====================================================== WARNING: possible circular locking dependency detected 5.9.0-rc3-syzkaller #0 Not tainted ------------------------------------------------------ syz-executor.1/5833 is trying to acquire lock: ffff88808d3806b0 (&ovl_i_mutex_dir_key[depth]){++++}-{3:3}, at: inode_lock_shared include/linux/fs.h:789 [inline] ffff88808d3806b0 (&ovl_i_mutex_dir_key[depth]){++++}-{3:3}, at: lookup_slow fs/namei.c:1560 [inline] ffff88808d3806b0 (&ovl_i_mutex_dir_key[depth]){++++}-{3:3}, at: walk_component+0x435/0x680 fs/namei.c:1860 but task is already holding lock: ffff8880a65c6c88 (&sig->exec_update_mutex){+.+.}-{3:3}, at: __do_sys_perf_event_open kernel/events/core.c:11704 [inline] ffff8880a65c6c88 (&sig->exec_update_mutex){+.+.}-{3:3}, at: __se_sys_perf_event_open+0xc8b/0x3f60 kernel/events/core.c:11598 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+0x140/0x6f0 kernel/locking/lockdep.c:5006 __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 lock_trace fs/proc/base.c:408 [inline] proc_pid_stack+0xd8/0x200 fs/proc/base.c:452 proc_single_show+0xf6/0x180 fs/proc/base.c:775 seq_read+0x41a/0xce0 fs/seq_file.c:208 do_loop_readv_writev fs/read_write.c:734 [inline] do_iter_read+0x438/0x620 fs/read_write.c:955 vfs_readv fs/read_write.c:1073 [inline] do_preadv+0x17b/0x290 fs/read_write.c:1165 do_syscall_64+0x31/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xa9 -> #2 (&p->lock){+.+.}-{3:3}: lock_acquire+0x140/0x6f0 kernel/locking/lockdep.c:5006 __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+0x60/0xce0 fs/seq_file.c:155 do_loop_readv_writev fs/read_write.c:734 [inline] do_iter_read+0x438/0x620 fs/read_write.c:955 vfs_readv+0xc2/0x120 fs/read_write.c:1073 kernel_readv fs/splice.c:355 [inline] default_file_splice_read+0x579/0xa40 fs/splice.c:412 do_splice_to fs/splice.c:871 [inline] splice_direct_to_actor+0x3de/0xb60 fs/splice.c:950 do_splice_direct+0x201/0x340 fs/splice.c:1059 do_sendfile+0x86d/0x1210 fs/read_write.c:1540 __do_sys_sendfile64 fs/read_write.c:1601 [inline] __se_sys_sendfile64 fs/read_write.c:1587 [inline] __x64_sys_sendfile64+0x164/0x1a0 fs/read_write.c:1587 do_syscall_64+0x31/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xa9 -> #1 (sb_writers#4){.+.+}-{0:0}: lock_acquire+0x140/0x6f0 kernel/locking/lockdep.c:5006 percpu_down_read include/linux/percpu-rwsem.h:51 [inline] __sb_start_write+0x14b/0x410 fs/super.c:1672 sb_start_write include/linux/fs.h:1643 [inline] mnt_want_write+0x45/0x90 fs/namespace.c:354 ovl_create_object+0xb1/0x2b0 fs/overlayfs/dir.c:625 lookup_open fs/namei.c:3103 [inline] open_last_lookups fs/namei.c:3177 [inline] path_openat+0x17e1/0x3840 fs/namei.c:3365 do_filp_open+0x191/0x3a0 fs/namei.c:3395 do_sys_openat2+0x463/0x830 fs/open.c:1168 do_sys_open fs/open.c:1184 [inline] __do_sys_open fs/open.c:1192 [inline] __se_sys_open fs/open.c:1188 [inline] __x64_sys_open+0x1af/0x1e0 fs/open.c:1188 do_syscall_64+0x31/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xa9 -> #0 (&ovl_i_mutex_dir_key[depth]){++++}-{3:3}: check_prev_add kernel/locking/lockdep.c:2496 [inline] check_prevs_add kernel/locking/lockdep.c:2601 [inline] validate_chain+0x1b0c/0x88a0 kernel/locking/lockdep.c:3218 __lock_acquire+0x110b/0x2ae0 kernel/locking/lockdep.c:4426 