DF-0779 PATH A: local getdents on tmpfs dir /tmp/df0779_export
Testing attacker-supplied bogus/huge/negative cookies via lseek+getdents.
(If this panics, the local-unpriv DoS claim holds. Source says it should NOT.
Surviving all of these => cookies block not reached locally.)

[cookie=0xdead] getdents rc=0 errno=0 (ok) entries=0
[cookie=0x7fffffffffffffff] getdents rc=0 errno=0 (ok) entries=0
[cookie=0x4141414141414141] getdents rc=0 errno=0 (ok) entries=0
[cookie=0xffffffffffffffff] lseek failed: Invalid argument
[cookie=0x8000000000000000] lseek failed: Invalid argument
[cookie=0x2] getdents rc=0 errno=0 (ok) entries=0
[cookie=0xbadf00d] getdents rc=0 errno=0 (ok) entries=0

All cookie probes returned without panic.