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Date: Sat, 6 Jul 2024 08:08:18 +0200
From: Christoph Hellwig <hch@lst.de>
To: Leon Romanovsky <leon@kernel.org>
Cc: Christoph Hellwig <hch@lst.de>, Robin Murphy <robin.murphy@arm.com>,
	Jens Axboe <axboe@kernel.dk>, Jason Gunthorpe <jgg@ziepe.ca>,
	Joerg Roedel <joro@8bytes.org>, Will Deacon <will@kernel.org>,
	Keith Busch <kbusch@kernel.org>, "Zeng, Oak" <oak.zeng@intel.com>,
	Chaitanya Kulkarni <kch@nvidia.com>,
	Sagi Grimberg <sagi@grimberg.me>,
	Bjorn Helgaas <bhelgaas@google.com>,
	Logan Gunthorpe <logang@deltatee.com>,
	Yishai Hadas <yishaih@nvidia.com>,
	Shameer Kolothum <shameerali.kolothum.thodi@huawei.com>,
	Kevin Tian <kevin.tian@intel.com>,
	Alex Williamson <alex.williamson@redhat.com>,
	Marek Szyprowski <m.szyprowski@samsung.com>,
	=?iso-8859-1?B?Suly9G1l?= Glisse <jglisse@redhat.com>,
	Andrew Morton <akpm@linux-foundation.org>,
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	linux-nvme@lists.infradead.org, linux-pci@vger.kernel.org,
	kvm@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [RFC PATCH v1 18/18] nvme-pci: use new dma API
Message-ID: <20240706060818.GA13470@lst.de>
References: <cover.1719909395.git.leon@kernel.org> <47eb0510b0a6aa52d9f5665d75fa7093dd6af53f.1719909395.git.leon@kernel.org> <249ec228-4ffd-4121-bd51-f4a19275fee1@arm.com> <20240704171602.GE95824@unreal> <20240705055806.GA11885@lst.de> <20240705184846.GF95824@unreal>
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User-Agent: Mutt/1.5.17 (2007-11-01)

On Fri, Jul 05, 2024 at 09:48:46PM +0300, Leon Romanovsky wrote:
> In that case the flow is dma_map_sg()->iommu_dma_map_sg()->dev_use_sg_swiotlb().

Even for that you'll still need to check the first and last entry
for being kmalloc misaligned if we assume that all middle entries are
aligned (which for NVMe they have to, but we're probably better off
figuring out a way to enforce that).