selftests/damon/wss_estimation: test for up to 160 MiB working set size

selftests/damon/wss_estimation: test for up to 160 MiB working set size

DAMON reads and writes Accessed bits of page tables without manual TLB
flush for two reasons.  First, it minimizes the overhead.  Second, real
systems that need DAMON are expected to be memory intensive enough to
cause periodic TLB flushes.  For test setups that use small test
workloads, however, the system's TLB could be big enough to cover whole or
most accesses of the test workload.  In this case, no page table walk
happens and DAMON cannot show any access from the test workload.

The test workload for DAMON's working set size estimation selftest is such
a case.  It accesses only 10 MiB working set, and it turned out there are
test setups that have TLBs large enough to cover the 10 MiB data accesses.
As a result, the test fails depending on the test machine.

Make it more reliable by trying larger working sets up to 160 MiB when it
fails.

Link: https://lkml.kernel.org/r/20260117020731.226785-3-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>