syzbot

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BUG: KCSAN: data-race in __d_rehash / retain_dentry

write to 0xffff888129e0a850 of 8 bytes by task 25212 on cpu 0:
 hlist_bl_add_head_rcu include/linux/rculist_bl.h:81 [inline]
 __d_rehash+0xc4/0x220 fs/dcache.c:2578
 __d_add+0x36d/0x4a0 fs/dcache.c:2793
 d_splice_alias+0xd6/0x270 fs/dcache.c:3181
 ext4_lookup+0x199/0x390 fs/ext4/namei.c:1883
 lookup_one_qstr_excl+0xc0/0x180 fs/namei.c:1609
 filename_create+0x14d/0x2b0 fs/namei.c:3876
 do_symlinkat+0x84/0x340 fs/namei.c:4483
 __do_sys_symlinkat fs/namei.c:4506 [inline]
 __se_sys_symlinkat fs/namei.c:4503 [inline]
 __x64_sys_symlinkat+0x62/0x70 fs/namei.c:4503
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0x44/0x110 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

read to 0xffff888129e0a850 of 8 bytes by task 25214 on cpu 1:
 hlist_bl_unhashed include/linux/list_bl.h:54 [inline]
 d_unhashed include/linux/dcache.h:336 [inline]
 retain_dentry+0x40/0x190 fs/dcache.c:668
 dput+0x108/0x1f0 fs/dcache.c:908
 __fput+0x41d/0x630 fs/file_table.c:402
 __fput_sync+0x44/0x50 fs/file_table.c:475
 __do_sys_close fs/open.c:1587 [inline]
 __se_sys_close+0xfa/0x1a0 fs/open.c:1572
 __x64_sys_close+0x1f/0x30 fs/open.c:1572
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0x44/0x110 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

value changed: 0xffff888237a3dca8 -> 0xffff88812358d308

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 25214 Comm: syz-executor.4 Not tainted 6.7.0-rc6-syzkaller-00010-g2cf4f94d8e86 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/17/2023
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