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Message-ID: <Y8p7WjBpNt5q4W/Z@ubun2204.myguest.virtualbox.org>
Date: Fri, 20 Jan 2023 17:00:34 +0530
From: Deepak R Varma <drv@...lo.com>
To: Russell King <linux@...linux.org.uk>,
linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Cc: Saurabh Singh Sengar <ssengar@...rosoft.com>,
Praveen Kumar <kumarpraveen@...ux.microsoft.com>
Subject: Re: [PATCH] ARM/dma-mapping: use kvzalloc for fallback memory
allocation need
On Tue, Dec 20, 2022 at 10:55:11AM +0530, Deepak R Varma wrote:
> When the memory sizes are not known upfront, it is preferred to use the
> kvzalloc helper function instead of direct conditional evaluation of
> size and kzalloc/vzalloc fallback design. The kvzalloc helper function
> in this case is more efficient as it avoids indefinite kzalloc retries
> when a small memory size is needed but is unavailable.
> This LWN article has further details on the advantages of using
> kvzalloc in case of fallback memory allocation needs:
> https://lwn.net/Articles/711653/
>
> This patch proposal is based on following Coccinelle warning using the
> kvmalloc.cocci semantic patch.
>
> arch/arm/mm/dma-mapping.c:858:28-29: WARNING opportunity for kvmalloc
>
> Signed-off-by: Deepak R Varma <drv@...lo.com>
Hello,
May I please request a review and feedback on this patch proposal?
Thank you,
./drv
> ---
> Note: The patch proposal is compile tested only.
>
> arch/arm/mm/dma-mapping.c | 5 +----
> 1 file changed, 1 insertion(+), 4 deletions(-)
>
> diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
> index c135f6e37a00..2b79af377a81 100644
> --- a/arch/arm/mm/dma-mapping.c
> +++ b/arch/arm/mm/dma-mapping.c
> @@ -855,10 +855,7 @@ static struct page **__iommu_alloc_buffer(struct device *dev, size_t size,
> int i = 0;
> int order_idx = 0;
>
> - if (array_size <= PAGE_SIZE)
> - pages = kzalloc(array_size, GFP_KERNEL);
> - else
> - pages = vzalloc(array_size);
> + pages = kvzalloc(array_size, GFP_KERNEL);
> if (!pages)
> return NULL;
>
> --
> 2.34.1
>
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