====================================================== WARNING: possible circular locking dependency detected 5.6.0-syzkaller #0 Not tainted ------------------------------------------------------ syz-executor.2/10743 is trying to acquire lock: ffff88803dcb0bf0 (&ovl_i_mutex_dir_key[depth]){++++}-{3:3}, at: inode_lock_shared include/linux/fs.h:807 [inline] ffff88803dcb0bf0 (&ovl_i_mutex_dir_key[depth]){++++}-{3:3}, at: lookup_slow fs/namei.c:1546 [inline] ffff88803dcb0bf0 (&ovl_i_mutex_dir_key[depth]){++++}-{3:3}, at: walk_component+0x435/0x680 fs/namei.c:1846 but task is already holding lock: ffff88803dbedb88 (&sig->exec_update_mutex){+.+.}-{3:3}, at: __do_sys_perf_event_open kernel/events/core.c:11554 [inline] ffff88803dbedb88 (&sig->exec_update_mutex){+.+.}-{3:3}, at: __se_sys_perf_event_open+0xc40/0x4000 kernel/events/core.c:11448 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #3 (&sig->exec_update_mutex){+.+.}-{3:3}: lock_acquire+0x169/0x480 kernel/locking/lockdep.c:4923 __mutex_lock_common+0x189/0x2fc0 kernel/locking/mutex.c:956 __mutex_lock kernel/locking/mutex.c:1103 [inline] mutex_lock_killable_nested+0x1a/0x20 kernel/locking/mutex.c:1133 do_io_accounting fs/proc/base.c:2886 [inline] proc_tgid_io_accounting+0x163/0x570 fs/proc/base.c:2935 proc_single_show+0xd5/0x160 fs/proc/base.c:758 traverse+0x20c/0x540 fs/seq_file.c:113 seq_read+0xc26/0xd20 fs/seq_file.c:188 do_loop_readv_writev fs/read_write.c:714 [inline] do_iter_read+0x44b/0x550 fs/read_write.c:935 vfs_readv+0xc2/0x120 fs/read_write.c:1053 kernel_readv fs/splice.c:365 [inline] default_file_splice_read+0x579/0xa40 fs/splice.c:422 do_splice_to fs/splice.c:892 [inline] splice_direct_to_actor+0x3c1/0xb40 fs/splice.c:971 do_splice_direct+0x201/0x340 fs/splice.c:1080 do_sendfile+0x809/0xfe0 fs/read_write.c:1520 __do_sys_sendfile64 fs/read_write.c:1575 [inline] __se_sys_sendfile64 fs/read_write.c:1567 [inline] __x64_sys_sendfile64+0xed/0x1a0 fs/read_write.c:1567 do_syscall_64+0xf3/0x1b0 arch/x86/entry/common.c:295 entry_SYSCALL_64_after_hwframe+0x49/0xb3 -> #2 (&p->lock){+.+.}-{3:3}: lock_acquire+0x169/0x480 kernel/locking/lockdep.c:4923 __mutex_lock_common+0x189/0x2fc0 kernel/locking/mutex.c:956 __mutex_lock kernel/locking/mutex.c:1103 [inline] mutex_lock_nested+0x1a/0x20 kernel/locking/mutex.c:1118 seq_read+0x66/0xd20 fs/seq_file.c:161 do_loop_readv_writev fs/read_write.c:714 [inline] do_iter_read+0x44b/0x550 fs/read_write.c:935 vfs_readv+0xc2/0x120 fs/read_write.c:1053 kernel_readv fs/splice.c:365 [inline] default_file_splice_read+0x579/0xa40 fs/splice.c:422 do_splice_to fs/splice.c:892 [inline] splice_direct_to_actor+0x3c1/0xb40 fs/splice.c:971 do_splice_direct+0x201/0x340 fs/splice.c:1080 do_sendfile+0x809/0xfe0 fs/read_write.c:1520 __do_sys_sendfile64 fs/read_write.c:1581 [inline] __se_sys_sendfile64 fs/read_write.c:1567 [inline] __x64_sys_sendfile64+0x164/0x1a0 fs/read_write.c:1567 do_syscall_64+0xf3/0x1b0 arch/x86/entry/common.c:295 entry_SYSCALL_64_after_hwframe+0x49/0xb3 -> #1 (sb_writers#3){.+.+}-{0:0}: lock_acquire+0x169/0x480 kernel/locking/lockdep.c:4923 percpu_down_read include/linux/percpu-rwsem.h:51 [inline] __sb_start_write+0x14b/0x410 fs/super.c:1674 sb_start_write include/linux/fs.h:1655 [inline] mnt_want_write+0x45/0x90 fs/namespace.c:354 ovl_create_object+0xb1/0x2b0 fs/overlayfs/dir.c:596 lookup_open fs/namei.c:3081 [inline] open_last_lookups fs/namei.c:3155 [inline] path_openat+0x17ee/0x38b0 fs/namei.c:3343 do_filp_open+0x191/0x3a0 fs/namei.c:3373 do_sys_openat2+0x463/0x770 fs/open.c:1148 do_sys_open fs/open.c:1164 [inline] ksys_open include/linux/syscalls.h:1386 [inline] __do_sys_open fs/open.c:1170 [inline] __se_sys_open fs/open.c:1168 [inline] __x64_sys_open+0x1af/0x1e0 fs/open.c:1168 do_syscall_64+0xf3/0x1b0 arch/x86/entry/common.c:295 entry_SYSCALL_64_after_hwframe+0x49/0xb3 -> #0 (&ovl_i_mutex_dir_key[depth]){++++}-{3:3}: check_prev_add kernel/locking/lockdep.c:2515 [inline] check_prevs_add kernel/locking/lockdep.c:2620 [inline] validate_chain+0x1b09/0x8920 kernel/locking/lockdep.c:3237 __lock_acquire+0x116c/0x2b90 kernel/locking/lockdep.c:4344 lock_acquire+0x169/0x480 kernel/locking/lockdep.c:4923 down_read+0x36/0x50 kernel/locking/rwsem.c:1492 inode_lock_shared include/linux/fs.h:807 [inline] lookup_slow fs/namei.c:1546 [inline] walk_component+0x435/0x680 fs/namei.c:1846 lookup_last fs/namei.c:2295 [inline] path_lookupat+0x19d/0x960 fs/namei.c:2319 filename_lookup+0x1ab/0x5d0 fs/namei.c:2352 create_local_trace_uprobe+0x3f/0x5f0 kernel/trace/trace_uprobe.c:1575 perf_uprobe_init+0xfe/0x1a0 kernel/trace/trace_event_perf.c:323 perf_uprobe_event_init+0xd9/0x170 kernel/events/core.c:9450 perf_try_init_event+0x13e/0x3a0 kernel/events/core.c:10751 perf_init_event kernel/events/core.c:10803 [inline] perf_event_alloc+0xe13/0x2d60 kernel/events/core.c:11079 __do_sys_perf_event_open kernel/events/core.c:11574 [inline] __se_sys_perf_event_open+0x685/0x4000 kernel/events/core.c:11448 do_syscall_64+0xf3/0x1b0 arch/x86/entry/common.c:295 entry_SYSCALL_64_after_hwframe+0x49/0xb3 other info that might help us debug this: Chain exists of: &ovl_i_mutex_dir_key[depth] --> &p->lock --> &sig->exec_update_mutex Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&sig->exec_update_mutex); lock(&p->lock); lock(&sig->exec_update_mutex); lock(&ovl_i_mutex_dir_key[depth]); *** DEADLOCK *** 2 locks held by syz-executor.2/10743: #0: ffff88803dbedb88 (&sig->exec_update_mutex){+.+.}-{3:3}, at: __do_sys_perf_event_open kernel/events/core.c:11554 [inline] #0: ffff88803dbedb88 (&sig->exec_update_mutex){+.+.}-{3:3}, at: __se_sys_perf_event_open+0xc40/0x4000 kernel/events/core.c:11448 #1: ffffffff8b599080 (&pmus_srcu){....}-{0:0}, at: rcu_lock_acquire+0x9/0x30 include/linux/rcupdate.h:208 stack backtrace: CPU: 1 PID: 10743 Comm: syz-executor.2 Not tainted 5.6.0-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+0x1e9/0x30e lib/dump_stack.c:118 print_circular_bug+0xc72/0xea0 kernel/locking/lockdep.c:1722 check_noncircular+0x1fb/0x3a0 kernel/locking/lockdep.c:1846 check_prev_add kernel/locking/lockdep.c:2515 [inline] check_prevs_add kernel/locking/lockdep.c:2620 [inline] validate_chain+0x1b09/0x8920 kernel/locking/lockdep.c:3237 __lock_acquire+0x116c/0x2b90 kernel/locking/lockdep.c:4344 lock_acquire+0x169/0x480 kernel/locking/lockdep.c:4923 down_read+0x36/0x50 kernel/locking/rwsem.c:1492 inode_lock_shared include/linux/fs.h:807 [inline] lookup_slow fs/namei.c:1546 [inline] walk_component+0x435/0x680 fs/namei.c:1846 lookup_last fs/namei.c:2295 [inline] path_lookupat+0x19d/0x960 fs/namei.c:2319 filename_lookup+0x1ab/0x5d0 fs/namei.c:2352 create_local_trace_uprobe+0x3f/0x5f0 kernel/trace/trace_uprobe.c:1575 perf_uprobe_init+0xfe/0x1a0 kernel/trace/trace_event_perf.c:323 perf_uprobe_event_init+0xd9/0x170 kernel/events/core.c:9450 perf_try_init_event+0x13e/0x3a0 kernel/events/core.c:10751 perf_init_event kernel/events/core.c:10803 [inline] perf_event_alloc+0xe13/0x2d60 kernel/events/core.c:11079 __do_sys_perf_event_open kernel/events/core.c:11574 [inline] __se_sys_perf_event_open+0x685/0x4000 kernel/events/core.c:11448 do_syscall_64+0xf3/0x1b0 arch/x86/entry/common.c:295 entry_SYSCALL_64_after_hwframe+0x49/0xb3 RIP: 0033:0x45c879 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:00007fe8794d2c78 EFLAGS: 00000246 ORIG_RAX: 000000000000012a RAX: ffffffffffffffda RBX: 00007fe8794d36d4 RCX: 000000000045c879 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000020000180 RBP: 000000000076bf00 R08: 0000000000000000 R09: 0000000000000000 R10: ffffffffffffffff R11: 0000000000000246 R12: 00000000ffffffff R13: 0000000000000816 R14: 00000000004cad01 R15: 000000000076bf0c