[PATCH v6 2/6] mm/memplicy: add page allocation function for MPOL_PREFERRED_MANY policy

From: Feng Tang
Date: Mon Jul 12 2021 - 05:05:01 EST


The semantics of MPOL_PREFERRED_MANY is similar to MPOL_PREFERRED,
that it will first try to allocate memory from the preferred node(s),
and fallback to all nodes in system when first try fails.

Add a dedicated function for it just like 'interleave' policy.

Link: https://lore.kernel.org/r/20200630212517.308045-9-ben.widawsky@xxxxxxxxx
Suggested-by: Michal Hocko <mhocko@xxxxxxxx>
Co-developed-by: Ben Widawsky <ben.widawsky@xxxxxxxxx>
Signed-off-by: Ben Widawsky <ben.widawsky@xxxxxxxxx>
Signed-off-by: Feng Tang <feng.tang@xxxxxxxxx>
---
mm/mempolicy.c | 19 +++++++++++++++++++
1 file changed, 19 insertions(+)

diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 17b5800b7dcc..d17bf018efcc 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -2153,6 +2153,25 @@ static struct page *alloc_page_interleave(gfp_t gfp, unsigned order,
return page;
}

+static struct page *alloc_page_preferred_many(gfp_t gfp, unsigned int order,
+ struct mempolicy *pol)
+{
+ struct page *page;
+
+ /*
+ * This is a two pass approach. The first pass will only try the
+ * preferred nodes but skip the direct reclaim and allow the
+ * allocation to fail, while the second pass will try all the
+ * nodes in system.
+ */
+ page = __alloc_pages(((gfp | __GFP_NOWARN) & ~__GFP_DIRECT_RECLAIM),
+ order, first_node(pol->nodes), &pol->nodes);
+ if (!page)
+ page = __alloc_pages(gfp, order, numa_node_id(), NULL);
+
+ return page;
+}
+
/**
* alloc_pages_vma - Allocate a page for a VMA.
* @gfp: GFP flags.
--
2.7.4