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BUG: KCSAN: data-race in __d_instantiate / step_into

write to 0xffff8881057d1630 of 8 bytes by task 9773 on cpu 0:
 __d_set_inode_and_type fs/dcache.c:344 [inline]
 __d_instantiate+0x1fb/0x3c0 fs/dcache.c:1859
 d_instantiate+0x59/0x80 fs/dcache.c:1886
 shmem_mknod+0x153/0x180 mm/shmem.c:3298
 shmem_mkdir+0x33/0x70 mm/shmem.c:3340
 vfs_mkdir+0x1f4/0x320 fs/namei.c:4137
 do_mkdirat+0x12f/0x2a0 fs/namei.c:4160
 __do_sys_mkdirat fs/namei.c:4175 [inline]
 __se_sys_mkdirat fs/namei.c:4173 [inline]
 __x64_sys_mkdirat+0x50/0x60 fs/namei.c:4173
 x64_sys_call+0x2ce5/0x2d70 arch/x86/include/generated/asm/syscalls_64.h:259
 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 0xffff8881057d1630 of 8 bytes by task 9774 on cpu 1:
 step_into+0x123/0x810 fs/namei.c:1846
 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
 user_path_at_empty+0x42/0x120 fs/namei.c:2929
 user_path_at include/linux/namei.h:58 [inline]
 __do_sys_chdir fs/open.c:558 [inline]
 __se_sys_chdir+0x4f/0x150 fs/open.c:552
 __x64_sys_chdir+0x1f/0x30 fs/open.c:552
 x64_sys_call+0x2b05/0x2d70 arch/x86/include/generated/asm/syscalls_64.h:81
 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: 0x0000000000000000 -> 0xffff888113354950

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 9774 Comm: syz.1.2118 Tainted: G        W          6.10.0-rc7-syzkaller-00254-g528dd46d0fc3 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/07/2024
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