====================================================== WARNING: possible circular locking dependency detected 5.5.0-rc2-syzkaller #0 Not tainted ------------------------------------------------------ syz-executor.0/22524 is trying to acquire lock: ffff888096faf690 (&ovl_i_mutex_dir_key[depth]#2){.+.+}, at: inode_lock_shared include/linux/fs.h:801 [inline] ffff888096faf690 (&ovl_i_mutex_dir_key[depth]#2){.+.+}, at: lookup_slow+0x4a/0x80 fs/namei.c:1681 but task is already holding lock: ffff88809e01d690 (&sig->cred_guard_mutex){+.+.}, at: __do_sys_perf_event_open+0xeaa/0x2c70 kernel/events/core.c:11257 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:956 [inline] __mutex_lock+0x156/0x13c0 kernel/locking/mutex.c:1103 mutex_lock_killable_nested+0x16/0x20 kernel/locking/mutex.c:1133 lock_trace+0x4a/0xe0 fs/proc/base.c:406 proc_pid_syscall+0x8a/0x220 fs/proc/base.c:635 proc_single_show+0xfd/0x1c0 fs/proc/base.c:756 traverse fs/seq_file.c:113 [inline] traverse+0x1cd/0x730 fs/seq_file.c:91 seq_lseek+0x168/0x3e0 fs/seq_file.c:326 vfs_llseek fs/read_write.c:300 [inline] ksys_lseek+0x116/0x1b0 fs/read_write.c:313 __do_sys_lseek fs/read_write.c:324 [inline] __se_sys_lseek fs/read_write.c:322 [inline] __x64_sys_lseek+0x73/0xb0 fs/read_write.c:322 do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #3 (&p->lock){+.+.}: __mutex_lock_common kernel/locking/mutex.c:956 [inline] __mutex_lock+0x156/0x13c0 kernel/locking/mutex.c:1103 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1118 seq_read+0x71/0x1170 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+0x4a4/0x660 fs/read_write.c:935 vfs_readv+0xf0/0x160 fs/read_write.c:997 kernel_readv fs/splice.c:365 [inline] default_file_splice_read+0x4fb/0xa20 fs/splice.c:422 do_splice_to+0x127/0x180 fs/splice.c:892 splice_direct_to_actor+0x320/0xa30 fs/splice.c:971 do_splice_direct+0x1da/0x2a0 fs/splice.c:1080 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+0xfa/0x790 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #2 (sb_writers#3){.+.+}: percpu_down_read include/linux/percpu-rwsem.h:40 [inline] __sb_start_write+0x241/0x460 fs/super.c:1672 sb_start_write include/linux/fs.h:1650 [inline] mnt_want_write+0x3f/0xc0 fs/namespace.c:354 ovl_want_write+0x76/0xa0 fs/overlayfs/util.c:21 ovl_create_object+0xb3/0x2c0 fs/overlayfs/dir.c:596 ovl_create+0x28/0x30 fs/overlayfs/dir.c:627 lookup_open+0x12d5/0x1a90 fs/namei.c:3241 do_last fs/namei.c:3331 [inline] path_openat+0x14a2/0x4500 fs/namei.c:3537 do_filp_open+0x1a1/0x280 fs/namei.c:3567 do_sys_open+0x3fe/0x5d0 fs/open.c:1097 ksys_open include/linux/syscalls.h:1382 [inline] __do_sys_creat fs/open.c:1155 [inline] __se_sys_creat fs/open.c:1153 [inline] __x64_sys_creat+0x61/0x80 fs/open.c:1153 do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #1 (&ovl_i_mutex_dir_key[depth]){++++}: down_read+0x95/0x430 kernel/locking/rwsem.c:1495 inode_lock_shared include/linux/fs.h:801 [inline] lookup_slow+0x4a/0x80 fs/namei.c:1681 lookup_one_len_unlocked+0xf6/0x100 fs/namei.c:2559 lookup_positive_unlocked+0x27/0xc0 fs/namei.c:2575 ovl_lookup_single+0x63/0x900 fs/overlayfs/namei.c:203 ovl_lookup_layer+0x40d/0x4c0 fs/overlayfs/namei.c:287 ovl_lookup+0xce2/0x1a10 fs/overlayfs/namei.c:902 __lookup_slow+0x279/0x500 fs/namei.c:1665 lookup_slow+0x58/0x80 fs/namei.c:1682 walk_component+0x747/0x1df0 fs/namei.c:1802 link_path_walk.part.0+0x9a4/0x1340 fs/namei.c:2128 link_path_walk fs/namei.c:2059 [inline] path_parentat.isra.0+0x51/0x160 fs/namei.c:2353 filename_parentat.isra.0+0x19c/0x410 fs/namei.c:2375 filename_create+0xb3/0x4f0 fs/namei.c:3621 user_path_create fs/namei.c:3696 [inline] do_mkdirat+0xb5/0x2a0 fs/namei.c:3834 __do_sys_mkdir fs/namei.c:3858 [inline] __se_sys_mkdir fs/namei.c:3856 [inline] __x64_sys_mkdir+0x5c/0x80 fs/namei.c:3856 do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #0 (&ovl_i_mutex_dir_key[depth]#2){.