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BUG: KCSAN: data-race in __d_instantiate / step_into

read-write to 0xffff888105486900 of 4 bytes by task 25 on cpu 0:
 fsnotify_update_flags include/linux/fsnotify_backend.h:-1 [inline]
 __d_instantiate+0x2c2/0x3b0 fs/dcache.c:1922
 d_instantiate+0x59/0x80 fs/dcache.c:1947
 shmem_mknod+0x153/0x180 mm/shmem.c:3863
 vfs_mknod+0x2cb/0x310 fs/namei.c:4235
 handle_create drivers/base/devtmpfs.c:233 [inline]
 handle drivers/base/devtmpfs.c:389 [inline]
 devtmpfs_work_loop+0x67d/0x840 drivers/base/devtmpfs.c:404
 devtmpfsd+0x48/0x50 drivers/base/devtmpfs.c:446
 kthread+0x486/0x510 kernel/kthread.c:464
 ret_from_fork+0xda/0x150 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

read to 0xffff888105486900 of 4 bytes by task 23578 on cpu 1:
 __d_entry_type include/linux/dcache.h:409 [inline]
 d_is_symlink include/linux/dcache.h:439 [inline]
 step_into+0x12f/0x820 fs/namei.c:1981
 open_last_lookups fs/namei.c:3834 [inline]
 path_openat+0x13e8/0x2170 fs/namei.c:4043
 do_filp_open+0x109/0x230 fs/namei.c:4073
 do_sys_openat2+0xa6/0x110 fs/open.c:1437
 do_sys_open fs/open.c:1452 [inline]
 __do_sys_openat fs/open.c:1468 [inline]
 __se_sys_openat fs/open.c:1463 [inline]
 __x64_sys_openat+0xf2/0x120 fs/open.c:1463
 x64_sys_call+0x1af/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:258
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00000008 -> 0x00280008

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 23578 Comm: syz.4.7125 Not tainted 6.15.0-syzkaller-13743-g8630c59e9936 #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
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