linux-kernel - Re: [PATCH] swiotlb: suppress warning when __GFP

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Message-ID: <20180104132919.GA7213@infradead.org>
Date:   Thu, 4 Jan 2018 05:29:19 -0800
From:   Christoph Hellwig <hch@...radead.org>
To:     Christian König 
        <ckoenig.leichtzumerken@...il.com>
Cc:     konrad.wilk@...cle.com, linux-kernel@...r.kernel.org,
        hch@...radead.org
Subject: Re: [PATCH] swiotlb: suppress warning when __GFP_NOWARN is set v5

> @@ -713,6 +713,7 @@ void *
>  swiotlb_alloc_coherent(struct device *hwdev, size_t size,
>  		       dma_addr_t *dma_handle, gfp_t flags)
>  {
> +	bool warn = !(flags & __GFP_NOWARN);

This is still wrong.  __GFP_NOWARN has no meaning for DMA coherent
allocations, and if a driver expects it to do anything it's doing it
wrong.  This needs to check for DMA_ATTR_NO_WARN, and thus get the attrs
passed.