====================================================== WARNING: possible circular locking dependency detected 5.2.0-rc1+ #7 Not tainted ------------------------------------------------------ syz-executor.5/12070 is trying to acquire lock: 000000006b65e581 (&ovl_i_mutex_dir_key[depth]){++++}, at: inode_lock_shared include/linux/fs.h:788 [inline] 000000006b65e581 (&ovl_i_mutex_dir_key[depth]){++++}, at: lookup_slow+0x4a/0x80 fs/namei.c:1685 but task is already holding lock: 0000000048b0e5e0 (&sig->cred_guard_mutex){+.+.}, at: __do_sys_perf_event_open+0x6d2/0x24d0 kernel/events/core.c:10830 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #4 (&sig->cred_guard_mutex){+.+.}: __mutex_lock_common kernel/locking/mutex.c:926 [inline] __mutex_lock+0xf7/0x1310 kernel/locking/mutex.c:1073 mutex_lock_killable_nested+0x16/0x20 kernel/locking/mutex.c:1103 lock_trace+0x4a/0xe0 fs/proc/base.c:388 proc_pid_stack+0xbf/0x200 fs/proc/base.c:432 proc_single_show+0xf0/0x170 fs/proc/base.c:739 seq_read+0x4ca/0x1110 fs/seq_file.c:229 do_loop_readv_writev fs/read_write.c:714 [inline] do_loop_readv_writev fs/read_write.c:701 [inline] do_iter_read+0x4a4/0x660 fs/read_write.c:935 vfs_readv+0xf0/0x160 fs/read_write.c:997 kernel_readv fs/splice.c:359 [inline] default_file_splice_read+0x475/0x890 fs/splice.c:414 do_splice_to+0x127/0x180 fs/splice.c:877 splice_direct_to_actor+0x2d2/0x970 fs/splice.c:954 do_splice_direct+0x1da/0x2a0 fs/splice.c:1063 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+0xfd/0x680 arch/x86/entry/common.c:301 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #3 (&p->lock){+.+.}: __mutex_lock_common kernel/locking/mutex.c:926 [inline] __mutex_lock+0xf7/0x1310 kernel/locking/mutex.c:1073 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1088 seq_read+0x71/0x1110 fs/seq_file.c:161 proc_reg_read+0x1fc/0x2c0 fs/proc/inode.c:221 do_loop_readv_writev fs/read_write.c:714 [inline] do_loop_readv_writev fs/read_write.c:701 [inline] do_iter_read+0x4a4/0x660 fs/read_write.c:935 vfs_readv+0xf0/0x160 fs/read_write.c:997 kernel_readv fs/splice.c:359 [inline] default_file_splice_read+0x475/0x890 fs/splice.c:414 do_splice_to+0x127/0x180 fs/splice.c:877 do_splice+0x1103/0x1410 fs/splice.c:1184 __do_sys_splice fs/splice.c:1425 [inline] __se_sys_splice fs/splice.c:1405 [inline] __x64_sys_splice+0x2c6/0x330 fs/splice.c:1405 do_syscall_64+0xfd/0x680 arch/x86/entry/common.c:301 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #2 (&pipe->mutex/1){+.+.}: __mutex_lock_common kernel/locking/mutex.c:926 [inline] __mutex_lock+0xf7/0x1310 kernel/locking/mutex.c:1073 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1088 pipe_lock_nested fs/pipe.c:62 [inline] pipe_lock+0x6e/0x80 fs/pipe.c:70 iter_file_splice_write+0x18b/0xbd0 fs/splice.c:697 do_splice_from fs/splice.c:848 [inline] do_splice+0x708/0x1410 fs/splice.c:1155 __do_sys_splice fs/splice.c:1425 [inline] __se_sys_splice fs/splice.c:1405 [inline] __x64_sys_splice+0x2c6/0x330 fs/splice.c:1405 do_syscall_64+0xfd/0x680 arch/x86/entry/common.c:301 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #1 (sb_writers#4){.+.+}: 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_create_object+0xb3/0x2c0 fs/overlayfs/dir.c:599 ovl_create+0x28/0x30 fs/overlayfs/dir.c:630 lookup_open+0x12d5/0x1a90 fs/namei.c:3232 do_last fs/namei.c:3322 [inline] path_openat+0x14ac/0x46d0 fs/namei.c:3533 do_filp_open+0x1a1/0x280 fs/namei.c:3563 do_sys_open+0x3fe/0x5d0 fs/open.c:1070 ksys_open include/linux/syscalls.h:1382 [inline] __do_sys_creat fs/open.c:1128 [inline] __se_sys_creat fs/open.c:1126 [inline] __x64_sys_creat+0x61/0x80 fs/open.c:1126 do_syscall_64+0xfd/0x680 arch/x86/entry/common.c:301 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #0 (&ovl_i_mutex_dir_key[depth]){++++}: lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:4303 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+0x747/0x2000 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+0x131/0x3e0 kernel/events/core.c:10061 perf_init_event kernel/events/core.c:10101 [inline] perf_event_alloc.part.0+0x1f5f/0x3220 kernel/events/core.c:10379 perf_event_alloc kernel/events/core.c:10749 [inline] __do_sys_perf_event_open+0x830/0x24d0 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+0xfd/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: &ovl_i_mutex_dir_key[depth] --> &p->lock --> &sig->cred_guard_mutex Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&sig->cred_guard_mutex); lock(&p->lock); lock(&sig->cred_guard_mutex); lock(&ovl_i_mutex_dir_key[depth]); *** DEADLOCK *** 2 locks held by syz-executor.5/12070: #0: 0000000048b0e5e0 (&sig->cred_guard_mutex){+.+.}, at: __do_sys_perf_event_open+0x6d2/0x24d0 kernel/events/core.c:10830 #1: 00000000139afb1e (&pmus_srcu){....}, at: perf_event_alloc.part.0+0xd8a/0x3220 kernel/events/core.c:10375 stack backtrace: CPU: 0 PID: 12070 Comm: syz-executor.5 Not tainted 5.2.0-rc1+ #7 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:1565 check_prev_add kernel/locking/lockdep.c:2310 [inline] check_prevs_add kernel/locking/lockdep.c:2418 [inline] validate_chain kernel/locking/lockdep.c:2800 [inline] __lock_acquire+0x3755/0x5490 kernel/locking/lockdep.c:3793 lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:4303 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+0x747/0x2000 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+0x131/0x3e0 kernel/events/core.c:10061 perf_init_event kernel/events/core.c:10101 [inline] perf_event_alloc.part.0+0x1f5f/0x3220 kernel/events/core.c:10379 perf_event_alloc kernel/events/core.c:10749 [inline] __do_sys_perf_event_open+0x830/0x24d0 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+0xfd/0x680 arch/x86/entry/common.c:301 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x459279 Code: fd b7 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 cb b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007f60cca00c78 EFLAGS: 00000246 ORIG_RAX: 000000000000012a RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 0000000000459279 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000020000180 RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000 R10: ffffffffffffffff R11: 0000000000000246 R12: 00007f60cca016d4 R13: 00000000004c5c98 R14: 00000000004da338 R15: 00000000ffffffff