From: Jason Gunthorpe <jgg@nvidia.com>
To: Robin Murphy <robin.murphy@arm.com>
Cc: Lu Baolu <baolu.lu@linux.intel.com>,
Joerg Roedel <joro@8bytes.org>, Kevin Tian <kevin.tian@intel.com>,
Matthew Rosato <mjrosato@linux.ibm.com>,
Alex Williamson <alex.williamson@redhat.com>,
ath10k@lists.infradead.org, ath11k@lists.infradead.org,
Christian Borntraeger <borntraeger@linux.ibm.com>,
dri-devel@lists.freedesktop.org, iommu@lists.linux.dev,
kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
linux-arm-msm@vger.kernel.org, linux-media@vger.kernel.org,
linux-rdma@vger.kernel.org, linux-remoteproc@vger.kernel.org,
linux-s390@vger.kernel.org,
linux-stm32@st-md-mailman.stormreply.com,
linux-tegra@vger.kernel.org, linux-wireless@vger.kernel.org,
netdev@vger.kernel.org, nouveau@lists.freedesktop.org,
Niklas Schnelle <schnelle@linux.ibm.com>,
virtualization@lists.linux-foundation.org
Subject: Re: [PATCH 1/8] iommu: Add a gfp parameter to iommu_map()
Date: Fri, 6 Jan 2023 13:24:11 -0400 [thread overview]
Message-ID: <Y7hZOwerwljDKoQq@nvidia.com> (raw)
In-Reply-To: <4fd1b194-29ef-621d-4059-a8336058f217@arm.com>
On Fri, Jan 06, 2023 at 05:15:28PM +0000, Robin Murphy wrote:
> On 2023-01-06 16:42, Jason Gunthorpe wrote:
> > The internal mechanisms support this, but instead of exposting the gfp to
> > the caller it wrappers it into iommu_map() and iommu_map_atomic()
> >
> > Fix this instead of adding more variants for GFP_KERNEL_ACCOUNT.
>
> FWIW, since we *do* have two variants already, I think I'd have a mild
> preference for leaving the regular map calls as-is (i.e. implicit
> GFP_KERNEL), and just generalising the _atomic versions for the special
> cases.
I think it is just better to follow kernel convention and have
allocation functions include the GFP because it is a clear signal to
the user that there is an allocation hidden inside the API. The whole
point of gfp is not to have multitudes of every function for every
allocation mode.
There are not so many callers that it seems worth worrying about
removing the extra GFP_KERNEL argument.
> However, echoing the recent activity over on the DMA API side of things, I
> think it's still worth proactively constraining the set of permissible
> flags, lest we end up with more weird problems if stuff that doesn't really
> make sense, like GFP_COMP or zone flags, manages to leak through (that may
> have been part of the reason for having the current wrappers rather than a
> bare gfp argument in the first place, I forget now).
Yeah, that can be done
Thanks,
Jason
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next prev parent reply other threads:[~2023-01-06 17:32 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-06 16:42 [PATCH 0/8] Let iommufd charge IOPTE allocations to the memory cgroup Jason Gunthorpe
2023-01-06 16:42 ` [PATCH 1/8] iommu: Add a gfp parameter to iommu_map() Jason Gunthorpe
2023-01-06 17:15 ` Robin Murphy
2023-01-06 17:24 ` Jason Gunthorpe [this message]
2023-01-20 9:24 ` Joerg Roedel
2023-01-20 17:53 ` Jason Gunthorpe
2023-01-23 9:59 ` Joerg Roedel
2023-01-16 18:12 ` Jason Gunthorpe
2023-01-06 16:42 ` [PATCH 2/8] iommu: Remove iommu_map_atomic() Jason Gunthorpe
2023-01-06 16:42 ` [PATCH 3/8] iommu: Add a gfp parameter to iommu_map_sg() Jason Gunthorpe
2023-01-06 16:42 ` [PATCH 4/8] iommu/dma: Use the gfp parameter in __iommu_dma_alloc_noncontiguous() Jason Gunthorpe
2023-01-06 16:42 ` [PATCH 5/8] iommufd: Use GFP_KERNEL_ACCOUNT for iommu_map() Jason Gunthorpe
2023-01-06 16:42 ` [PATCH 6/8] iommu/intel: Add a gfp parameter to alloc_pgtable_page() Jason Gunthorpe
2023-01-17 3:35 ` Tian, Kevin
2023-01-17 13:30 ` Jason Gunthorpe
2023-01-18 1:18 ` Tian, Kevin
2023-01-18 15:15 ` Jason Gunthorpe
2023-01-06 16:42 ` [PATCH 7/8] iommu/intel: Support the gfp argument to the map_pages op Jason Gunthorpe
2023-01-17 3:38 ` Tian, Kevin
2023-01-17 8:35 ` Baolu Lu
2023-01-17 13:28 ` Jason Gunthorpe
2023-01-06 16:42 ` [PATCH 8/8] iommu/s390: Push the gfp parameter to the kmem_cache_alloc()'s Jason Gunthorpe
2023-01-17 8:49 ` Niklas Schnelle
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