The quilt patch titled
Subject: mm/page_alloc: simplify locking during free_unref_page_list
has been removed from the -mm tree. Its filename was
mm-page_alloc-simplify-locking-during-free_unref_page_list.patch
This patch was dropped because it was merged into the mm-stable branch
of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
------------------------------------------------------
From: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
Subject: mm/page_alloc: simplify locking during free_unref_page_list
Date: Tue, 22 Nov 2022 13:12:29 +0000
While freeing a large list, the zone lock will be released and reacquired
to avoid long hold times since commit c24ad77d962c ("mm/page_alloc.c:
avoid excessive IRQ disabled times in free_unref_page_list()"). As
suggested by Vlastimil Babka, the lockrelease/reacquire logic can be
simplified by reusing the logic that acquires a different lock when
changing zones.
Link: https://lkml.kernel.org/r/20221122131229.5263-3-mgorman@xxxxxxxxxxxxxxxxxxx
Signed-off-by: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
Reviewed-by: Vlastimil Babka <vbabka@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/page_alloc.c | 25 +++++++++----------------
1 file changed, 9 insertions(+), 16 deletions(-)
--- a/mm/page_alloc.c~mm-page_alloc-simplify-locking-during-free_unref_page_list
+++ a/mm/page_alloc.c
@@ -3525,13 +3525,19 @@ void free_unref_page_list(struct list_he
list_del(&page->lru);
migratetype = get_pcppage_migratetype(page);
- /* Different zone, different pcp lock. */
- if (zone != locked_zone) {
+ /*
+ * Either different zone requiring a different pcp lock or
+ * excessive lock hold times when freeing a large list of
+ * pages.
+ */
+ if (zone != locked_zone || batch_count == SWAP_CLUSTER_MAX) {
if (pcp) {
pcp_spin_unlock(pcp);
pcp_trylock_finish(UP_flags);
}
+ batch_count = 0;
+
/*
* trylock is necessary as pages may be getting freed
* from IRQ or SoftIRQ context after an IO completion.
@@ -3546,7 +3552,6 @@ void free_unref_page_list(struct list_he
continue;
}
locked_zone = zone;
- batch_count = 0;
}
/*
@@ -3558,19 +3563,7 @@ void free_unref_page_list(struct list_he
trace_mm_page_free_batched(page);
free_unref_page_commit(zone, pcp, page, migratetype, 0);
-
- /*
- * Guard against excessive lock hold times when freeing
- * a large list of pages. Lock will be reacquired if
- * necessary on the next iteration.
- */
- if (++batch_count == SWAP_CLUSTER_MAX) {
- pcp_spin_unlock(pcp);
- pcp_trylock_finish(UP_flags);
- batch_count = 0;
- pcp = NULL;
- locked_zone = NULL;
- }
+ batch_count++;
}
if (pcp) {
_
Patches currently in -mm which might be from mgorman@xxxxxxxxxxxxxxxxxxx are
