HWPOISON, hugetlb: set/clear PG_hwpoison bits on hugepage
To avoid race condition between concurrent memory errors on identified
hugepage, we atomically test and set PG_hwpoison bit on the head page.
All pages in the error hugepage are considered as hwpoisoned
for now, so set and clear all PG_hwpoison bits in the hugepage
with page lock of the head page held.
Dependency:
"HWPOISON, hugetlb: enable error handling path for hugepage"