From: Rik van Riel <riel@surriel.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
kernel-team@fb.com, Anshuman Khandual <anshuman.khandual@arm.com>,
Mel Gorman <mgorman@techsingularity.net>,
Vlastimil Babka <vbabka@suse.cz>, Qian Cai <cai@lca.pw>,
Roman Gushchin <guro@fb.com>
Subject: [PATCH] mm,cma: remove pfn_range_valid_contig
Date: Fri, 6 Mar 2020 17:06:47 -0500 [thread overview]
Message-ID: <20200306170647.455a2db3@imladris.surriel.com> (raw)
The function pfn_range_valid_contig checks whether all memory in the
target area is free. This causes unnecessary CMA failures, since
alloc_contig_range will migrate movable memory out of a target range,
and has its own sanity check early on in has_unmovable_pages, which
is called from start_isolate_page_range & set_migrate_type_isolate.
Relying on that has_unmovable_pages call simplifies the CMA code and
results in an increased success rate of CMA allocations.
Signed-off-by: Rik van Riel <riel@surriel.com>
---
mm/page_alloc.c | 47 +++--------------------------------------------
1 file changed, 3 insertions(+), 44 deletions(-)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 0fb3c1719625..75e84907d8c6 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -8539,32 +8539,6 @@ static int __alloc_contig_pages(unsigned long start_pfn,
gfp_mask);
}
-static bool pfn_range_valid_contig(struct zone *z, unsigned long start_pfn,
- unsigned long nr_pages)
-{
- unsigned long i, end_pfn = start_pfn + nr_pages;
- struct page *page;
-
- for (i = start_pfn; i < end_pfn; i++) {
- page = pfn_to_online_page(i);
- if (!page)
- return false;
-
- if (page_zone(page) != z)
- return false;
-
- if (PageReserved(page))
- return false;
-
- if (page_count(page) > 0)
- return false;
-
- if (PageHuge(page))
- return false;
- }
- return true;
-}
-
static bool zone_spans_last_pfn(const struct zone *zone,
unsigned long start_pfn, unsigned long nr_pages)
{
@@ -8605,28 +8579,13 @@ struct page *alloc_contig_pages(unsigned long nr_pages, gfp_t gfp_mask,
zonelist = node_zonelist(nid, gfp_mask);
for_each_zone_zonelist_nodemask(zone, z, zonelist,
gfp_zone(gfp_mask), nodemask) {
- spin_lock_irqsave(&zone->lock, flags);
-
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)) {
- /*
- * We release the zone lock here because
- * alloc_contig_range() will also lock the zone
- * at some point. If there's an allocation
- * spinning on this lock, it may win the race
- * and cause alloc_contig_range() to fail...
- */
- spin_unlock_irqrestore(&zone->lock, flags);
- ret = __alloc_contig_pages(pfn, nr_pages,
- gfp_mask);
- if (!ret)
- return pfn_to_page(pfn);
- spin_lock_irqsave(&zone->lock, flags);
- }
+ ret = __alloc_contig_pages(pfn, nr_pages, gfp_mask);
+ if (!ret)
+ return pfn_to_page(pfn);
pfn += nr_pages;
}
- spin_unlock_irqrestore(&zone->lock, flags);
}
return NULL;
}
--
2.24.1
next reply other threads:[~2020-03-06 22:06 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-06 22:06 Rik van Riel [this message]
2020-03-06 22:22 ` [PATCH] mm,cma: remove pfn_range_valid_contig Rik van Riel
2020-03-11 8:40 ` Vlastimil Babka
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