From: Zi Yan <zi.yan@sent.com>
To: linux-mm@kvack.org
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
Steven Rostedt <rostedt@goodmis.org>,
David Hildenbrand <david@redhat.com>,
Vlastimil Babka <vbabka@suse.cz>,
Mel Gorman <mgorman@techsingularity.net>,
Mike Rapoport <rppt@kernel.org>,
Oscar Salvador <osalvador@suse.de>,
Andrew Morton <akpm@linux-foundation.org>,
linux-kernel@vger.kernel.org, Zi Yan <ziy@nvidia.com>
Subject: [PATCH v2 1/2] mm: page_alloc: simplify pageblock migratetype check in __free_one_page().
Date: Fri, 1 Apr 2022 14:11:08 -0400 [thread overview]
Message-ID: <20220401181109.1477354-1-zi.yan@sent.com> (raw)
From: Zi Yan <ziy@nvidia.com>
Move pageblock migratetype check code in the while loop to simplify the
logic. It also saves redundant buddy page checking code.
Suggested-by: Vlastimil Babka <vbabka@suse.cz>
Link: https://lore.kernel.org/linux-mm/27ff69f9-60c5-9e59-feb2-295250077551@suse.cz/
Signed-off-by: Zi Yan <ziy@nvidia.com>
---
mm/page_alloc.c | 46 +++++++++++++++++-----------------------------
1 file changed, 17 insertions(+), 29 deletions(-)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 856473e54155..2ea106146686 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1054,7 +1054,6 @@ static inline void __free_one_page(struct page *page,
int migratetype, fpi_t fpi_flags)
{
struct capture_control *capc = task_capc(zone);
- unsigned int max_order = pageblock_order;
unsigned long buddy_pfn;
unsigned long combined_pfn;
struct page *buddy;
@@ -1070,8 +1069,7 @@ static inline void __free_one_page(struct page *page,
VM_BUG_ON_PAGE(pfn & ((1 << order) - 1), page);
VM_BUG_ON_PAGE(bad_range(zone, page), page);
-continue_merging:
- while (order < max_order) {
+ while (order < MAX_ORDER - 1) {
if (compaction_capture(capc, page, order, migratetype)) {
__mod_zone_freepage_state(zone, -(1 << order),
migratetype);
@@ -1082,6 +1080,22 @@ static inline void __free_one_page(struct page *page,
if (!page_is_buddy(page, buddy, order))
goto done_merging;
+
+ if (unlikely(order >= pageblock_order)) {
+ /*
+ * We want to prevent merge between freepages on pageblock
+ * without fallbacks and normal pageblock. Without this,
+ * pageblock isolation could cause incorrect freepage or CMA
+ * accounting or HIGHATOMIC accounting.
+ */
+ int buddy_mt = get_pageblock_migratetype(buddy);
+
+ if (migratetype != buddy_mt
+ && (!migratetype_is_mergeable(migratetype) ||
+ !migratetype_is_mergeable(buddy_mt)))
+ goto done_merging;
+ }
+
/*
* Our buddy is free or it is CONFIG_DEBUG_PAGEALLOC guard page,
* merge with it and move up one order.
@@ -1095,32 +1109,6 @@ static inline void __free_one_page(struct page *page,
pfn = combined_pfn;
order++;
}
- if (order < MAX_ORDER - 1) {
- /* If we are here, it means order is >= pageblock_order.
- * We want to prevent merge between freepages on pageblock
- * without fallbacks and normal pageblock. Without this,
- * pageblock isolation could cause incorrect freepage or CMA
- * accounting or HIGHATOMIC accounting.
- *
- * We don't want to hit this code for the more frequent
- * low-order merging.
- */
- int buddy_mt;
-
- buddy_pfn = __find_buddy_pfn(pfn, order);
- buddy = page + (buddy_pfn - pfn);
-
- if (!page_is_buddy(page, buddy, order))
- goto done_merging;
- buddy_mt = get_pageblock_migratetype(buddy);
-
- if (migratetype != buddy_mt
- && (!migratetype_is_mergeable(migratetype) ||
- !migratetype_is_mergeable(buddy_mt)))
- goto done_merging;
- max_order = order + 1;
- goto continue_merging;
- }
done_merging:
set_buddy_order(page, order);
--
2.35.1
next reply other threads:[~2022-04-01 18:11 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-01 18:11 Zi Yan [this message]
2022-04-01 18:11 ` [PATCH v2 2/2] mm: wrap __find_buddy_pfn() with a necessary buddy page validation Zi Yan
2022-04-01 18:29 ` Linus Torvalds
2022-04-01 18:56 ` Zi Yan
2022-04-01 19:01 ` Linus Torvalds
2022-04-01 19:25 ` Zi Yan
2022-04-01 22:33 ` Vlastimil Babka
2022-04-01 22:14 ` [PATCH v2 1/2] mm: page_alloc: simplify pageblock migratetype check in __free_one_page() Vlastimil Babka
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