uvcg_streaming_header_allow_link+0x7c/0x650 drivers/usb/gadget/function/uvc_configfs.c:1750 configfs_symlink+0x540/0x11f0 fs/configfs/symlink.c:196 vfs_symlink fs/namei.c:5660 [inline] vfs_symlink+0x178/0x4d0 fs/namei.c:5639 filename_symlinkat+0x2a6/0x560 fs/namei.c:5685 __do_sys_symlink fs/namei.c:5712 [inline] __se_sys_symlink fs/namei.c:5708 [inline] __ia32_sys_symlink+0x78/0xb0 fs/namei.c:5708 do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:83 [inline] __do_fast_syscall_32+0xe7/0x970 arch/x86/entry/syscall_32.c:307 do_fast_syscall_32+0x32/0x70 arch/x86/entry/syscall_32.c:332 entry_SYSENTER_compat_after_hwframe+0x84/0x8e RIP: 0023:0xf6feefec Code: Unable to access opcode bytes at 0xf6feefc2. RSP: 002b:00000000f53dd50c EFLAGS: 00000292 ORIG_RAX: 0000000000000053 RAX: ffffffffffffffda RBX: 0000000080001400 RCX: 0000000080001500 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000292 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000