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BUG: KCSAN: data-race in __d_instantiate / step_into

read-write to 0xffff88811926ee40 of 4 bytes by task 13399 on cpu 0:
 __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:4009
 unix_bind_bsd net/unix/af_unix.c:1223 [inline]
 unix_bind+0x2de/0x870 net/unix/af_unix.c:1316
 __sys_bind+0x15b/0x1d0 net/socket.c:1847
 __do_sys_bind net/socket.c:1858 [inline]
 __se_sys_bind net/socket.c:1856 [inline]
 __x64_sys_bind+0x41/0x50 net/socket.c:1856
 x64_sys_call+0x25b5/0x2d70 arch/x86/include/generated/asm/syscalls_64.h:50
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff88811926ee40 of 4 bytes by task 13400 on cpu 1:
 __d_entry_type include/linux/dcache.h:397 [inline]
 d_is_symlink include/linux/dcache.h:427 [inline]
 step_into+0x12f/0x810 fs/namei.c:1847
 walk_component+0x169/0x230 fs/namei.c:2010
 lookup_last fs/namei.c:2469 [inline]
 path_lookupat+0x10a/0x2b0 fs/namei.c:2493
 filename_lookup+0x127/0x300 fs/namei.c:2522
 kern_path+0x39/0x110 fs/namei.c:2630
 unix_find_bsd net/unix/af_unix.c:1058 [inline]
 unix_find_other+0x88/0x550 net/unix/af_unix.c:1119
 unix_dgram_connect+0x2c5/0x830 net/unix/af_unix.c:1376
 __sys_connect_file net/socket.c:2049 [inline]
 __sys_connect+0x1a9/0x1c0 net/socket.c:2066
 __do_sys_connect net/socket.c:2076 [inline]
 __se_sys_connect net/socket.c:2073 [inline]
 __x64_sys_connect+0x41/0x50 net/socket.c:2073
 x64_sys_call+0x2961/0x2d70 arch/x86/include/generated/asm/syscalls_64.h:43
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00000000 -> 0x00500000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 13400 Comm: syz.4.3294 Not tainted 6.10.0-rc5-syzkaller-00012-g626737a5791b #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/07/2024
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