====================================================== WARNING: possible circular locking dependency detected 4.19.211-syzkaller #0 Not tainted ------------------------------------------------------ syz-executor.0/773 is trying to acquire lock: 0000000076c38889 (&ovl_i_mutex_dir_key[depth]#2){++++}, at: inode_lock_shared include/linux/fs.h:758 [inline] 0000000076c38889 (&ovl_i_mutex_dir_key[depth]#2){++++}, at: lookup_slow fs/namei.c:1688 [inline] 0000000076c38889 (&ovl_i_mutex_dir_key[depth]#2){++++}, at: walk_component+0x798/0xda0 fs/namei.c:1811 but task is already holding lock: 0000000019f638cd (&sig->cred_guard_mutex){+.+.}, at: __do_sys_perf_event_open kernel/events/core.c:10640 [inline] 0000000019f638cd (&sig->cred_guard_mutex){+.+.}, at: __se_sys_perf_event_open+0x18eb/0x2720 kernel/events/core.c:10549 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #3 (&sig->cred_guard_mutex){+.+.}: lock_trace fs/proc/base.c:402 [inline] proc_pid_stack+0x160/0x350 fs/proc/base.c:452 proc_single_show+0xeb/0x170 fs/proc/base.c:755 seq_read+0x4e0/0x11c0 fs/seq_file.c:232 do_loop_readv_writev fs/read_write.c:701 [inline] do_loop_readv_writev fs/read_write.c:688 [inline] do_iter_read+0x471/0x630 fs/read_write.c:925 vfs_readv+0xe5/0x150 fs/read_write.c:987 do_preadv fs/read_write.c:1071 [inline] __do_sys_preadv fs/read_write.c:1121 [inline] __se_sys_preadv fs/read_write.c:1116 [inline] __x64_sys_preadv+0x22b/0x310 fs/read_write.c:1116 do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #2 (&p->lock){+.+.}: seq_read+0x6b/0x11c0 fs/seq_file.c:164 proc_reg_read+0x1bd/0x2d0 fs/proc/inode.c:231 do_loop_readv_writev fs/read_write.c:701 [inline] do_loop_readv_writev fs/read_write.c:688 [inline] do_iter_read+0x471/0x630 fs/read_write.c:925 vfs_readv+0xe5/0x150 fs/read_write.c:987 kernel_readv fs/splice.c:362 [inline] default_file_splice_read+0x457/0xa00 fs/splice.c:417 do_splice_to+0x10e/0x160 fs/splice.c:881 splice_direct_to_actor+0x2b9/0x8d0 fs/splice.c:959 do_splice_direct+0x1a7/0x270 fs/splice.c:1068 do_sendfile+0x550/0xc30 fs/read_write.c:1447 __do_sys_sendfile64 fs/read_write.c:1508 [inline] __se_sys_sendfile64+0x147/0x160 fs/read_write.c:1494 do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #1 (sb_writers#3){.+.+}: sb_start_write include/linux/fs.h:1579 [inline] mnt_want_write+0x3a/0xb0 fs/namespace.c:360 ovl_create_object+0x96/0x290 fs/overlayfs/dir.c:602 lookup_open+0x893/0x1a20 fs/namei.c:3235 do_last fs/namei.c:3327 [inline] path_openat+0x1094/0x2df0 fs/namei.c:3537 do_filp_open+0x18c/0x3f0 fs/namei.c:3567 do_sys_open+0x3b3/0x520 fs/open.c:1085 do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #0 (&ovl_i_mutex_dir_key[depth]#2){++++}: down_read+0x36/0x80 kernel/locking/rwsem.c:24 inode_lock_shared include/linux/fs.h:758 [inline] lookup_slow fs/namei.c:1688 [inline] walk_component+0x798/0xda0 fs/namei.c:1811 lookup_last fs/namei.c:2274 [inline] path_lookupat+0x1ff/0x8d0 fs/namei.c:2319 filename_lookup+0x1ac/0x5a0 fs/namei.c:2349 create_local_trace_uprobe+0x82/0x490 kernel/trace/trace_uprobe.c:1356 perf_uprobe_init+0x128/0x200 kernel/trace/trace_event_perf.c:317 perf_uprobe_event_init+0xf8/0x190 kernel/events/core.c:8613 perf_try_init_event+0x124/0x2e0 kernel/events/core.c:9884 perf_init_event kernel/events/core.c:9915 [inline] perf_event_alloc.part.0+0x1b16/0x2eb0 kernel/events/core.c:10189 perf_event_alloc kernel/events/core.c:10559 [inline] __do_sys_perf_event_open kernel/events/core.c:10660 [inline] __se_sys_perf_event_open+0x550/0x2720 kernel/events/core.c:10549 do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293 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.0/773: #0: 0000000019f638cd (&sig->cred_guard_mutex){+.+.}, at: __do_sys_perf_event_open kernel/events/core.c:10640 [inline] #0: 0000000019f638cd (&sig->cred_guard_mutex){+.+.}, at: __se_sys_perf_event_open+0x18eb/0x2720 kernel/events/core.c:10549 #1: 00000000df28bae6 (&pmus_srcu){....}, at: perf_event_alloc.part.0+0xe6c/0x2eb0 kernel/events/core.c:10185 stack backtrace: CPU: 0 PID: 773 Comm: syz-executor.0 Not tainted 4.19.211-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+0x1fc/0x2ef lib/dump_stack.c:118 print_circular_bug.constprop.0.cold+0x2d7/0x41e kernel/locking/lockdep.c:1222 check_prev_add kernel/locking/lockdep.c:1866 [inline] check_prevs_add kernel/locking/lockdep.c:1979 [inline] validate_chain kernel/locking/lockdep.c:2420 [inline] __lock_acquire+0x30c9/0x3ff0 kernel/locking/lockdep.c:3416 lock_acquire+0x170/0x3c0 kernel/locking/lockdep.c:3908 down_read+0x36/0x80 kernel/locking/rwsem.c:24 inode_lock_shared include/linux/fs.h:758 [inline] lookup_slow fs/namei.c:1688 [inline] walk_component+0x798/0xda0 fs/namei.c:1811 lookup_last fs/namei.c:2274 [inline] path_lookupat+0x1ff/0x8d0 fs/namei.c:2319 filename_lookup+0x1ac/0x5a0 fs/namei.c:2349 create_local_trace_uprobe+0x82/0x490 kernel/trace/trace_uprobe.c:1356 perf_uprobe_init+0x128/0x200 kernel/trace/trace_event_perf.c:317 perf_uprobe_event_init+0xf8/0x190 kernel/events/core.c:8613 perf_try_init_event+0x124/0x2e0 kernel/events/core.c:9884 perf_init_event kernel/events/core.c:9915 [inline] perf_event_alloc.part.0+0x1b16/0x2eb0 kernel/events/core.c:10189 perf_event_alloc kernel/events/core.c:10559 [inline] __do_sys_perf_event_open kernel/events/core.c:10660 [inline] __se_sys_perf_event_open+0x550/0x2720 kernel/events/core.c:10549 do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x7fb80572d109 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 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 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fb804081168 EFLAGS: 00000246 ORIG_RAX: 000000000000012a RAX: ffffffffffffffda RBX: 00007fb805840030 RCX: 00007fb80572d109 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000020000080 RBP: 00007fb8057870ad R08: 0000000000000000 R09: 0000000000000000 R10: ffffffffffffffff R11: 0000000000000246 R12: 0000000000000000 R13: 00007fff5f9b03ff R14: 00007fb804081300 R15: 0000000000022000