+.+}: check_prev_add kernel/locking/lockdep.c:2476 [inline] check_prevs_add kernel/locking/lockdep.c:2581 [inline] validate_chain kernel/locking/lockdep.c:2971 [inline] __lock_acquire+0x2596/0x4a00 kernel/locking/lockdep.c:3955 lock_acquire+0x190/0x410 kernel/locking/lockdep.c:4485 down_read+0x95/0x430 kernel/locking/rwsem.c:1495 inode_lock_shared include/linux/fs.h:801 [inline] lookup_slow+0x4a/0x80 fs/namei.c:1681 walk_component+0x747/0x1df0 fs/namei.c:1802 lookup_last fs/namei.c:2260 [inline] path_lookupat.isra.0+0x1f5/0x8d0 fs/namei.c:2305 filename_lookup+0x1b0/0x3f0 fs/namei.c:2335 kern_path+0x36/0x40 fs/namei.c:2421 create_local_trace_uprobe+0x87/0x4a0 kernel/trace/trace_uprobe.c:1542 perf_uprobe_init+0x131/0x210 kernel/trace/trace_event_perf.c:323 perf_uprobe_event_init+0x106/0x1a0 kernel/events/core.c:9162 perf_try_init_event+0x135/0x590 kernel/events/core.c:10462 perf_init_event kernel/events/core.c:10514 [inline] perf_event_alloc.part.0+0x158f/0x3710 kernel/events/core.c:10794 perf_event_alloc kernel/events/core.c:10676 [inline] __do_sys_perf_event_open+0x6f8/0x2c70 kernel/events/core.c:11277 __se_sys_perf_event_open kernel/events/core.c:11151 [inline] __x64_sys_perf_event_open+0xbe/0x150 kernel/events/core.c:11151 do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe other info that might help us debug this: Chain exists of: &ovl_i_mutex_dir_key[depth]#2 --> &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]#2); *** DEADLOCK *** 2 locks held by syz-executor.0/22524: #0: ffff88809e01d690 (&sig->cred_guard_mutex){+.+.}, at: __do_sys_perf_event_open+0xeaa/0x2c70 kernel/events/core.c:11257 #1: ffffffff8b6480a8 (&pmus_srcu){....}, at: perf_event_alloc.part.0+0xefc/0x3710 kernel/events/core.c:10790 stack backtrace: CPU: 0 PID: 22524 Comm: syz-executor.0 Not tainted 5.5.0-rc2-syzkaller #0 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+0x197/0x210 lib/dump_stack.c:118 print_circular_bug.isra.0.cold+0x163/0x172 kernel/locking/lockdep.c:1685 check_noncircular+0x32e/0x3e0 kernel/locking/lockdep.c:1809 check_prev_add kernel/locking/lockdep.c:2476 [inline] check_prevs_add kernel/locking/lockdep.c:2581 [inline] validate_chain kernel/locking/lockdep.c:2971 [inline] __lock_acquire+0x2596/0x4a00 kernel/locking/lockdep.c:3955 lock_acquire+0x190/0x410 kernel/locking/lockdep.c:4485 down_read+0x95/0x430 kernel/locking/rwsem.c:1495 inode_lock_shared include/linux/fs.h:801 [inline] lookup_slow+0x4a/0x80 fs/namei.c:1681 walk_component+0x747/0x1df0 fs/namei.c:1802 lookup_last fs/namei.c:2260 [inline] path_lookupat.isra.0+0x1f5/0x8d0 fs/namei.c:2305 filename_lookup+0x1b0/0x3f0 fs/namei.c:2335 kern_path+0x36/0x40 fs/namei.c:2421 create_local_trace_uprobe+0x87/0x4a0 kernel/trace/trace_uprobe.c:1542 perf_uprobe_init+0x131/0x210 kernel/trace/trace_event_perf.c:323 perf_uprobe_event_init+0x106/0x1a0 kernel/events/core.c:9162 perf_try_init_event+0x135/0x590 kernel/events/core.c:10462 perf_init_event kernel/events/core.c:10514 [inline] perf_event_alloc.part.0+0x158f/0x3710 kernel/events/core.c:10794 perf_event_alloc kernel/events/core.c:10676 [inline] __do_sys_perf_event_open+0x6f8/0x2c70 kernel/events/core.c:11277 __se_sys_perf_event_open kernel/events/core.c:11151 [inline] __x64_sys_perf_event_open+0xbe/0x150 kernel/events/core.c:11151 do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x45a919 Code: ad b6 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 b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007f3064354c78 EFLAGS: 00000246 ORIG_RAX: 000000000000012a RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 000000000045a919 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000020000180 RBP: 000000000075bfc8 R08: 0000000000000000 R09: 0000000000000000 R10: ffffffffffffffff R11: 0000000000000246 R12: 00007f30643556d4 R13: 00000000004c87fb R14: 00000000004dfdf8 R15: 00000000ffffffff