====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Tainted: G L ------------------------------------------------------ syz.5.1374/12082 is trying to acquire lock: ffff888043f7ad20 (&ovl_i_mutex_dir_key[depth]){++++}-{4:4}, at: inode_lock_shared include/linux/fs.h:1044 [inline] ffff888043f7ad20 (&ovl_i_mutex_dir_key[depth]){++++}-{4:4}, at: lookup_slow+0x42/0x70 fs/namei.c:1931 but task is already holding lock: ffff88802a20b880 (&of->mutex){+.+.}-{4:4}, at: kernfs_fop_write_iter+0x2c2/0x5f0 fs/kernfs/file.c:343 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #4 (&of->mutex){+.+.}-{4:4}: __mutex_lock_common kernel/locking/mutex.c:646 [inline] __mutex_lock+0x1a4/0x1b10 kernel/locking/mutex.c:820 kernfs_seq_start+0x4f/0x2a0 fs/kernfs/file.c:172 seq_read_iter+0x2c1/0x1270 fs/seq_file.c:226 kernfs_fop_read_iter+0x46c/0x610 fs/kernfs/file.c:297 copy_splice_read+0x4ba/0xb90 fs/splice.c:362 do_splice_read fs/splice.c:980 [inline] do_splice_read+0x285/0x370 fs/splice.c:954 splice_file_to_pipe+0x82/0x120 fs/splice.c:1290 do_sendfile+0x366/0xe20 fs/read_write.c:1378 __do_compat_sys_sendfile fs/read_write.c:1454 [inline] __se_compat_sys_sendfile fs/read_write.c:1437 [inline] __ia32_compat_sys_sendfile+0x1e5/0x220 fs/read_write.c:1437 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 -> #3 (&p->lock){+.+.}-{4:4}: __mutex_lock_common kernel/locking/mutex.c:646 [inline] __mutex_lock+0x1a4/0x1b10 kernel/locking/mutex.c:820 seq_read_iter+0xe1/0x1270 fs/seq_file.c:183 kernfs_fop_read_iter+0x46c/0x610 fs/kernfs/file.c:297 copy_splice_read+0x4ba/0xb90 fs/splice.c:362 do_splice_read fs/splice.c:980 [inline] do_splice_read+0x285/0x370 fs/splice.c:954 splice_file_to_pipe+0x82/0x120 fs/splice.c:1290 do_sendfile+0x366/0xe20 fs/read_write.c:1378 __do_compat_sys_sendfile fs/read_write.c:1454 [inline] __se_compat_sys_sendfile fs/read_write.c:1437 [inline] __ia32_compat_sys_sendfile+0x1e5/0x220 fs/read_write.c:1437 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 -> #2 ( &pipe->mutex){+.+.}-{4:4}: __mutex_lock_common kernel/locking/mutex.c:646 [inline] __mutex_lock+0x1a4/0x1b10 kernel/locking/mutex.c:820 pipe_lock fs/pipe.c:91 [inline] pipe_lock+0x69/0x80 fs/pipe.c:88 iter_file_splice_write+0x1fd/0x10a0 fs/splice.c:682 do_splice_from fs/splice.c:936 [inline] do_splice+0x109c/0x1fd0 fs/splice.c:1349 __do_splice+0x33b/0x370 fs/splice.c:1431 __do_sys_splice fs/splice.c:1634 [inline] __se_sys_splice fs/splice.c:1616 [inline] __ia32_sys_splice+0x189/0x250 fs/splice.c:1616 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 (sb_writers#5){.+.+}-{0:0}: percpu_down_read_internal include/linux/percpu-rwsem.h:53 [inline] percpu_down_read_freezable include/linux/percpu-rwsem.h:83 [inline] __sb_start_write include/linux/fs/super.h:19 [inline] sb_start_write include/linux/fs/super.h:125 [inline] mnt_want_write+0x6f/0x450 fs/namespace.c:493 ovl_create_object+0x12b/0x3b0 fs/overlayfs/dir.c:706 lookup_open.isra.0+0xc47/0x11b0 fs/namei.c:4511 open_last_lookups fs/namei.c:4611 [inline] path_openat+0x2291/0x31a0 fs/namei.c:4855 do_file_open+0x20e/0x430 fs/namei.c:4887 do_sys_openat2+0x10d/0x1e0 fs/open.c:1364 do_sys_open fs/open.c:1370 [inline] __do_compat_sys_open fs/open.c:1423 [inline] __se_compat_sys_open fs/open.c:1421 [inline] __ia32_compat_sys_open+0xfe/0x1c0 fs/open.c:1421 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 (&ovl_i_mutex_dir_key[depth]){++++}-{4:4}: check_prev_add kernel/locking/lockdep.c:3165 [inline] check_prevs_add kernel/locking/lockdep.c:3284 [inline] validate_chain kernel/locking/lockdep.c:3908 [inline] __lock_acquire+0x14b8/0x2630 kernel/locking/lockdep.c:5237 lock_acquire kernel/locking/lockdep.c:5868 [inline] lock_acquire+0x1b1/0x370 kernel/locking/lockdep.c:5825 down_read+0x99/0x450 kernel/locking/rwsem.c:1568 inode_lock_shared include/linux/fs.h:1044 [inline] lookup_slow+0x42/0x70 fs/namei.c:1931 walk_component fs/namei.c:2278 [inline] lookup_last fs/namei.c:2785 [inline] path_lookupat+0x5e8/0xc40 fs/namei.c:2809 filename_lookup+0x202/0x590 