syzbot

cgroup: Unknown subsys name 'perf_event'
cgroup: Unknown subsys name 'net_cls'
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BUG: KCSAN: data-race in __d_rehash / retain_dentry

write to 0xffff888105c1b910 of 8 bytes by task 1758 on cpu 0:
 hlist_bl_add_head_rcu include/linux/rculist_bl.h:81 [inline]
 __d_rehash+0xaf/0x180 fs/dcache.c:2517
 __d_add+0x345/0x490 fs/dcache.c:2711
 d_splice_alias+0xd9/0x4f0 fs/dcache.c:3098
 proc_sys_lookup+0x421/0x550 fs/proc/proc_sysctl.c:530
 lookup_open fs/namei.c:3193 [inline]
 open_last_lookups fs/namei.c:3285 [inline]
 path_openat+0xb5a/0x20b0 fs/namei.c:3491
 do_filp_open+0xd9/0x1f0 fs/namei.c:3521
 do_sys_openat2+0xa3/0x250 fs/open.c:1187
 do_sys_open fs/open.c:1203 [inline]
 __do_sys_openat fs/open.c:1219 [inline]
 __se_sys_openat fs/open.c:1214 [inline]
 __x64_sys_openat+0xef/0x110 fs/open.c:1214
 do_syscall_64+0x4a/0x90 arch/x86/entry/common.c:47
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff888105c1b910 of 8 bytes by task 1759 on cpu 1:
 hlist_bl_unhashed include/linux/list_bl.h:54 [inline]
 d_unhashed include/linux/dcache.h:341 [inline]
 retain_dentry+0x42/0x260 fs/dcache.c:641
 dput+0x3d/0x360 fs/dcache.c:881
 __fput+0x3ab/0x4e0 fs/file_table.c:293
 ____fput+0x11/0x20 fs/file_table.c:313
 task_work_run+0xae/0x130 kernel/task_work.c:161
 tracehook_notify_resume include/linux/tracehook.h:189 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:174 [inline]
 exit_to_user_mode_prepare+0x156/0x190 kernel/entry/common.c:208
 __syscall_exit_to_user_mode_work kernel/entry/common.c:290 [inline]
 syscall_exit_to_user_mode+0x20/0x40 kernel/entry/common.c:301
 do_syscall_64+0x56/0x90 arch/x86/entry/common.c:57
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 1759 Comm: syz-executor.1 Not tainted 5.12.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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