From: "Kirill A. Shutemov" <kirill@xxxxxxxxxxxxx> Subject: mm/huge_memory: fix split assumption of page size File THPs may now be of arbitrary size, and we can't rely on that size after doing the split so remember the number of pages before we start the split. Link: https://lkml.kernel.org/r/20200908195539.25896-6-willy@xxxxxxxxxxxxx Signed-off-by: Kirill A. Shutemov <kirill@xxxxxxxxxxxxx> Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx> Reviewed-by: SeongJae Park <sjpark@xxxxxxxxx> Cc: Huang Ying <ying.huang@xxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/huge_memory.c | 15 ++++++++------- 1 file changed, 8 insertions(+), 7 deletions(-) --- a/mm/huge_memory.c~mm-huge_memory-fix-split-assumption-of-page-size +++ a/mm/huge_memory.c @@ -2335,13 +2335,13 @@ static void unmap_page(struct page *page VM_BUG_ON_PAGE(!unmap_success, page); } -static void remap_page(struct page *page) +static void remap_page(struct page *page, unsigned int nr) { int i; if (PageTransHuge(page)) { remove_migration_ptes(page, page, true); } else { - for (i = 0; i < HPAGE_PMD_NR; i++) + for (i = 0; i < nr; i++) remove_migration_ptes(page + i, page + i, true); } } @@ -2419,6 +2419,7 @@ static void __split_huge_page(struct pag struct lruvec *lruvec; struct address_space *swap_cache = NULL; unsigned long offset = 0; + unsigned int nr = thp_nr_pages(head); int i; lruvec = mem_cgroup_page_lruvec(head, pgdat); @@ -2434,7 +2435,7 @@ static void __split_huge_page(struct pag xa_lock(&swap_cache->i_pages); } - for (i = HPAGE_PMD_NR - 1; i >= 1; i--) { + for (i = nr - 1; i >= 1; i--) { __split_huge_page_tail(head, i, lruvec, list); /* Some pages can be beyond i_size: drop them from page cache */ if (head[i].index >= end) { @@ -2454,7 +2455,7 @@ static void __split_huge_page(struct pag ClearPageCompound(head); - split_page_owner(head, HPAGE_PMD_NR); + split_page_owner(head, nr); /* See comment in __split_huge_page_tail() */ if (PageAnon(head)) { @@ -2473,9 +2474,9 @@ static void __split_huge_page(struct pag spin_unlock_irqrestore(&pgdat->lru_lock, flags); - remap_page(head); + remap_page(head, nr); - for (i = 0; i < HPAGE_PMD_NR; i++) { + for (i = 0; i < nr; i++) { struct page *subpage = head + i; if (subpage == page) continue; @@ -2729,7 +2730,7 @@ int split_huge_page_to_list(struct page fail: if (mapping) xa_unlock(&mapping->i_pages); spin_unlock_irqrestore(&pgdata->lru_lock, flags); - remap_page(head); + remap_page(head, thp_nr_pages(head)); ret = -EBUSY; } _
