Commit 7de856ff authored by Baolin Wang's avatar Baolin Wang Committed by Andrew Morton
Browse files

mm: khugepaged: support shmem mTHP collapse 

Shmem already supports the allocation of mTHP, but khugepaged does not yet
support collapsing mTHP folios.  Now khugepaged is ready to support mTHP,
and this patch enables the collapse of shmem mTHP.

Link: https://lkml.kernel.org/r/b9da76aab4276eb6e5d12c479af2b5eea5b4575d.1724140601.git.baolin.wang@linux.alibaba.com


Signed-off-by: default avatarBaolin Wang <baolin.wang@linux.alibaba.com>
Cc: Barry Song <21cnbao@gmail.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent dfa98f56

mm/khugepaged.c

+11 −17
Original line number Diff line number Diff line
@@ -1843,7 +1843,7 @@ static int collapse_file(struct mm_struct *mm, unsigned long addr, 
		}

	} while (1);



	for (index = start; index < end; index++) {

	for (index = start; index < end;) {

		xas_set(&xas, index);

		folio = xas_load(&xas);
@@ -1862,6 +1862,7 @@ static int collapse_file(struct mm_struct *mm, unsigned long addr, 
					}

				}

				nr_none++;

				index++;

				continue;

			}
@@ -1943,12 +1944,10 @@ static int collapse_file(struct mm_struct *mm, unsigned long addr, 
		 * we locked the first folio, then a THP might be there already.

		 * This will be discovered on the first iteration.

		 */

		if (folio_test_large(folio)) {

			result = folio_order(folio) == HPAGE_PMD_ORDER &&

					folio->index == start

		if (folio_order(folio) == HPAGE_PMD_ORDER &&

		    folio->index == start) {

			/* Maybe PMD-mapped */

					? SCAN_PTE_MAPPED_HUGEPAGE

					: SCAN_PAGE_COMPOUND;

			result = SCAN_PTE_MAPPED_HUGEPAGE;

			goto out_unlock;

		}
@@ -2009,6 +2008,7 @@ static int collapse_file(struct mm_struct *mm, unsigned long addr, 
		 * Accumulate the folios that are being collapsed.

		 */

		list_add_tail(&folio->lru, &pagelist);

		index += folio_nr_pages(folio);

		continue;

out_unlock:

		folio_unlock(folio);
@@ -2261,16 +2261,10 @@ static int hpage_collapse_scan_file(struct mm_struct *mm, unsigned long addr, 
			continue;

		}



		/*

		 * TODO: khugepaged should compact smaller compound pages

		 * into a PMD sized page

		 */

		if (folio_test_large(folio)) {

			result = folio_order(folio) == HPAGE_PMD_ORDER &&

					folio->index == start

		if (folio_order(folio) == HPAGE_PMD_ORDER &&

		    folio->index == start) {

			/* Maybe PMD-mapped */

					? SCAN_PTE_MAPPED_HUGEPAGE

					: SCAN_PAGE_COMPOUND;

			result = SCAN_PTE_MAPPED_HUGEPAGE;

			/*

			 * For SCAN_PTE_MAPPED_HUGEPAGE, further processing

			 * by the caller won't touch the page cache, and so