Re: [PATCH v3 2/4] mm/vmalloc: Add a helper to optimize vmalloc allocation gfps

Uladzislau Rezki
2025-11-18T09:35:14Z

On Mon, Nov 17, 2025 at 09:35:28AM -0800, Vishal Moola (Oracle) wrote:
> 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@gmail.com>
> ---
> mm/vmalloc.c | 17 ++++++++++++++---
> 1 file changed, 14 insertions(+), 3 deletions(-)
>
> diff --git a/mm/vmalloc.c b/mm/vmalloc.c
> index 5dc467c6cab4..0929f4f53ffe 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
>
Reviewed-by: "Uladzislau Rezki (Sony)" <urezki@gmail.com>

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Uladzislau Rezki