The patch titled
Subject: mm: add free_unref_folios()
has been added to the -mm mm-unstable branch. Its filename is
mm-add-free_unref_folios.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-add-free_unref_folios.patch
This patch will later 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@xxxxxxxxxxxxx>
Subject: mm: add free_unref_folios()
Date: Tue, 27 Feb 2024 17:42:37 +0000
Iterate over a folio_batch rather than a linked list. This is easier for
the CPU to prefetch and has a batch count naturally built in so we don't
need to track it. Again, this lowers the maximum lock hold time from
32 folios to 15, but I do not expect this to have a significant effect.
Link: https://lkml.kernel.org/r/20240227174254.710559-4-willy@xxxxxxxxxxxxx
Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxx>
Cc: Ryan Roberts <ryan.roberts@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/internal.h | 5 ++-
mm/page_alloc.c | 59 ++++++++++++++++++++++++++++------------------
2 files changed, 39 insertions(+), 25 deletions(-)
--- a/mm/internal.h~mm-add-free_unref_folios
+++ a/mm/internal.h
@@ -541,8 +541,9 @@ extern bool free_pages_prepare(struct pa
extern int user_min_free_kbytes;
-extern void free_unref_page(struct page *page, unsigned int order);
-extern void free_unref_page_list(struct list_head *list);
+void free_unref_page(struct page *page, unsigned int order);
+void free_unref_folios(struct folio_batch *fbatch);
+void free_unref_page_list(struct list_head *list);
extern void zone_pcp_reset(struct zone *zone);
extern void zone_pcp_disable(struct zone *zone);
--- a/mm/page_alloc.c~mm-add-free_unref_folios
+++ a/mm/page_alloc.c
@@ -32,6 +32,7 @@
#include <linux/sysctl.h>
#include <linux/cpu.h>
#include <linux/cpuset.h>
+#include <linux/pagevec.h>
#include <linux/memory_hotplug.h>
#include <linux/nodemask.h>
#include <linux/vmstat.h>
@@ -2515,57 +2516,51 @@ void free_unref_page(struct page *page,
}
/*
- * Free a list of 0-order pages
+ * Free a batch of 0-order pages
*/
-void free_unref_page_list(struct list_head *list)
+void free_unref_folios(struct folio_batch *folios)
{
unsigned long __maybe_unused UP_flags;
- struct folio *folio, *next;
struct per_cpu_pages *pcp = NULL;
struct zone *locked_zone = NULL;
- int batch_count = 0;
- int migratetype;
+ int i, j, migratetype;
- /* Prepare pages for freeing */
- list_for_each_entry_safe(folio, next, list, lru) {
+ /* Prepare folios for freeing */
+ for (i = 0, j = 0; i < folios->nr; i++) {
+ struct folio *folio = folios->folios[i];
unsigned long pfn = folio_pfn(folio);
- if (!free_unref_page_prepare(&folio->page, pfn, 0)) {
- list_del(&folio->lru);
+ if (!free_unref_page_prepare(&folio->page, pfn, 0))
continue;
- }
/*
- * Free isolated pages directly to the allocator, see
+ * Free isolated folios directly to the allocator, see
* comment in free_unref_page.
*/
migratetype = get_pcppage_migratetype(&folio->page);
if (unlikely(is_migrate_isolate(migratetype))) {
- list_del(&folio->lru);
free_one_page(folio_zone(folio), &folio->page, pfn,
0, migratetype, FPI_NONE);
continue;
}
+ if (j != i)
+ folios->folios[j] = folio;
+ j++;
}
+ folios->nr = j;
- list_for_each_entry_safe(folio, next, list, lru) {
+ for (i = 0; i < folios->nr; i++) {
+ struct folio *folio = folios->folios[i];
struct zone *zone = folio_zone(folio);
- list_del(&folio->lru);
migratetype = get_pcppage_migratetype(&folio->page);
- /*
- * Either different zone requiring a different pcp lock or
- * excessive lock hold times when freeing a large list of
- * folios.
- */
- if (zone != locked_zone || batch_count == SWAP_CLUSTER_MAX) {
+ /* Different zone requires a different pcp lock */
+ if (zone != locked_zone) {
if (pcp) {
pcp_spin_unlock(pcp);
pcp_trylock_finish(UP_flags);
}
- batch_count = 0;
-
/*
* trylock is necessary as folios may be getting freed
* from IRQ or SoftIRQ context after an IO completion.
@@ -2592,13 +2587,31 @@ void free_unref_page_list(struct list_he
trace_mm_page_free_batched(&folio->page);
free_unref_page_commit(zone, pcp, &folio->page, migratetype, 0);
- batch_count++;
}
if (pcp) {
pcp_spin_unlock(pcp);
pcp_trylock_finish(UP_flags);
}
+ folio_batch_reinit(folios);
+}
+
+void free_unref_page_list(struct list_head *list)
+{
+ struct folio_batch fbatch;
+
+ folio_batch_init(&fbatch);
+ while (!list_empty(list)) {
+ struct folio *folio = list_first_entry(list, struct folio, lru);
+
+ list_del(&folio->lru);
+ if (folio_batch_add(&fbatch, folio) > 0)
+ continue;
+ free_unref_folios(&fbatch);
+ }
+
+ if (fbatch.nr)
+ free_unref_folios(&fbatch);
}
/*
_
Patches currently in -mm which might be from willy@xxxxxxxxxxxxx are
mm-support-order-1-folios-in-the-page-cache.patch
mm-make-folios_put-the-basis-of-release_pages.patch
mm-convert-free_unref_page_list-to-use-folios.patch
mm-add-free_unref_folios.patch
mm-use-folios_put-in-__folio_batch_release.patch
memcg-add-mem_cgroup_uncharge_folios.patch
mm-remove-use-of-folio-list-from-folios_put.patch
mm-use-free_unref_folios-in-put_pages_list.patch
mm-use-__page_cache_release-in-folios_put.patch
mm-handle-large-folios-in-free_unref_folios.patch
mm-allow-non-hugetlb-large-folios-to-be-batch-processed.patch
mm-free-folios-in-a-batch-in-shrink_folio_list.patch
mm-free-folios-directly-in-move_folios_to_lru.patch
memcg-remove-mem_cgroup_uncharge_list.patch
mm-remove-free_unref_page_list.patch
mm-remove-lru_to_page.patch
mm-convert-free_pages_and_swap_cache-to-use-folios_put.patch
mm-use-a-folio-in-__collapse_huge_page_copy_succeeded.patch
mm-convert-free_swap_cache-to-take-a-folio.patch
