Commit 835fe6a4 authored by Zi Yan's avatar Zi Yan Committed by Liu Shixin
Browse files

mm/compaction: optimize >0 order folio compaction with free page split. 

mainline inclusion
from mainline-v6.9-rc1
commit 73318e2cafe53e8b7c8899d990cf8eaca32184d0
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I9CXS6
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=73318e2cafe53e8b7c8899d990cf8eaca32184d0

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

During migration in a memory compaction, free pages are placed in an array
of page lists based on their order.  But the desired free page order
(i.e., the order of a source page) might not be always present, thus
leading to migration failures and premature compaction termination.  Split
a high order free pages when source migration page has a lower order to
increase migration successful rate.

Note: merging free pages when a migration fails and a lower order free
page is returned via compaction_free() is possible, but there is too much
work.  Since the free pages are not buddy pages, it is hard to identify
these free pages using existing PFN-based page merging algorithm.

Link: https://lkml.kernel.org/r/20240220183220.1451315-5-zi.yan@sent.com


Signed-off-by: default avatarZi Yan <ziy@nvidia.com>
Reviewed-by: default avatarBaolin Wang <baolin.wang@linux.alibaba.com>
Reviewed-by: default avatarVlastimil Babka <vbabka@suse.cz>
Tested-by: default avatarBaolin Wang <baolin.wang@linux.alibaba.com>
Tested-by: default avatarYu Zhao <yuzhao@google.com>
Cc: Adam Manzanares <a.manzanares@samsung.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Huang Ying <ying.huang@intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kemeng Shi <shikemeng@huaweicloud.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Luis Chamberlain <mcgrof@kernel.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Yin Fengwei <fengwei.yin@intel.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLiu Shixin <liushixin2@huawei.com>
parent 0fc4fa55

mm/compaction.c

+30 −5
Original line number Diff line number Diff line
@@ -1838,15 +1838,40 @@ static struct folio *compaction_alloc(struct folio *src, unsigned long data) 
	struct compact_control *cc = (struct compact_control *)data;

	struct folio *dst;

	int order = folio_order(src);

	bool has_isolated_pages = false;

	int start_order;

	struct page *freepage;

	unsigned long size;



	if (list_empty(&cc->freepages[order])) {

		isolate_freepages(cc);

		if (list_empty(&cc->freepages[order]))

again:

	for (start_order = order; start_order < NR_PAGE_ORDERS; start_order++)

		if (!list_empty(&cc->freepages[start_order]))

			break;



	/* no free pages in the list */

	if (start_order == NR_PAGE_ORDERS) {

		if (has_isolated_pages)

			return NULL;

		isolate_freepages(cc);

		has_isolated_pages = true;

		goto again;

	}



	freepage = list_first_entry(&cc->freepages[start_order], struct page,

				lru);

	size = 1 << start_order;



	list_del(&freepage->lru);



	while (start_order > order) {

		start_order--;

		size >>= 1;



		list_add(&freepage[size].lru, &cc->freepages[start_order]);

		set_page_private(&freepage[size], start_order);

	}

	dst = (struct folio *)freepage;



	dst = list_first_entry(&cc->freepages[order], struct folio, lru);

	list_del(&dst->lru);

	post_alloc_hook(&dst->page, order, __GFP_MOVABLE);

	if (order)

		prep_compound_page(&dst->page, order);