Commit e1d8c966 authored by Miaohe Lin's avatar Miaohe Lin Committed by Linus Torvalds
Browse files

mm/page_isolation: fix potential missing call to unset_migratetype_isolate() 

In start_isolate_page_range() undo path, pfn_to_online_page() just
checks the first pfn in a pageblock while __first_valid_page() will
traverse the pageblock until the first online pfn is found.  So we may
miss the call to unset_migratetype_isolate() in undo path and pages will
remain isolated unexpectedly.

Fix this by calling undo_isolate_page_range() and this will also help to
simplify the code further.  Note we shouldn't ever trigger it because
MAX_ORDER-1 aligned pfn ranges shouldn't contain memory holes now.

Link: https://lkml.kernel.org/r/20210914114348.15569-1-linmiaohe@huawei.com


Fixes: 2ce13640 ("mm: __first_valid_page skip over offline pages")
Signed-off-by: default avatarMiaohe Lin <linmiaohe@huawei.com>
Reviewed-by: default avatarDavid Hildenbrand <david@redhat.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent ad0ce23e

mm/page_isolation.c

+3 −17
Original line number Diff line number Diff line
@@ -183,7 +183,6 @@ int start_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn, 
			     unsigned migratetype, int flags)

{

	unsigned long pfn;

	unsigned long undo_pfn;

	struct page *page;



	BUG_ON(!IS_ALIGNED(start_pfn, pageblock_nr_pages));
@@ -193,25 +192,12 @@ int start_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn, 
	     pfn < end_pfn;

	     pfn += pageblock_nr_pages) {

		page = __first_valid_page(pfn, pageblock_nr_pages);

		if (page) {

			if (set_migratetype_isolate(page, migratetype, flags)) {

				undo_pfn = pfn;

				goto undo;

			}

		if (page && set_migratetype_isolate(page, migratetype, flags)) {

			undo_isolate_page_range(start_pfn, pfn, migratetype);

			return -EBUSY;

		}

	}

	return 0;

undo:

	for (pfn = start_pfn;

	     pfn < undo_pfn;

	     pfn += pageblock_nr_pages) {

		struct page *page = pfn_to_online_page(pfn);

		if (!page)

			continue;

		unset_migratetype_isolate(page, migratetype);

	}



	return -EBUSY;

}



/*