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Message-ID: <a76cb262-a24f-e113-5680-2025aa143ee6@arm.com>
Date: Fri, 16 Dec 2022 11:40:57 +0000
From: Robin Murphy <robin.murphy@....com>
To: Christoph Hellwig <hch@....de>,
Mikhail Gavrilov <mikhail.v.gavrilov@...il.com>
Cc: Takashi Iwai <tiwai@...e.de>, alsa-devel@...a-project.org,
m.szyprowski@...sung.com,
Linux List Kernel Mailing <linux-kernel@...r.kernel.org>,
iommu@...ts.linux.dev
Subject: Re: [6.2][regression] after commit
ffcb754584603adf7039d7972564fbf6febdc542 all sound devices disappeared (due
BUG at mm/page_alloc.c:3592!)
On 2022-12-16 06:46, Christoph Hellwig wrote:
> Ok, it seems like the sound noncontig alloc code that I already
> commented on as potentially bogus GFP_GOMP mapping trips this. I think
> for now the right thing would be to revert the hunk in dma-iommu.c
> (see patch below). The other thing to try would be to remove both
> uses GFP_COMP in sound/core/memalloc.c, which should have the same
> effect.
Or we explicitly strip the flag in dma_alloc_noncontiguous() (and maybe
dma_alloc_pages() as well) for consistency with dma_alloc_attrs(). That
seems like it might be the most robust option.
Robin.
> diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
> index 9297b741f5e80e..f798c44e090337 100644
> --- a/drivers/iommu/dma-iommu.c
> +++ b/drivers/iommu/dma-iommu.c
> @@ -744,9 +744,6 @@ static struct page **__iommu_dma_alloc_pages(struct device *dev,
> /* IOMMU can map any pages, so himem can also be used here */
> gfp |= __GFP_NOWARN | __GFP_HIGHMEM;
>
> - /* It makes no sense to muck about with huge pages */
> - gfp &= ~__GFP_COMP;
> -
> while (count) {
> struct page *page = NULL;
> unsigned int order_size;
>
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