Commit 0a36111c authored by Matthew Wilcox (Oracle)'s avatar Matthew Wilcox (Oracle) Committed by Andrew Morton
Browse files

vmscan: convert page buffer handling to use folios 

This mostly just removes calls to compound_head() although nr_reclaimed
should be incremented by the number of pages, not just 1.

Link: https://lkml.kernel.org/r/20220504182857.4013401-11-willy@infradead.org


Signed-off-by: default avatarMatthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 49bd2bf9

mm/vmscan.c

+25 −23
Original line number Diff line number Diff line
@@ -1859,38 +1859,40 @@ static unsigned int shrink_page_list(struct list_head *page_list, 
		}



		/*

		 * If the page has buffers, try to free the buffer mappings

		 * associated with this page. If we succeed we try to free

		 * the page as well.

		 * If the folio has buffers, try to free the buffer

		 * mappings associated with this folio. If we succeed

		 * we try to free the folio as well.

		 *

		 * We do this even if the page is PageDirty().

		 * try_to_release_page() does not perform I/O, but it is

		 * possible for a page to have PageDirty set, but it is actually

		 * clean (all its buffers are clean).  This happens if the

		 * buffers were written out directly, with submit_bh(). ext3

		 * will do this, as well as the blockdev mapping.

		 * try_to_release_page() will discover that cleanness and will

		 * drop the buffers and mark the page clean - it can be freed.

		 * We do this even if the folio is dirty.

		 * filemap_release_folio() does not perform I/O, but it

		 * is possible for a folio to have the dirty flag set,

		 * but it is actually clean (all its buffers are clean).

		 * This happens if the buffers were written out directly,

		 * with submit_bh(). ext3 will do this, as well as

		 * the blockdev mapping.  filemap_release_folio() will

		 * discover that cleanness and will drop the buffers

		 * and mark the folio clean - it can be freed.

		 *

		 * Rarely, pages can have buffers and no ->mapping.  These are

		 * the pages which were not successfully invalidated in

		 * truncate_cleanup_page().  We try to drop those buffers here

		 * and if that worked, and the page is no longer mapped into

		 * process address space (page_count == 1) it can be freed.

		 * Otherwise, leave the page on the LRU so it is swappable.

		 */

		if (page_has_private(page)) {

			if (!try_to_release_page(page, sc->gfp_mask))

		 * Rarely, folios can have buffers and no ->mapping.

		 * These are the folios which were not successfully

		 * invalidated in truncate_cleanup_folio().  We try to

		 * drop those buffers here and if that worked, and the

		 * folio is no longer mapped into process address space

		 * (refcount == 1) it can be freed.  Otherwise, leave

		 * the folio on the LRU so it is swappable.

		 */

		if (folio_has_private(folio)) {

			if (!filemap_release_folio(folio, sc->gfp_mask))

				goto activate_locked;

			if (!mapping && page_count(page) == 1) {

				unlock_page(page);

				if (put_page_testzero(page))

			if (!mapping && folio_ref_count(folio) == 1) {

				folio_unlock(folio);

				if (folio_put_testzero(folio))

					goto free_it;

				else {

					/*

					 * rare race with speculative reference.

					 * the speculative reference will free

					 * this page shortly, so we may

					 * this folio shortly, so we may

					 * increment nr_reclaimed here (and

					 * leave it off the LRU).

					 */