====================================================== WARNING: possible circular locking dependency detected 5.1.0-next-20190517 #16 Not tainted ------------------------------------------------------ syz-executor.5/14735 is trying to acquire lock: 000000000938af8f (&sig->cred_guard_mutex){+.+.}, at: lock_trace+0x4a/0xe0 fs/proc/base.c:388 but task is already holding lock: 00000000a9518883 (&p->lock){+.+.}, at: seq_read+0x71/0x1130 fs/seq_file.c:161 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #3 (&p->lock){+.+.}: __mutex_lock_common kernel/locking/mutex.c:925 [inline] __mutex_lock+0xf7/0x1310 kernel/locking/mutex.c:1072 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1087 seq_read+0x71/0x1130 fs/seq_file.c:161 do_loop_readv_writev fs/read_write.c:714 [inline] do_loop_readv_writev fs/read_write.c:701 [inline] do_iter_read+0x4a9/0x660 fs/read_write.c:935 vfs_readv+0xf0/0x160 fs/read_write.c:997 kernel_readv fs/splice.c:358 [inline] default_file_splice_read+0x475/0x890 fs/splice.c:413 do_splice_to+0x12a/0x190 fs/splice.c:876 splice_direct_to_actor+0x2d2/0x970 fs/splice.c:953 do_splice_direct+0x1da/0x2a0 fs/splice.c:1062 do_sendfile+0x597/0xd00 fs/read_write.c:1464 __do_sys_sendfile64 fs/read_write.c:1525 [inline] __se_sys_sendfile64 fs/read_write.c:1511 [inline] __x64_sys_sendfile64+0x1dd/0x220 fs/read_write.c:1511 do_syscall_64+0x103/0x680 arch/x86/entry/common.c:301 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #2 (sb_writers#3){.+.+}: percpu_down_read include/linux/percpu-rwsem.h:36 [inline] __sb_start_write+0x20b/0x360 fs/super.c:1608 sb_start_write include/linux/fs.h:1627 [inline] mnt_want_write+0x3f/0xc0 fs/namespace.c:359 ovl_want_write+0x76/0xa0 fs/overlayfs/util.c:24 ovl_xattr_set+0x53/0x5b0 fs/overlayfs/inode.c:332 ovl_other_xattr_set+0x39/0x50 fs/overlayfs/super.c:945 __vfs_removexattr+0x112/0x180 fs/xattr.c:376 vfs_removexattr+0xb7/0x200 fs/xattr.c:395 removexattr+0xda/0x130 fs/xattr.c:690 path_removexattr+0x166/0x180 fs/xattr.c:704 __do_sys_lremovexattr fs/xattr.c:724 [inline] __se_sys_lremovexattr fs/xattr.c:721 [inline] __x64_sys_lremovexattr+0x56/0x80 fs/xattr.c:721 do_syscall_64+0x103/0x680 arch/x86/entry/common.c:301 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #1 (&ovl_i_mutex_dir_key[depth]){++++}: down_read+0x3f/0x1e0 kernel/locking/rwsem.c:24 inode_lock_shared include/linux/fs.h:788 [inline] lookup_slow+0x4a/0x80 fs/namei.c:1685 walk_component+0x74b/0x2000 fs/namei.c:1808 lookup_last fs/namei.c:2271 [inline] path_lookupat.isra.0+0x1f5/0x8d0 fs/namei.c:2316 filename_lookup+0x1b0/0x410 fs/namei.c:2346 kern_path+0x36/0x40 fs/namei.c:2432 create_local_trace_uprobe+0x87/0x4e0 kernel/trace/trace_uprobe.c:1389 perf_uprobe_init+0x131/0x210 kernel/trace/trace_event_perf.c:314 perf_uprobe_event_init+0x106/0x1a0 kernel/events/core.c:8787 perf_try_init_event+0x137/0x3f0 kernel/events/core.c:10061 perf_init_event kernel/events/core.c:10101 [inline] perf_event_alloc.part.0+0x1f62/0x3230 kernel/events/core.c:10379 perf_event_alloc kernel/events/core.c:10749 [inline] __do_sys_perf_event_open+0x830/0x24e0 kernel/events/core.c:10850 __se_sys_perf_event_open kernel/events/core.c:10739 [inline] __x64_sys_perf_event_open+0xbe/0x150 kernel/events/core.c:10739 do_syscall_64+0x103/0x680 arch/x86/entry/common.c:301 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #0 (&sig->cred_guard_mutex){+.