syzbot

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BUG: KCSAN: data-race in d_lru_add / lookup_fast

read to 0xffff8881255d2a80 of 4 bytes by task 7971 on cpu 0:
 d_is_miss include/linux/dcache.h:394 [inline]
 d_is_negative include/linux/dcache.h:440 [inline]
 lookup_fast+0xdf/0x6c0 fs/namei.c:1581
 walk_component+0x6d/0xd90 fs/namei.c:1798
 link_path_walk.part.0+0x5d3/0xa90 fs/namei.c:2128
 link_path_walk fs/namei.c:2059 [inline]
 path_openat+0x14f/0x3580 fs/namei.c:3536
 do_filp_open+0x11e/0x1b0 fs/namei.c:3567
 do_sys_open+0x3b3/0x4f0 fs/open.c:1097
 __do_sys_open fs/open.c:1115 [inline]
 __se_sys_open fs/open.c:1110 [inline]
 __x64_sys_open+0x55/0x70 fs/open.c:1110
 do_syscall_64+0xcc/0x3a0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

write to 0xffff8881255d2a80 of 4 bytes by task 7975 on cpu 1:
 d_lru_add+0x56/0xf0 fs/dcache.c:400
 retain_dentry fs/dcache.c:653 [inline]
 dput+0x417/0x750 fs/dcache.c:854
 path_put_conditional fs/namei.c:821 [inline]
 follow_managed+0x1eb/0x6f0 fs/namei.c:1279
 walk_component+0x4ec/0xd90 fs/namei.c:1808
 link_path_walk.part.0+0x5d3/0xa90 fs/namei.c:2128
 link_path_walk fs/namei.c:2059 [inline]
 path_openat+0x14f/0x3580 fs/namei.c:3536
 do_filp_open+0x11e/0x1b0 fs/namei.c:3567
 do_sys_open+0x3b3/0x4f0 fs/open.c:1097
 __do_sys_open fs/open.c:1115 [inline]
 __se_sys_open fs/open.c:1110 [inline]
 __x64_sys_open+0x55/0x70 fs/open.c:1110
 do_syscall_64+0xcc/0x3a0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 7975 Comm: modprobe Not tainted 5.5.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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