Commit 6c74828f authored by Baolin Wang's avatar Baolin Wang Committed by Nanyong Sun
Browse files

mm: khugepaged: support shmem mTHP collapse 

mainline inclusion
from mainline-v6.12-rc1
commit 7de856ffd007f132fd4a0474b289a622a3f88cd7
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/IAXCD2

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=7de856ffd007f132fd4a0474b289a622a3f88cd7

--------------------------------

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>
Signed-off-by: default avatarNanyong Sun <sunnanyong@huawei.com>
parent 72c1584c

mm/khugepaged.c

+11 −17
Original line number Diff line number Diff line
@@ -1857,7 +1857,7 @@ 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);
@@ -1876,6 +1876,7 @@ static int collapse_file(struct mm_struct *mm, unsigned long addr, 
					}

				}

				nr_none++;

				index++;

				continue;

			}
@@ -1957,12 +1958,10 @@ 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;

		}
@@ -2023,6 +2022,7 @@ 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);
@@ -2276,16 +2276,10 @@ 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