lock_acquire+0x140/0x6f0 kernel/locking/lockdep.c:5006 down_read+0x36/0x50 kernel/locking/rwsem.c:1492 inode_lock_shared include/linux/fs.h:789 [inline] lookup_slow fs/namei.c:1560 [inline] walk_component+0x435/0x680 fs/namei.c:1860 lookup_last fs/namei.c:2309 [inline] path_lookupat+0x19d/0x960 fs/namei.c:2333 filename_lookup+0x1ab/0x5d0 fs/namei.c:2366 create_local_trace_uprobe+0x3f/0x5f0 kernel/trace/trace_uprobe.c:1574 perf_uprobe_init+0xfe/0x1a0 kernel/trace/trace_event_perf.c:323 perf_uprobe_event_init+0xfe/0x180 kernel/events/core.c:9580 perf_try_init_event+0x13e/0x3a0 kernel/events/core.c:10899 perf_init_event kernel/events/core.c:10951 [inline] perf_event_alloc+0xda1/0x28f0 kernel/events/core.c:11229 __do_sys_perf_event_open kernel/events/core.c:11724 [inline] __se_sys_perf_event_open+0x6e7/0x3f60 kernel/events/core.c:11598 do_syscall_64+0x31/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xa9 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.1/5833: #0: ffff8880a65c6c88 (&sig->exec_update_mutex){+.+.}-{3:3}, at: __do_sys_perf_event_open kernel/events/core.c:11704 [inline] #0: ffff8880a65c6c88 (&sig->exec_update_mutex){+.+.}-{3:3}, at: __se_sys_perf_event_open+0xc8b/0x3f60 kernel/events/core.c:11598 #1: ffffffff8b8461a0 (&pmus_srcu){....}-{0:0}, at: rcu_lock_acquire+0x9/0x30 include/linux/rcupdate.h:241 stack backtrace: CPU: 1 PID: 5833 Comm: syz-executor.1 Not tainted 5.9.0-rc3-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+0x1d6/0x29e lib/dump_stack.c:118 print_circular_bug+0xc72/0xea0 kernel/locking/lockdep.c:1703 check_noncircular+0x1fb/0x3a0 kernel/locking/lockdep.c:1827 check_prev_add kernel/locking/lockdep.c:2496 [inline] check_prevs_add kernel/locking/lockdep.c:2601 [inline] validate_chain+0x1b0c/0x88a0 kernel/locking/lockdep.c:3218 __lock_acquire+0x110b/0x2ae0 kernel/locking/lockdep.c:4426 lock_acquire+0x140/0x6f0 kernel/locking/lockdep.c:5006 down_read+0x36/0x50 kernel/locking/rwsem.c:1492 inode_lock_shared include/linux/fs.h:789 [inline] lookup_slow fs/namei.c:1560 [inline] walk_component+0x435/0x680 fs/namei.c:1860 lookup_last fs/namei.c:2309 [inline] path_lookupat+0x19d/0x960 fs/namei.c:2333 filename_lookup+0x1ab/0x5d0 fs/namei.c:2366 create_local_trace_uprobe+0x3f/0x5f0 kernel/trace/trace_uprobe.c:1574 perf_uprobe_init+0xfe/0x1a0 kernel/trace/trace_event_perf.c:323 perf_uprobe_event_init+0xfe/0x180 kernel/events/core.c:9580 perf_try_init_event+0x13e/0x3a0 kernel/events/core.c:10899 perf_init_event kernel/events/core.c:10951 [inline] perf_event_alloc+0xda1/0x28f0 kernel/events/core.c:11229 __do_sys_perf_event_open kernel/events/core.c:11724 [inline] __se_sys_perf_event_open+0x6e7/0x3f60 kernel/events/core.c:11598 do_syscall_64+0x31/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x45d5b9 Code: 5d b4 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 2b b4 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007f9579cebc78 EFLAGS: 00000246 ORIG_RAX: 000000000000012a RAX: ffffffffffffffda RBX: 0000000000024780 RCX: 000000000045d5b9 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000020000180 RBP: 000000000118d170 R08: 0000000000000000 R09: 0000000000000000 R10: ffffffffffffffff R11: 0000000000000246 R12: 000000000118d12c R13: 00007ffe3873fbaf R14: 00007f9579cec9c0 R15: 000000000118d12c