syzbot

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BUG: KCSAN: data-race in __d_instantiate / step_into

write to 0xffff88810658c930 of 8 bytes by task 4181 on cpu 0:
 __d_set_inode_and_type fs/dcache.c:397 [inline]
 __d_instantiate+0x1f8/0x3b0 fs/dcache.c:1911
 d_instantiate+0x59/0x80 fs/dcache.c:1938
 shmem_mknod+0x153/0x180 mm/shmem.c:3864
 shmem_mkdir+0x33/0x70 mm/shmem.c:3907
 vfs_mkdir+0x210/0x340 fs/namei.c:4359
 do_mkdirat+0x132/0x3f0 fs/namei.c:4392
 __do_sys_mkdirat fs/namei.c:4409 [inline]
 __se_sys_mkdirat fs/namei.c:4407 [inline]
 __x64_sys_mkdirat+0x4c/0x60 fs/namei.c:4407
 x64_sys_call+0x2be0/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:259
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd0/0x1a0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff88810658c930 of 8 bytes by task 4175 on cpu 1:
 step_into+0x122/0x820 fs/namei.c:1980
 open_last_lookups fs/namei.c:3827 [inline]
 path_openat+0x13e8/0x2170 fs/namei.c:4036
 do_filp_open+0x109/0x230 fs/namei.c:4066
 io_openat2+0x272/0x390 io_uring/openclose.c:140
 io_openat+0x1b/0x30 io_uring/openclose.c:177
 __io_issue_sqe io_uring/io_uring.c:1740 [inline]
 io_issue_sqe+0x1a8/0xb70 io_uring/io_uring.c:1759
 io_queue_sqe io_uring/io_uring.c:1975 [inline]
 io_submit_sqe io_uring/io_uring.c:2231 [inline]
 io_submit_sqes+0x64c/0x1000 io_uring/io_uring.c:2348
 __do_sys_io_uring_enter io_uring/io_uring.c:3408 [inline]
 __se_sys_io_uring_enter+0x1c1/0x1b70 io_uring/io_uring.c:3342
 __x64_sys_io_uring_enter+0x78/0x90 io_uring/io_uring.c:3342
 x64_sys_call+0x28c8/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:427
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd0/0x1a0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0000000000000000 -> 0xffff8881187f6648

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 4175 Comm: syz.2.193 Not tainted 6.15.0-rc3-syzkaller-00342-g5bc1018675ec #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
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