syzbot

ref_ctr going negative. vaddr: 0x20000008, curr val: 0, delta: -1
ref_ctr decrement failed for inode: 0x361d offset: 0x0 ref_ctr_offset: 0x8 of mm: 0x000000007e619a8a
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BUG: KCSAN: data-race in exit_signals / task_dump_owner

write to 0xffff8881227c20ac of 4 bytes by task 23209 on cpu 1:
 exit_signals+0xe1/0x4a0 kernel/signal.c:2927
 do_exit+0x194/0x1560 kernel/exit.c:782
 do_group_exit+0x19b/0x1a0 kernel/exit.c:923
 __do_sys_exit_group+0xb/0x10 kernel/exit.c:934
 __se_sys_exit_group+0x5/0x10 kernel/exit.c:932
 __x64_sys_exit_group+0x16/0x20 kernel/exit.c:932
 do_syscall_64+0x4a/0x90 arch/x86/entry/common.c:47
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff8881227c20ac of 4 bytes by task 23217 on cpu 0:
 task_dump_owner+0x2b/0x1d0 fs/proc/base.c:1822
 pid_update_inode fs/proc/base.c:1964 [inline]
 pid_revalidate+0x69/0x110 fs/proc/base.c:1987
 lookup_fast+0x1fd/0x350 fs/namei.c:827
 walk_component+0x5c/0x350 fs/namei.c:1938
 link_path_walk+0x4ba/0x780 fs/namei.c:2265
 path_lookupat+0x7b/0x570 fs/namei.c:2420
 filename_lookup+0xff/0x390 fs/namei.c:2454
 kern_path+0x2e/0x40 fs/namei.c:2541
 create_local_trace_uprobe+0x3f/0x3c0 kernel/trace/trace_uprobe.c:1592
 perf_uprobe_init+0xbe/0x140 kernel/trace/trace_event_perf.c:323
 perf_uprobe_event_init+0xde/0x140 kernel/events/core.c:9868
 perf_try_init_event+0x21a/0x400 kernel/events/core.c:11185
 perf_init_event kernel/events/core.c:11249 [inline]
 perf_event_alloc+0xa60/0x1790 kernel/events/core.c:11540
 __do_sys_perf_event_open kernel/events/core.c:12029 [inline]
 __se_sys_perf_event_open+0x5c7/0x2740 kernel/events/core.c:11921
 __x64_sys_perf_event_open+0x63/0x70 kernel/events/core.c:11921
 do_syscall_64+0x4a/0x90 arch/x86/entry/common.c:47
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0x00404040 -> 0x00404044

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 23217 Comm: syz-executor.1 Not tainted 5.13.0-rc4-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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