From: Anshuman Khandual <[email protected]> Currently hugepage migrated by soft-offline (i.e. due to correctable memory errors) is contained as a hugepage, which means many non-error pages in it are unreusable, i.e. wasted.
This patch solves this issue by dissolving source hugepages into buddy. As done in previous patch, PageHWPoison is set only on a head page of the error hugepage. Then in dissoliving we move the PageHWPoison flag to the raw error page so that all healthy subpages return back to buddy. Signed-off-by: Anshuman Khandual <[email protected]> Signed-off-by: Naoya Horiguchi <[email protected]> --- include/linux/hugetlb.h | 2 ++ mm/hugetlb.c | 10 +++++++++- mm/memory-failure.c | 5 +---- mm/migrate.c | 2 ++ 4 files changed, 14 insertions(+), 5 deletions(-) diff --git v4.12-rc3/include/linux/hugetlb.h v4.12-rc3_patched/include/linux/hugetlb.h index b857fc8..89afe40 100644 --- v4.12-rc3/include/linux/hugetlb.h +++ v4.12-rc3_patched/include/linux/hugetlb.h @@ -461,6 +461,7 @@ static inline pgoff_t basepage_index(struct page *page) return __basepage_index(page); } +extern int dissolve_free_huge_page(struct page *page); extern int dissolve_free_huge_pages(unsigned long start_pfn, unsigned long end_pfn); static inline bool hugepage_migration_supported(struct hstate *h) @@ -529,6 +530,7 @@ static inline pgoff_t basepage_index(struct page *page) { return page->index; } +#define dissolve_free_huge_page(p) 0 #define dissolve_free_huge_pages(s, e) 0 #define hugepage_migration_supported(h) false diff --git v4.12-rc3/mm/hugetlb.c v4.12-rc3_patched/mm/hugetlb.c index 6d6c659..41c37ed 100644 --- v4.12-rc3/mm/hugetlb.c +++ v4.12-rc3_patched/mm/hugetlb.c @@ -1443,7 +1443,7 @@ static int free_pool_huge_page(struct hstate *h, nodemask_t *nodes_allowed, * number of free hugepages would be reduced below the number of reserved * hugepages. */ -static int dissolve_free_huge_page(struct page *page) +int dissolve_free_huge_page(struct page *page) { int rc = 0; @@ -1456,6 +1456,14 @@ static int dissolve_free_huge_page(struct page *page) rc = -EBUSY; goto out; } + /* + * Move PageHWPoison flag from head page to the raw error page, + * which makes any subpages rather than the error page reusable. + */ + if (PageHWPoison(head) && page != head) { + SetPageHWPoison(page); + ClearPageHWPoison(head); + } list_del(&head->lru); h->free_huge_pages--; h->free_huge_pages_node[nid]--; diff --git v4.12-rc3/mm/memory-failure.c v4.12-rc3_patched/mm/memory-failure.c index aae620f..e03903f 100644 --- v4.12-rc3/mm/memory-failure.c +++ v4.12-rc3_patched/mm/memory-failure.c @@ -1571,11 +1571,8 @@ static int soft_offline_huge_page(struct page *page, int flags) if (ret > 0) ret = -EIO; } else { - /* overcommit hugetlb page will be freed to buddy */ - SetPageHWPoison(page); if (PageHuge(page)) - dequeue_hwpoisoned_huge_page(hpage); - num_poisoned_pages_inc(); + dissolve_free_huge_page(page); } return ret; } diff --git v4.12-rc3/mm/migrate.c v4.12-rc3_patched/mm/migrate.c index 89a0a17..f0319db 100644 --- v4.12-rc3/mm/migrate.c +++ v4.12-rc3_patched/mm/migrate.c @@ -1251,6 +1251,8 @@ static int unmap_and_move_huge_page(new_page_t get_new_page, out: if (rc != -EAGAIN) putback_active_hugepage(hpage); + if (reason == MR_MEMORY_FAILURE && !test_set_page_hwpoison(hpage)) + num_poisoned_pages_inc(); /* * If migration was not successful and there's a freeing callback, use -- 2.7.0
