syzbot

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BUG: KCSAN: data-race in __dentry_kill / d_make_discardable

write to 0xffff88811d67e180 of 4 bytes by task 7209 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+0x97f/0xad0 fs/namei.c:5929
 do_renameat2+0x383/0x810 fs/namei.c:6047
 __do_sys_rename fs/namei.c:6090 [inline]
 __se_sys_rename fs/namei.c:6088 [inline]
 __x64_sys_rename+0x58/0x70 fs/namei.c:6088
 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+0xca/0x2b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff88811d67e180 of 4 bytes by task 6501 on cpu 1:
 dentry_unlist fs/dcache.c:640 [inline]
 __dentry_kill+0x2aa/0x4b0 fs/dcache.c:684
 finish_dput+0x2b/0x200 fs/dcache.c:879
 dput+0x52/0x60 fs/dcache.c:928
 end_renaming fs/namei.c:4052 [inline]
 do_renameat2+0x44a/0x810 fs/namei.c:6049
 __do_sys_rename fs/namei.c:6090 [inline]
 __se_sys_rename fs/namei.c:6088 [inline]
 __x64_sys_rename+0x58/0x70 fs/namei.c:6088
 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+0xca/0x2b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x08200080 -> 0x00200180

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 6501 Comm: udevd Tainted: G        W           syzkaller #0 PREEMPT(voluntary) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
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