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Commit c3114a84 authored by Anshuman Khandual's avatar Anshuman Khandual Committed by Linus Torvalds
Browse files

mm: hugetlb: soft-offline: dissolve source hugepage after successful migration 

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.

[arnd@arndb.de: fix warnings: replace some macros with inline functions]
  Link: http://lkml.kernel.org/r/20170609102544.2947326-1-arnd@arndb.de
Link: http://lkml.kernel.org/r/1496305019-5493-5-git-send-email-n-horiguchi@ah.jp.nec.com


Signed-off-by: default avatarAnshuman Khandual <khandual@linux.vnet.ibm.com>
Signed-off-by: default avatarNaoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: default avatarArnd Bergmann <arnd@arndb.de>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent b37ff71c

include/linux/hugetlb.h

+27 −4
Original line number Diff line number Diff line
@@ -472,6 +472,7 @@ 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)
@@ -550,15 +551,37 @@ static inline unsigned int pages_per_huge_page(struct hstate *h) 
{

	return 1;

}

#define hstate_index_to_shift(index) 0

#define hstate_index(h) 0



static inline unsigned hstate_index_to_shift(unsigned index)

{

	return 0;

}



static inline int hstate_index(struct hstate *h)

{

	return 0;

}



static inline pgoff_t basepage_index(struct page *page)

{

	return page->index;

}

#define dissolve_free_huge_pages(s, e)	0

#define hugepage_migration_supported(h)	false



static inline int dissolve_free_huge_page(struct page *page)

{

	return 0;

}



static inline int dissolve_free_huge_pages(unsigned long start_pfn,

					   unsigned long end_pfn)

{

	return 0;

}



static inline bool hugepage_migration_supported(struct hstate *h)

{

	return false;

}



static inline spinlock_t *huge_pte_lockptr(struct hstate *h,

					   struct mm_struct *mm, pte_t *pte)

mm/hugetlb.c

+9 −1
Original line number Diff line number Diff line
@@ -1459,7 +1459,7 @@ 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;
@@ -1472,6 +1472,14 @@ 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]--;

mm/memory-failure.c

+1 −4
Original line number Diff line number Diff line
@@ -1575,11 +1575,8 @@ 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;

}

mm/migrate.c

+2 −0
Original line number Diff line number Diff line
@@ -1252,6 +1252,8 @@ 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