linux-kernel - [PATCH v4 8/9] mm/page_alloc: make alloc_contig

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Date:   Fri, 10 Mar 2023 16:38:54 -0800
From:   Doug Berger <opendmb@...il.com>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     Jonathan Corbet <corbet@....net>, Mike Rapoport <rppt@...nel.org>,
        Borislav Petkov <bp@...e.de>,
        "Paul E. McKenney" <paulmck@...nel.org>,
        Randy Dunlap <rdunlap@...radead.org>,
        Neeraj Upadhyay <quic_neeraju@...cinc.com>,
        Damien Le Moal <damien.lemoal@...nsource.wdc.com>,
        Kim Phillips <kim.phillips@....com>,
        "Steven Rostedt (Google)" <rostedt@...dmis.org>,
        Michal Hocko <mhocko@...e.com>,
        Johannes Weiner <hannes@...xchg.org>,
        Vlastimil Babka <vbabka@...e.cz>,
        KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
        Mel Gorman <mgorman@...e.de>,
        Muchun Song <songmuchun@...edance.com>,
        Mike Kravetz <mike.kravetz@...cle.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        David Hildenbrand <david@...hat.com>,
        Oscar Salvador <osalvador@...e.de>,
        Joonsoo Kim <iamjoonsoo.kim@....com>,
        Sukadev Bhattiprolu <quic_sukadev@...cinc.com>,
        Rik van Riel <riel@...riel.com>,
        Roman Gushchin <guro@...com>, Minchan Kim <minchan@...nel.org>,
        Chris Goldsworthy <quic_cgoldswo@...cinc.com>,
        "Georgi Djakov" <quic_c_gdjako@...cinc.com>,
        linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org, Doug Berger <opendmb@...il.com>
Subject: [PATCH v4 8/9] mm/page_alloc: make alloc_contig_pages DMB aware

Designated Movable Blocks are skipped when attempting to allocate
contiguous pages. Doing per page validation across all spanned
pages within a zone can be extra inefficient when Designated
Movable Blocks create large overlaps between zones. Use
dmb_intersects() within pfn_range_valid_contig as an early check
to signal the range is not valid.

The zone_movable_pfn array which represents the start of non-
overlapped ZONE_MOVABLE on the node is now preserved to be used
at runtime to skip over any DMB-only portion of the zone.

Signed-off-by: Doug Berger <opendmb@...il.com>
---
 mm/page_alloc.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 26846a9a9fc4..d4358d19d5a1 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -417,7 +417,7 @@ static unsigned long required_movablecore __initdata;
 static unsigned long required_movablecore_percent __initdata;
 static unsigned long min_dmb_pfn[MAX_NUMNODES] __initdata;
 static unsigned long max_dmb_pfn[MAX_NUMNODES] __initdata;
-static unsigned long zone_movable_pfn[MAX_NUMNODES] __initdata;
+static unsigned long zone_movable_pfn[MAX_NUMNODES];
 bool mirrored_kernelcore __initdata_memblock;
 
 /* movable_zone is the "real" zone pages in ZONE_MOVABLE are taken from */
@@ -9503,6 +9503,9 @@ static bool pfn_range_valid_contig(struct zone *z, unsigned long start_pfn,
 	unsigned long i, end_pfn = start_pfn + nr_pages;
 	struct page *page;
 
+	if (dmb_intersects(start_pfn, end_pfn))
+		return false;
+
 	for (i = start_pfn; i < end_pfn; i++) {
 		page = pfn_to_online_page(i);
 		if (!page)
@@ -9559,7 +9562,10 @@ struct page *alloc_contig_pages(unsigned long nr_pages, gfp_t gfp_mask,
 					gfp_zone(gfp_mask), nodemask) {
 		spin_lock_irqsave(&zone->lock, flags);
 
-		pfn = ALIGN(zone->zone_start_pfn, nr_pages);
+		if (zone_idx(zone) == ZONE_MOVABLE && zone_movable_pfn[nid])
+			pfn = ALIGN(zone_movable_pfn[nid], nr_pages);
+		else
+			pfn = ALIGN(zone->zone_start_pfn, nr_pages);
 		while (zone_spans_last_pfn(zone, pfn, nr_pages)) {
 			if (pfn_range_valid_contig(zone, pfn, nr_pages)) {
 				/*
-- 
2.34.1