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

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Message-ID: <aRw9zbfD6Jf9_M2E@pc636>
Date: Tue, 18 Nov 2025 10:35:09 +0100
From: Uladzislau Rezki <urezki@...il.com>
To: "Vishal Moola (Oracle)" <vishal.moola@...il.com>
Cc: linux-kernel@...r.kernel.org, linux-mm@...ck.org, bpf@...r.kernel.org,
	Uladzislau Rezki <urezki@...il.com>,
	Christoph Hellwig <hch@...radead.org>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH v3 2/4] mm/vmalloc: Add a helper to optimize vmalloc
 allocation gfps

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@...il.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@...il.com>

--
Uladzislau Rezki