linux-kernel - [RFC PATCH 2/4] mm/vmalloc: Add a helper to optimize vmalloc allocation gfps

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Message-ID: <20251030164330.44995-3-vishal.moola@gmail.com>
Date: Thu, 30 Oct 2025 09:43:28 -0700
From: "Vishal Moola (Oracle)" <vishal.moola@...il.com>
To: linux-kernel@...r.kernel.org,
	linux-mm@...ck.org
Cc: Uladzislau Rezki <urezki@...il.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Christoph Hellwig <hch@...radead.org>,
	"Vishal Moola (Oracle)" <vishal.moola@...il.com>
Subject: [RFC PATCH 2/4] mm/vmalloc: Add a helper to optimize vmalloc allocation gfps

vm_area_alloc_pages() attempts to use different gfp flags as a way
to optimize allocations. This has been done inline which makes things
harder to read.

Add a helper function to make the code more readable.

Signed-off-by: Vishal Moola (Oracle) <vishal.moola@...il.com>
---
 mm/vmalloc.c | 17 ++++++++++++++---
 1 file changed, 14 insertions(+), 3 deletions(-)

diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index b86c36d51833..76c060ef2bf7 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -3614,6 +3614,17 @@ void *vmap_pfn(unsigned long *pfns, unsigned int count, pgprot_t prot)
 EXPORT_SYMBOL_GPL(vmap_pfn);
 #endif /* CONFIG_VMAP_PFN */
 
+/*
+ * Helper for vmalloc to adjust the gfp flags for certain allocations.
+ */
+static inline gfp_t vmalloc_gfp_adjust(gfp_t flags, const bool large)
+{
+	flags |= __GFP_NOWARN;
+	if (large)
+		flags &= ~__GFP_NOFAIL;
+	return flags;
+}
+
 static inline unsigned int
 vm_area_alloc_pages(gfp_t gfp, int nid,
 		unsigned int order, unsigned int nr_pages, struct page **pages)
@@ -3852,9 +3863,9 @@ static void *__vmalloc_area_node(struct vm_struct *area, gfp_t gfp_mask,
 	 * Please note, the __vmalloc_node_range_noprof() falls-back
 	 * to order-0 pages if high-order attempt is unsuccessful.
 	 */
-	area->nr_pages = vm_area_alloc_pages((page_order ?
-		gfp_mask & ~__GFP_NOFAIL : gfp_mask) | __GFP_NOWARN,
-		node, page_order, nr_small_pages, area->pages);
+	area->nr_pages = vm_area_alloc_pages(
+			vmalloc_gfp_adjust(gfp_mask, page_order), node,
+			page_order, nr_small_pages, area->pages);
 
 	atomic_long_add(area->nr_pages, &nr_vmalloc_pages);
 	/* All pages of vm should be charged to same memcg, so use first one. */
-- 
2.51.1