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BUG: KCSAN: data-race in d_make_discardable / lookup_fast

write to 0xffff88811a976f00 of 4 bytes by task 3306 on cpu 0:
 d_make_discardable+0x4f/0xa0 fs/dcache.c:936
 simple_unlink+0x68/0x80 fs/libfs.c:807
 shmem_unlink+0x12d/0x140 mm/shmem.c:3991
 shmem_rename2+0x18e/0x310 mm/shmem.c:4072
 vfs_rename+0xa9e/0xbf0 fs/namei.c:5938
 do_renameat2+0x39a/0x850 fs/namei.c:6056
 __do_sys_rename fs/namei.c:6099 [inline]
 __se_sys_rename fs/namei.c:6097 [inline]
 __x64_sys_rename+0x58/0x70 fs/namei.c:6097
 x64_sys_call+0x24e/0x3000 arch/x86/include/generated/asm/syscalls_64.h:83
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xc0/0x2a0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff88811a976f00 of 4 bytes by task 3303 on cpu 1:
 d_revalidate fs/namei.c:976 [inline]
 lookup_fast+0xf0/0x320 fs/namei.c:1814
 walk_component fs/namei.c:2225 [inline]
 lookup_last fs/namei.c:2730 [inline]
 path_lookupat+0x15c/0x500 fs/namei.c:2754
 filename_lookup+0x190/0x390 fs/namei.c:2783
 vfs_statx+0x96/0x170 fs/stat.c:353
 vfs_fstatat+0x115/0x170 fs/stat.c:375
 __do_sys_newfstatat fs/stat.c:542 [inline]
 __se_sys_newfstatat+0x55/0x3e0 fs/stat.c:536
 __x64_sys_newfstatat+0x55/0x70 fs/stat.c:536
 x64_sys_call+0x111f/0x3000 arch/x86/include/generated/asm/syscalls_64.h:263
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xc0/0x2a0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x08300080 -> 0x00300180

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 3303 Comm: udevd Not tainted syzkaller #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
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