syzbot

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BUG: KCSAN: data-race in list_lru_add / list_lru_count_node

write to 0xffff8881009c4828 of 8 bytes by task 3744 on cpu 1:
 list_lru_add+0x26d/0x2c0 mm/list_lru.c:130
 d_lru_add fs/dcache.c:406 [inline]
 retain_dentry+0x226/0x260 fs/dcache.c:660
 dput+0x3d/0x360 fs/dcache.c:883
 handle_mounts fs/namei.c:1474 [inline]
 step_into+0x442/0xec0 fs/namei.c:1772
 open_last_lookups fs/namei.c:3308 [inline]
 path_openat+0xfc8/0x20b0 fs/namei.c:3491
 do_filp_open+0xd9/0x1f0 fs/namei.c:3521
 do_open_execat+0xd6/0x3c0 fs/exec.c:913
 bprm_execve+0x2c7/0x530 fs/exec.c:1805
 kernel_execve+0x61b/0x640 fs/exec.c:1973
 call_usermodehelper_exec_async+0x1d8/0x290 kernel/umh.c:112
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294

read to 0xffff8881009c4828 of 8 bytes by task 3742 on cpu 0:
 list_lru_count_node+0x28/0x30 mm/list_lru.c:195
 list_lru_count include/linux/list_lru.h:132 [inline]
 shrink_dcache_sb+0x1ed/0x2d0 fs/dcache.c:1297
 reconfigure_super+0x2aa/0x4f0 fs/super.c:889
 do_remount fs/namespace.c:2639 [inline]
 path_mount+0x1442/0x1ce0 fs/namespace.c:3227
 do_mount fs/namespace.c:3248 [inline]
 __do_sys_mount fs/namespace.c:3456 [inline]
 __se_sys_mount+0x23d/0x2e0 fs/namespace.c:3433
 __x64_sys_mount+0x63/0x70 fs/namespace.c:3433
 do_syscall_64+0x4a/0x90 arch/x86/entry/common.c:47
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 3742 Comm: syz-executor.2 Tainted: G        W         5.13.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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