Commit 6c141973 authored by Mike Kravetz's avatar Mike Kravetz Committed by Andrew Morton
Browse files

hugetlb: clear flags in tail pages that will be freed individually 

hugetlb manually creates and destroys compound pages.  As such it makes
assumptions about struct page layout.  Commit ebc1baf5 ("mm: free up a
word in the first tail page") breaks hugetlb.  The following will fix the
breakage.

Link: https://lkml.kernel.org/r/20230822231741.GC4509@monkey


Fixes: ebc1baf5 ("mm: free up a word in the first tail page")
Signed-off-by: default avatarMike Kravetz <mike.kravetz@oracle.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent fcbc329f

mm/hugetlb.c

+1 −10
Original line number Diff line number Diff line
@@ -1484,6 +1484,7 @@ static void __destroy_compound_gigantic_folio(struct folio *folio, 


	for (i = 1; i < nr_pages; i++) {

		p = folio_page(folio, i);

		p->flags &= ~PAGE_FLAGS_CHECK_AT_FREE;

		p->mapping = NULL;

		clear_compound_head(p);

		if (!demote)
@@ -1702,8 +1703,6 @@ static void add_hugetlb_folio(struct hstate *h, struct folio *folio, 
static void __update_and_free_hugetlb_folio(struct hstate *h,

						struct folio *folio)

{

	int i;

	struct page *subpage;

	bool clear_dtor = folio_test_hugetlb_vmemmap_optimized(folio);



	if (hstate_is_gigantic(h) && !gigantic_page_runtime_supported())
@@ -1745,14 +1744,6 @@ static void __update_and_free_hugetlb_folio(struct hstate *h, 
		spin_unlock_irq(&hugetlb_lock);

	}



	for (i = 0; i < pages_per_huge_page(h); i++) {

		subpage = folio_page(folio, i);

		subpage->flags &= ~(1 << PG_locked | 1 << PG_error |

				1 << PG_referenced | 1 << PG_dirty |

				1 << PG_active | 1 << PG_private |

				1 << PG_writeback);

	}



	/*

	 * Non-gigantic pages demoted from CMA allocated gigantic pages

	 * need to be given back to CMA in free_gigantic_folio.