+ vmscan-move-initialisation-of-mapping-down.patch added to mm-unstable branch

[Andrew Morton <akpm@linux-foundation.org>]

The patch titled
     Subject: vmscan: move initialisation of mapping down
has been added to the -mm mm-unstable branch.  Its filename is
     vmscan-move-initialisation-of-mapping-down.patch

This patch should soon appear in the mm-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Subject: vmscan: move initialisation of mapping down

Now that we don't interrogate the BDI for congestion, we can delay looking
up the folio's mapping until we've got further through the function,
reducing register pressure and saving a call to folio_mapping for folios
we're adding to the swap cache.

Link: https://lkml.kernel.org/r/20220504182857.4013401-13-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/vmscan.c |    7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

--- a/mm/vmscan.c~vmscan-move-initialisation-of-mapping-down
+++ a/mm/vmscan.c
@@ -1588,12 +1588,11 @@ retry:
 			stat->nr_unqueued_dirty += nr_pages;
 
 		/*
-		 * Treat this page as congested if the underlying BDI is or if
+		 * Treat this page as congested if
 		 * pages are cycling through the LRU so quickly that the
 		 * pages marked for immediate reclaim are making it to the
 		 * end of the LRU a second time.
 		 */
-		mapping = page_mapping(page);
 		if (writeback && PageReclaim(page))
 			stat->nr_congested += nr_pages;
 
@@ -1744,9 +1743,6 @@ retry:
 					if (!add_to_swap(folio))
 						goto activate_locked_split;
 				}
-
-				/* Adding to swap updated mapping */
-				mapping = page_mapping(page);
 			}
 		} else if (PageSwapBacked(page) && PageTransHuge(page)) {
 			/* Split shmem THP */
@@ -1787,6 +1783,7 @@ retry:
 			}
 		}
 
+		mapping = folio_mapping(folio);
 		if (folio_test_dirty(folio)) {
 			/*
 			 * Only kswapd can writeback filesystem folios
_

Patches currently in -mm which might be from willy@infradead.org are

shmem-convert-shmem_alloc_hugepage-to-use-vma_alloc_folio.patch
mm-huge_memory-convert-do_huge_pmd_anonymous_page-to-use-vma_alloc_folio.patch
alpha-fix-alloc_zeroed_user_highpage_movable.patch
mm-remove-alloc_pages_vma.patch
vmscan-use-folio_mapped-in-shrink_page_list.patch
vmscan-convert-the-writeback-handling-in-shrink_page_list-to-folios.patch
swap-turn-get_swap_page-into-folio_alloc_swap.patch
swap-convert-add_to_swap-to-take-a-folio.patch
vmscan-convert-dirty-page-handling-to-folios.patch
vmscan-convert-page-buffer-handling-to-use-folios.patch
vmscan-convert-lazy-freeing-to-folios.patch
vmscan-move-initialisation-of-mapping-down.patch
vmscan-convert-the-activate_locked-portion-of-shrink_page_list-to-folios.patch
mm-allow-can_split_folio-to-be-called-when-thp-are-disabled.patch
vmscan-remove-remaining-uses-of-page-in-shrink_page_list.patch
mm-shmem-use-a-folio-in-shmem_unused_huge_shrink.patch
mm-swap-add-folio_throttle_swaprate.patch
mm-shmem-convert-shmem_add_to_page_cache-to-take-a-folio.patch
mm-shmem-turn-shmem_should_replace_page-into-shmem_should_replace_folio.patch
mm-shmem-add-shmem_alloc_folio.patch
mm-shmem-convert-shmem_alloc_and_acct_page-to-use-a-folio.patch
mm-shmem-convert-shmem_getpage_gfp-to-use-a-folio.patch
mm-shmem-convert-shmem_swapin_page-to-shmem_swapin_folio.patch
mm-add-folio_mapping_flags.patch
mm-add-folio_test_movable.patch
mm-migrate-convert-move_to_new_page-into-move_to_new_folio.patch