====================================================== WARNING: possible circular locking dependency detected 5.0.0-rc3-next-20190125 #20 Not tainted ------------------------------------------------------ syz-executor0/6351 is trying to acquire lock: 0000000088dd4d6a (&ovl_i_mutex_dir_key[depth]){++++}, at: inode_lock_shared include/linux/fs.h:769 [inline] 0000000088dd4d6a (&ovl_i_mutex_dir_key[depth]){++++}, at: lookup_slow+0x4a/0x80 fs/namei.c:1687 but task is already holding lock: 00000000cd43a207 (&sig->cred_guard_mutex){+.+.}, at: __do_sys_perf_event_open+0x99b/0x3030 kernel/events/core.c:10520 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #3 (&sig->cred_guard_mutex){+.+.}: __mutex_lock_common kernel/locking/mutex.c:925 [inline] __mutex_lock+0x12f/0x1670 kernel/locking/mutex.c:1072 mutex_lock_killable_nested+0x16/0x20 kernel/locking/mutex.c:1102 lock_trace+0x4a/0xe0 fs/proc/base.c:388 proc_pid_syscall+0x9d/0x4b0 fs/proc/base.c:623 proc_single_show+0xf6/0x180 fs/proc/base.c:743 seq_read+0x4db/0x1130 fs/seq_file.c:229 do_loop_readv_writev fs/read_write.c:700 [inline] do_loop_readv_writev fs/read_write.c:687 [inline] do_iter_read+0x4a9/0x660 fs/read_write.c:921 vfs_readv+0x175/0x1c0 fs/read_write.c:983 kernel_readv fs/splice.c:362 [inline] default_file_splice_read+0x50c/0xac0 fs/splice.c:417 do_splice_to+0x12a/0x190 fs/splice.c:880 splice_direct_to_actor+0x31b/0x9d0 fs/splice.c:957 do_splice_direct+0x2c7/0x420 fs/splice.c:1066 do_sendfile+0x61a/0xe60 fs/read_write.c:1436 __do_sys_sendfile64 fs/read_write.c:1497 [inline] __se_sys_sendfile64 fs/read_write.c:1483 [inline] __x64_sys_sendfile64+0x1f8/0x240 fs/read_write.c:1483 do_syscall_64+0x1a3/0x800 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #2 (&p->lock){+.+.}: __mutex_lock_common kernel/locking/mutex.c:925 [inline] __mutex_lock+0x12f/0x1670 kernel/locking/mutex.c:1072 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1087 seq_read+0x71/0x1130 fs/seq_file.c:161 do_loop_readv_writev fs/read_write.c:700 [inline] do_loop_readv_writev fs/read_write.c:687 [inline] do_iter_read+0x4a9/0x660 fs/read_write.c:921 vfs_readv+0x175/0x1c0 fs/read_write.c:983 kernel_readv fs/splice.c:362 [inline] default_file_splice_read+0x50c/0xac0 fs/splice.c:417 do_splice_to+0x12a/0x190 fs/splice.c:880 splice_direct_to_actor+0x31b/0x9d0 fs/splice.c:957 do_splice_direct+0x2c7/0x420 fs/splice.c:1066 do_sendfile+0x61a/0xe60 fs/read_write.c:1436 __do_sys_sendfile64 fs/read_write.c:1491 [inline] __se_sys_sendfile64 fs/read_write.c:1483 [inline] __x64_sys_sendfile64+0x15a/0x240 fs/read_write.c:1483 do_syscall_64+0x1a3/0x800 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #1 (sb_writers#3){.+.+}: percpu_down_read_preempt_disable include/linux/percpu-rwsem.h:36 [inline] percpu_down_read include/linux/percpu-rwsem.h:59 [inline] __sb_start_write+0x20b/0x360 fs/super.c:1613 sb_start_write include/linux/fs.h:1605 [inline] mnt_want_write+0x3f/0xc0 fs/namespace.c:358 ovl_want_write+0x76/0xa0 fs/overlayfs/util.c:24 ovl_create_object+0x146/0x3b0 fs/overlayfs/dir.c:599 ovl_create+0x28/0x30 fs/overlayfs/dir.c:630 lookup_open+0x1332/0x1b80 fs/namei.c:3234 do_last fs/namei.c:3324 [inline] path_openat+0x1983/0x5660 fs/namei.c:3535 do_filp_open+0x26f/0x370 fs/namei.c:3565 do_sys_open+0x59a/0x7c0 fs/open.c:1063 __do_sys_open fs/open.c:1081 [inline] __se_sys_open fs/open.c:1076 [inline] __x64_sys_open+0x7e/0xc0 fs/open.c:1076 do_syscall_64+0x1a3/0x800 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #0 (&ovl_i_mutex_dir_key[depth]){++++}: lock_acquire+0x1db/0x570 kernel/locking/lockdep.c:3845 down_read+0x8d/0x120 kernel/locking/rwsem.c:24 inode_lock_shared include/linux/fs.h:769 [inline] lookup_slow+0x4a/0x80 fs/namei.c:1687 walk_component+0x8e5/0x26a0 fs/namei.c:1810 lookup_last fs/namei.c:2273 [inline] path_lookupat.isra.0+0x1f5/0xba0 fs/namei.c:2318 filename_lookup+0x27a/0x530 fs/namei.c:2348 kern_path+0x36/0x40 fs/namei.c:2434 create_local_trace_uprobe+0x93/0x610 kernel/trace/trace_uprobe.c:1357 perf_uprobe_init+0x1a2/0x290 kernel/trace/trace_event_perf.c:316 perf_uprobe_event_init+0x106/0x1a0 kernel/events/core.c:8503 perf_try_init_event+0x137/0x3f0 kernel/events/core.c:9770 perf_init_event kernel/events/core.c:9810 [inline] perf_event_alloc.part.0+0x22dc/0x3450 kernel/events/core.c:10083 perf_event_alloc kernel/events/core.c:10439 [inline] __do_sys_perf_event_open+0xb86/0x3030 kernel/events/core.c:10540 __se_sys_perf_event_open kernel/events/core.c:10429 [inline] __x64_sys_perf_event_open+0xbe/0x150 kernel/events/core.c:10429 do_syscall_64+0x1a3/0x800 arch/x86/entry/common.c:290 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-executor0/6351: #0: 00000000cd43a207 (&sig->cred_guard_mutex){+.+.}, at: __do_sys_perf_event_open+0x99b/0x3030 kernel/events/core.c:10520 #1: 00000000f53d73ae (&pmus_srcu){....}, at: perf_event_alloc.part.0+0x1048/0x3450 kernel/events/core.c:10079 stack backtrace: CPU: 1 PID: 6351 Comm: syz-executor0 Not tainted 5.0.0-rc3-next-20190125 #20 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+0x1db/0x2d0 lib/dump_stack.c:113 print_circular_bug.isra.0.cold+0x1cc/0x28f kernel/locking/lockdep.c:1225 check_prev_add kernel/locking/lockdep.c:1856 [inline] check_prevs_add kernel/locking/lockdep.c:1969 [inline] validate_chain kernel/locking/lockdep.c:2340 [inline] __lock_acquire+0x2fed/0x4a10 kernel/locking/lockdep.c:3321 lock_acquire+0x1db/0x570 kernel/locking/lockdep.c:3845 down_read+0x8d/0x120 kernel/locking/rwsem.c:24 inode_lock_shared include/linux/fs.h:769 [inline] lookup_slow+0x4a/0x80 fs/namei.c:1687 walk_component+0x8e5/0x26a0 fs/namei.c:1810 lookup_last fs/namei.c:2273 [inline] path_lookupat.isra.0+0x1f5/0xba0 fs/namei.c:2318 filename_lookup+0x27a/0x530 fs/namei.c:2348 kern_path+0x36/0x40 fs/namei.c:2434 create_local_trace_uprobe+0x93/0x610 kernel/trace/trace_uprobe.c:1357 perf_uprobe_init+0x1a2/0x290 kernel/trace/trace_event_perf.c:316 perf_uprobe_event_init+0x106/0x1a0 kernel/events/core.c:8503 perf_try_init_event+0x137/0x3f0 kernel/events/core.c:9770 perf_init_event kernel/events/core.c:9810 [inline] perf_event_alloc.part.0+0x22dc/0x3450 kernel/events/core.c:10083 perf_event_alloc kernel/events/core.c:10439 [inline] __do_sys_perf_event_open+0xb86/0x3030 kernel/events/core.c:10540 __se_sys_perf_event_open kernel/events/core.c:10429 [inline] __x64_sys_perf_event_open+0xbe/0x150 kernel/events/core.c:10429 do_syscall_64+0x1a3/0x800 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x458099 Code: 6d 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 3b b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007fa24c1c6c78 EFLAGS: 00000246 ORIG_RAX: 000000000000012a RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 0000000000458099 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000020000180 RBP: 000000000073bf00 R08: 0000000000000000 R09: 0000000000000000 R10: ffffffffffffffff R11: 0000000000000246 R12: 00007fa24c1c76d4 R13: 00000000004c46c5 R14: 00000000004d7cc8 R15: 00000000ffffffff