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

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Message-ID: <BA0FE1EC-F17E-4AA3-80BA-10357E8C8B95@oracle.com>
Date:   Tue, 19 Dec 2017 09:52:31 -0500
From:   Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
To:     Christian König 
        <ckoenig.leichtzumerken@...il.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] swiotlb: suppress warning when __GFP_NOWARN is set.

On December 19, 2017 9:32:55 AM EST, "Christian König" <ckoenig.leichtzumerken@...il.com> wrote:
>TTM tries to allocate coherent memory in chunks of 2MB first to improve
>TLB efficiency and falls back to allocating 4K pages if that fails.
>
>Suppress the warning when the 2MB allocations fails since there is a
>valid fall back path.
>
>Signed-off-by: Christian König <christian.koenig@....com>

Is there an Reported by or such needed?

>---
> lib/swiotlb.c | 8 +++++---
> 1 file changed, 5 insertions(+), 3 deletions(-)
>
>diff --git a/lib/swiotlb.c b/lib/swiotlb.c
>index cea19aaf303c..63a44fb29ce6 100644
>--- a/lib/swiotlb.c
>+++ b/lib/swiotlb.c
>@@ -769,9 +769,11 @@ swiotlb_alloc_coherent(struct device *hwdev,
>size_t size,
> 	return ret;
> 
> err_warn:
>-	pr_warn("swiotlb: coherent allocation failed for device %s
>size=%zu\n",
>-		dev_name(hwdev), size);
>-	dump_stack();
>+	if (!(flags & __GFP_NOWARN)) {
>+		pr_warn("swiotlb: coherent allocation failed for device %s
>size=%zu\n",
>+			dev_name(hwdev), size);
>+		dump_stack();
>+	}

Ok, let me queue it up.
> 
> 	return NULL;
> }