From: dann frazier <dann.frazier@canonical.com>
To: Christoph Hellwig <hch@lst.de>
Cc: Xinwei Kong <kong.kongxinwei@hisilicon.com>,
linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org,
Robin Murphy <robin.murphy@arm.com>,
linux-arm-kernel@lists.infradead.org,
Marek Szyprowski <m.szyprowski@samsung.com>
Subject: [RFC] arm64: swiotlb: cma_alloc error spew
Date: Wed, 17 Apr 2019 14:48:17 -0600 [thread overview]
Message-ID: <20190417204817.GA28897@xps13.dannf> (raw)
hey,
I'm seeing an issue on a couple of arm64 systems[*] where they spew
~10K "cma: cma_alloc: alloc failed" messages at boot. The errors are
non-fatal, and bumping up cma to a large enough size (~128M) gets rid
of them - but that seems suboptimal. Bisection shows that this started
after commit fafadcd16595 ("swiotlb: don't dip into swiotlb pool for
coherent allocations"). It looks like __dma_direct_alloc_pages()
is opportunistically using CMA memory but falls back to non-CMA if CMA
disabled or unavailable. I've demonstrated that this fallback is
indeed returning a valid pointer. So perhaps the issue is really just
the warning emission.
The following naive patch solves the problem for me - just silence the
cma errors, since it looks like a soft error. But is there a better
approach?
[*] APM X-Gene & HiSilicon Hi1620 w/ SMMU disabled
diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c
index 6310ad01f915b..0324aa606c173 100644
--- a/kernel/dma/direct.c
+++ b/kernel/dma/direct.c
@@ -112,7 +112,7 @@ struct page *__dma_direct_alloc_pages(struct device *dev, size_t size,
/* CMA can be used only in the context which permits sleeping */
if (gfpflags_allow_blocking(gfp)) {
page = dma_alloc_from_contiguous(dev, count, page_order,
- gfp & __GFP_NOWARN);
+ true);
if (page && !dma_coherent_ok(dev, page_to_phys(page), size)) {
dma_release_from_contiguous(dev, page, count);
page = NULL;
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next reply other threads:[~2019-04-17 20:48 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-17 20:48 dann frazier [this message]
2019-04-23 11:32 ` [RFC] arm64: swiotlb: cma_alloc error spew Robin Murphy
2019-04-23 18:03 ` dann frazier
2019-04-24 0:39 ` dann frazier
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