fs/namei.c:2838 kern_path+0x37/0x50 fs/namei.c:3044 lookup_bdev+0xd8/0x280 block/bdev.c:1213 resume_store+0x1d6/0x460 kernel/power/hibernate.c:1306 kobj_attr_store+0x58/0x80 lib/kobject.c:840 sysfs_kf_write+0xf2/0x150 fs/sysfs/file.c:142 kernfs_fop_write_iter+0x3e0/0x5f0 fs/kernfs/file.c:352 new_sync_write fs/read_write.c:595 [inline] vfs_write+0x6ac/0x1070 fs/read_write.c:688 ksys_write+0x12a/0x250 fs/read_write.c:740 do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:83 [inline] do_int80_emulation+0x14b/0x720 arch/x86/entry/syscall_32.c:172 asm_int80_emulation+0x1a/0x20 arch/x86/include/asm/idtentry.h:621 other info that might help us debug this: Chain exists of: &ovl_i_mutex_dir_key[depth] --> &p->lock --> &of->mutex Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&of->mutex); lock(&p->lock); lock(&of->mutex); rlock(&ovl_i_mutex_dir_key[depth]); *** DEADLOCK *** 4 locks held by syz.5.1374/12082: #0: ffff88802a4b1970 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x2aa/0x380 fs/file.c:1261 #1: ffff888025030410 (sb_writers#7){.+.+}-{0:0}, at: ksys_write+0x12a/0x250 fs/read_write.c:740 #2: ffff88802a20b880 (&of->mutex){+.+.}-{4:4}, at: kernfs_fop_write_iter+0x2c2/0x5f0 fs/kernfs/file.c:343 #3: ffff88801cbdc0f8 (kn->active#66){.+.+}-{0:0}, at: kernfs_get_active_of fs/kernfs/file.c:80 [inline] #3: ffff88801cbdc0f8 (kn->active#66){.+.+}-{0:0}, at: kernfs_fop_write_iter+0x332/0x5f0 fs/kernfs/file.c:344 stack backtrace: CPU: 1 UID: 0 PID: 12082 Comm: syz.5.1374 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 kernel/locking/lockdep.c:3165 [inline] check_prevs_add kernel/locking/lockdep.c:3284 [inline] validate_chain kernel/locking/lockdep.c:3908 [inline] __lock_acquire+0x14b8/0x2630 kernel/locking/lockdep.c:5237 lock_acquire kernel/locking/lockdep.c:5868 [inline] lock_acquire+0x1b1/0x370 kernel/locking/lockdep.c:5825 down_read+0x99/0x450 kernel/locking/rwsem.c:1568 inode_lock_shared include/linux/fs.h:1044 [inline] lookup_slow+0x42/0x70 fs/namei.c:1931 walk_component fs/namei.c:2278 [inline] lookup_last fs/namei.c:2785 [inline] path_lookupat+0x5e8/0xc40 fs/namei.c:2809 filename_lookup+0x202/0x590 fs/namei.c:2838 kern_path+0x37/0x50 fs/namei.c:3044 lookup_bdev+0xd8/0x280 block/bdev.c:1213 resume_store+0x1d6/0x460 kernel/power/hibernate.c:1306 kobj_attr_store+0x58/0x80 lib/kobject.c:840 sysfs_kf_write+0xf2/0x150 fs/sysfs/file.c:142 kernfs_fop_write_iter+0x3e0/0x5f0 fs/kernfs/file.c:352 new_sync_write fs/read_write.c:595 [inline] vfs_write+0x6ac/0x1070 fs/read_write.c:688 ksys_write+0x12a/0x250 fs/read_write.c:740 do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:83 [inline] do_int80_emulation+0x14b/0x720 arch/x86/entry/syscall_32.c:172 asm_int80_emulation+0x1a/0x20 arch/x86/include/asm/idtentry.h:621 RIP: 0023:0xf71661ab Code: 57 56 53 8b 44 24 14 f6 00 08 75 23 8b 44 24 18 8b 5c 24 1c 8b 4c 24 20 8b 54 24 24 8b 74 24 28 8b 7c 24 2c 8b 6c 24 30 cd 80 <5b> 5e 5f 5d c3 5b 5e 5f 5d e9 f7 a1 ff ff 66 90 66 90 66 90 90 53 RSP: 002b:00000000f54052bc EFLAGS: 00000246 ORIG_RAX: 0000000000000004 RAX: ffffffffffffffda RBX: 0000000000000002 RCX: 00000000f54054bc RDX: 0000000000000027 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000292 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 ---------------- Code disassembly (best guess): 0: 57 push %rdi 1: 56 push %rsi 2: 53 push %rbx 3: 8b 44 24 14 mov 0x14(%rsp),%eax 7: f6 00 08 testb $0x8,(%rax) a: 75 23 jne 0x2f c: 8b 44 24 18 mov 0x18(%rsp),%eax 10: 8b 5c 24 1c mov 0x1c(%rsp),%ebx 14: 8b 4c 24 20 mov 0x20(%rsp),%ecx 18: 8b 54 24 24 mov 0x24(%rsp),%edx 1c: 8b 74 24 28 mov 0x28(%rsp),%esi 20: 8b 7c 24 2c mov 0x2c(%rsp),%edi 24: 8b 6c 24 30 mov 0x30(%rsp),%ebp 28: cd 80 int $0x80 * 2a: 5b pop %rbx <-- trapping instruction 2b: 5e pop %rsi 2c: 5f pop %rdi 2d: 5d pop %rbp 2e: c3 ret 2f: 5b pop %rbx 30: 5e pop %rsi 31: 5f pop %rdi 32: 5d pop %rbp 33: e9 f7 a1 ff ff jmp 0xffffa22f 38: 66 90 xchg %ax,%ax 3a: 66 90 xchg %ax,%ax 3c: 66 90 xchg %ax,%ax 3e: 90 nop 3f: 53 push %rbx