syzbot

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BUG: KCSAN: data-race in __d_instantiate / lookup_fast

read-write to 0xffff88810695d3c0 of 4 bytes by task 4930 on cpu 1:
 __d_instantiate+0x2cd/0x3c0 fs/dcache.c:1855
 d_instantiate_new+0x5c/0xf0 fs/dcache.c:1899
 ext4_add_nondir+0x16c/0x1a0 fs/ext4/namei.c:2797
 ext4_mknod+0x210/0x2f0 fs/ext4/namei.c:2872
 vfs_mknod+0x2d4/0x310 fs/namei.c:4001
 do_mknodat+0x27b/0x420
 __do_sys_mknod fs/namei.c:4084 [inline]
 __se_sys_mknod fs/namei.c:4082 [inline]
 __x64_sys_mknod+0x53/0x60 fs/namei.c:4082
 x64_sys_call+0x9af/0x2d30 arch/x86/include/generated/asm/syscalls_64.h:134
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x1d0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff88810695d3c0 of 4 bytes by task 4928 on cpu 0:
 d_revalidate fs/namei.c:860 [inline]
 lookup_fast+0xd9/0x2a0 fs/namei.c:1641
 open_last_lookups fs/namei.c:3534 [inline]
 path_openat+0x44c/0x1d80 fs/namei.c:3796
 do_filp_open+0xf7/0x200 fs/namei.c:3826
 do_sys_openat2+0xab/0x120 fs/open.c:1406
 do_sys_open fs/open.c:1421 [inline]
 __do_sys_open fs/open.c:1429 [inline]
 __se_sys_open fs/open.c:1425 [inline]
 __x64_sys_open+0xe6/0x110 fs/open.c:1425
 x64_sys_call+0x12ae/0x2d30 arch/x86/include/generated/asm/syscalls_64.h:3
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x1d0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00080000 -> 0x00580040

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 4928 Comm: syz-executor.0 Tainted: G        W          6.9.0-rc7-syzkaller-00188-gba16c1cf11c9 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/02/2024
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