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BUG: KCSAN: data-race in __d_instantiate / path_lookupat

write to 0xffff88810707e0f0 of 8 bytes by task 11905 on cpu 1:
 __d_set_inode_and_type fs/dcache.c:407 [inline]
 __d_instantiate+0x1db/0x390 fs/dcache.c:2147
 d_make_persistent+0x72/0x110 fs/dcache.c:2973
 shmem_mknod+0x15f/0x170 mm/shmem.c:3827
 shmem_mkdir+0x33/0x70 mm/shmem.c:3869
 vfs_mkdir+0x28a/0x3e0 fs/namei.c:5276
 filename_mkdirat+0x138/0x300 fs/namei.c:5309
 __do_sys_mkdirat fs/namei.c:5330 [inline]
 __se_sys_mkdirat+0x32/0xf0 fs/namei.c:5327
 __x64_sys_mkdirat+0x43/0x50 fs/namei.c:5327
 x64_sys_call+0x2c4e/0x3020 arch/x86/include/generated/asm/syscalls_64.h:259
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x136/0x3c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff88810707e0f0 of 8 bytes by task 11906 on cpu 0:
 step_into fs/namei.c:2141 [inline]
 walk_component fs/namei.c:2288 [inline]
 lookup_last fs/namei.c:2789 [inline]
 path_lookupat+0x1eb/0x4c0 fs/namei.c:2813
 filename_lookup+0x18f/0x390 fs/namei.c:2842
 user_path_at+0x3e/0x100 fs/namei.c:3641
 do_mount fs/namespace.c:4171 [inline]
 __do_sys_mount fs/namespace.c:4390 [inline]
 __se_sys_mount+0x25b/0x2e0 fs/namespace.c:4367
 __x64_sys_mount+0x67/0x80 fs/namespace.c:4367
 x64_sys_call+0x2d61/0x3020 arch/x86/include/generated/asm/syscalls_64.h:166
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x136/0x3c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0000000000000000 -> 0xffff88811b7c0b60

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 11906 Comm: syz.0.2818 Not tainted syzkaller #0 PREEMPT(lazy) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
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