From 8d1e24c0b82d9730d05ee85eb7f4195df8cdf6a6 Mon Sep 17 00:00:00 2001 From: "Matthew Wilcox (Oracle)" Date: Wed, 3 Apr 2024 18:18:35 +0100 Subject: khugepaged: use a folio throughout collapse_file() Pull folios from the page cache instead of pages. Half of this work had been done already, but we were still operating on pages for a large chunk of this function. There is no attempt in this patch to handle large folios that are smaller than a THP; that will have to wait for a future patch. [willy@infradead.org: the unlikely() is embedded in IS_ERR()] Link: https://lkml.kernel.org/r/ZhIWX8K0E2tSyMSr@casper.infradead.org Link: https://lkml.kernel.org/r/20240403171838.1445826-7-willy@infradead.org Signed-off-by: Matthew Wilcox (Oracle) Signed-off-by: Andrew Morton --- mm/khugepaged.c | 113 +++++++++++++++++++++++++++----------------------------- 1 file changed, 54 insertions(+), 59 deletions(-) (limited to 'mm/khugepaged.c') diff --git a/mm/khugepaged.c b/mm/khugepaged.c index d44584b5e004..f3116eba4dfd 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -1780,9 +1780,8 @@ static int collapse_file(struct mm_struct *mm, unsigned long addr, struct collapse_control *cc) { struct address_space *mapping = file->f_mapping; - struct page *page; - struct page *tmp, *dst; - struct folio *folio, *new_folio; + struct page *dst; + struct folio *folio, *tmp, *new_folio; pgoff_t index = 0, end = start + HPAGE_PMD_NR; LIST_HEAD(pagelist); XA_STATE_ORDER(xas, &mapping->i_pages, start, HPAGE_PMD_ORDER); @@ -1820,11 +1819,11 @@ static int collapse_file(struct mm_struct *mm, unsigned long addr, for (index = start; index < end; index++) { xas_set(&xas, index); - page = xas_load(&xas); + folio = xas_load(&xas); VM_BUG_ON(index != xas.xa_index); if (is_shmem) { - if (!page) { + if (!folio) { /* * Stop if extent has been truncated or * hole-punched, and is now completely @@ -1840,7 +1839,7 @@ static int collapse_file(struct mm_struct *mm, unsigned long addr, continue; } - if (xa_is_value(page) || !PageUptodate(page)) { + if (xa_is_value(folio) || !folio_test_uptodate(folio)) { xas_unlock_irq(&xas); /* swap in or instantiate fallocated page */ if (shmem_get_folio(mapping->host, index, @@ -1850,28 +1849,27 @@ static int collapse_file(struct mm_struct *mm, unsigned long addr, } /* drain lru cache to help isolate_lru_page() */ lru_add_drain(); - page = folio_file_page(folio, index); - } else if (trylock_page(page)) { - get_page(page); + } else if (folio_trylock(folio)) { + folio_get(folio); xas_unlock_irq(&xas); } else { result = SCAN_PAGE_LOCK; goto xa_locked; } } else { /* !is_shmem */ - if (!page || xa_is_value(page)) { + if (!folio || xa_is_value(folio)) { xas_unlock_irq(&xas); page_cache_sync_readahead(mapping, &file->f_ra, file, index, end - index); /* drain lru cache to help isolate_lru_page() */ lru_add_drain(); - page = find_lock_page(mapping, index); - if (unlikely(page == NULL)) { + folio = filemap_lock_folio(mapping, index); + if (IS_ERR(folio)) { result = SCAN_FAIL; goto xa_unlocked; } - } else if (PageDirty(page)) { + } else if (folio_test_dirty(folio)) { /* * khugepaged only works on read-only fd, * so this page is dirty because it hasn't @@ -1889,12 +1887,12 @@ static int collapse_file(struct mm_struct *mm, unsigned long addr, filemap_flush(mapping); result = SCAN_FAIL; goto xa_unlocked; - } else if (PageWriteback(page)) { + } else if (folio_test_writeback(folio)) { xas_unlock_irq(&xas); result = SCAN_FAIL; goto xa_unlocked; - } else if (trylock_page(page)) { - get_page(page); + } else if (folio_trylock(folio)) { + folio_get(folio); xas_unlock_irq(&xas); } else { result = SCAN_PAGE_LOCK; @@ -1903,35 +1901,31 @@ static int collapse_file(struct mm_struct *mm, unsigned long addr, } /* - * The page must be locked, so we can drop the i_pages lock + * The folio must be locked, so we can drop the i_pages lock * without racing with truncate. */ - VM_BUG_ON_PAGE(!PageLocked(page), page); + VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio); - /* make sure the page is up to date */ - if (unlikely(!PageUptodate(page))) { + /* make sure the folio is up to date */ + if (unlikely(!folio_test_uptodate(folio))) { result = SCAN_FAIL; goto out_unlock; } /* * If file was truncated then extended, or hole-punched, before - * we locked the first page, then a THP might be there already. + * we locked the first folio, then a THP might be there already. * This will be discovered on the first iteration. */ - if (PageTransCompound(page)) { - struct page *head = compound_head(page); - - result = compound_order(head) == HPAGE_PMD_ORDER && - head->index == start + if (folio_test_large(folio)) { + result = folio_order(folio) == HPAGE_PMD_ORDER && + folio->index == start /* Maybe PMD-mapped */ ? SCAN_PTE_MAPPED_HUGEPAGE : SCAN_PAGE_COMPOUND; goto out_unlock; } - folio = page_folio(page); - if (folio_mapping(folio) != mapping) { result = SCAN_TRUNCATED; goto out_unlock; @@ -1941,7 +1935,7 @@ static int collapse_file(struct mm_struct *mm, unsigned long addr, folio_test_writeback(folio))) { /* * khugepaged only works on read-only fd, so this - * page is dirty because it hasn't been flushed + * folio is dirty because it hasn't been flushed * since first write. */ result = SCAN_FAIL; @@ -1965,33 +1959,34 @@ static int collapse_file(struct mm_struct *mm, unsigned long addr, xas_lock_irq(&xas); - VM_BUG_ON_PAGE(page != xa_load(xas.xa, index), page); + VM_BUG_ON_FOLIO(folio != xa_load(xas.xa, index), folio); /* - * We control three references to the page: + * We control three references to the folio: * - we hold a pin on it; * - one reference from page cache; - * - one from isolate_lru_page; - * If those are the only references, then any new usage of the - * page will have to fetch it from the page cache. That requires - * locking the page to handle truncate, so any new usage will be - * blocked until we unlock page after collapse/during rollback. + * - one from lru_isolate_folio; + * If those are the only references, then any new usage + * of the folio will have to fetch it from the page + * cache. That requires locking the folio to handle + * truncate, so any new usage will be blocked until we + * unlock folio after collapse/during rollback. */ - if (page_count(page) != 3) { + if (folio_ref_count(folio) != 3) { result = SCAN_PAGE_COUNT; xas_unlock_irq(&xas); - putback_lru_page(page); + folio_putback_lru(folio); goto out_unlock; } /* - * Accumulate the pages that are being collapsed. + * Accumulate the folios that are being collapsed. */ - list_add_tail(&page->lru, &pagelist); + list_add_tail(&folio->lru, &pagelist); continue; out_unlock: - unlock_page(page); - put_page(page); + folio_unlock(folio); + folio_put(folio); goto xa_unlocked; } @@ -2030,17 +2025,17 @@ xa_unlocked: } /* - * The old pages are locked, so they won't change anymore. + * The old folios are locked, so they won't change anymore. */ index = start; dst = folio_page(new_folio, 0); - list_for_each_entry(page, &pagelist, lru) { - while (index < page->index) { + list_for_each_entry(folio, &pagelist, lru) { + while (index < folio->index) { clear_highpage(dst); index++; dst++; } - if (copy_mc_highpage(dst, page) > 0) { + if (copy_mc_highpage(dst, folio_page(folio, 0)) > 0) { result = SCAN_COPY_MC; goto rollback; } @@ -2152,15 +2147,15 @@ immap_locked: folio_unlock(new_folio); /* - * The collapse has succeeded, so free the old pages. + * The collapse has succeeded, so free the old folios. */ - list_for_each_entry_safe(page, tmp, &pagelist, lru) { - list_del(&page->lru); - page->mapping = NULL; - ClearPageActive(page); - ClearPageUnevictable(page); - unlock_page(page); - folio_put_refs(page_folio(page), 3); + list_for_each_entry_safe(folio, tmp, &pagelist, lru) { + list_del(&folio->lru); + folio->mapping = NULL; + folio_clear_active(folio); + folio_clear_unevictable(folio); + folio_unlock(folio); + folio_put_refs(folio, 3); } goto out; @@ -2174,11 +2169,11 @@ rollback: shmem_uncharge(mapping->host, nr_none); } - list_for_each_entry_safe(page, tmp, &pagelist, lru) { - list_del(&page->lru); - unlock_page(page); - putback_lru_page(page); - put_page(page); + list_for_each_entry_safe(folio, tmp, &pagelist, lru) { + list_del(&folio->lru); + folio_unlock(folio); + folio_putback_lru(folio); + folio_put(folio); } /* * Undo the updates of filemap_nr_thps_inc for non-SHMEM -- cgit v1.2.3-58-ga151