+.}: lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:4302 __mutex_lock_common kernel/locking/mutex.c:925 [inline] __mutex_lock+0xf7/0x1310 kernel/locking/mutex.c:1072 mutex_lock_killable_nested+0x16/0x20 kernel/locking/mutex.c:1102 lock_trace+0x4a/0xe0 fs/proc/base.c:388 proc_pid_personality+0x1c/0xd0 fs/proc/base.c:2928 proc_single_show+0xf6/0x170 fs/proc/base.c:739 seq_read+0x4db/0x1130 fs/seq_file.c:229 __vfs_read+0x8d/0x110 fs/read_write.c:425 vfs_read+0x194/0x3e0 fs/read_write.c:461 ksys_read+0x14f/0x290 fs/read_write.c:587 __do_sys_read fs/read_write.c:597 [inline] __se_sys_read fs/read_write.c:595 [inline] __x64_sys_read+0x73/0xb0 fs/read_write.c:595 do_syscall_64+0x103/0x680 arch/x86/entry/common.c:301 entry_SYSCALL_64_after_hwframe+0x49/0xbe other info that might help us debug this: Chain exists of: &sig->cred_guard_mutex --> sb_writers#3 --> &p->lock Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&p->lock); lock(sb_writers#3); lock(&p->lock); lock(&sig->cred_guard_mutex); *** DEADLOCK *** 2 locks held by syz-executor.5/14735: #0: 000000003e497ee7 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0xee/0x110 fs/file.c:801 #1: 00000000a9518883 (&p->lock){+.+.}, at: seq_read+0x71/0x1130 fs/seq_file.c:161 stack backtrace: CPU: 1 PID: 14735 Comm: syz-executor.5 Not tainted 5.1.0-next-20190517 #16 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x172/0x1f0 lib/dump_stack.c:113 print_circular_bug.cold+0x1cc/0x28f kernel/locking/lockdep.c:1564 check_prev_add kernel/locking/lockdep.c:2309 [inline] check_prevs_add kernel/locking/lockdep.c:2417 [inline] validate_chain kernel/locking/lockdep.c:2799 [inline] __lock_acquire+0x3755/0x5490 kernel/locking/lockdep.c:3792 lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:4302 __mutex_lock_common kernel/locking/mutex.c:925 [inline] __mutex_lock+0xf7/0x1310 kernel/locking/mutex.c:1072 mutex_lock_killable_nested+0x16/0x20 kernel/locking/mutex.c:1102 lock_trace+0x4a/0xe0 fs/proc/base.c:388 proc_pid_personality+0x1c/0xd0 fs/proc/base.c:2928 proc_single_show+0xf6/0x170 fs/proc/base.c:739 seq_read+0x4db/0x1130 fs/seq_file.c:229 __vfs_read+0x8d/0x110 fs/read_write.c:425 vfs_read+0x194/0x3e0 fs/read_write.c:461 ksys_read+0x14f/0x290 fs/read_write.c:587 __do_sys_read fs/read_write.c:597 [inline] __se_sys_read fs/read_write.c:595 [inline] __x64_sys_read+0x73/0xb0 fs/read_write.c:595 do_syscall_64+0x103/0x680 arch/x86/entry/common.c:301 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x458da9 Code: ad b8 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 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 0f 83 7b b8 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007f8737bf3c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000000 RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000458da9 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000003 RBP: 000000000073bf00 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f8737bf46d4 R13: 00000000004c5d22 R14: 00000000004da4b8 R15: 00000000ffffffff