From: Anshuman Khandual <khandual@xxxxxxxxxxxxxxxxxx>
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 <khandual@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
---
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
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