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From: Laura Abbott <labbott@redhat.com>
To: "Zengtao (B)" <prime.zeng@hisilicon.com>,
	"sumit.semwal@linaro.org" <sumit.semwal@linaro.org>
Cc: "gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>,
	"arve@android.com" <arve@android.com>,
	"riandrews@android.com" <riandrews@android.com>,
	"devel@driverdev.osuosl.org" <devel@driverdev.osuosl.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: Using ion memory for direct-io
Date: Mon, 17 Apr 2017 09:13:48 -0700	[thread overview]
Message-ID: <2b0d4915-3705-dce5-d9dd-066549050bfc@redhat.com> (raw)
In-Reply-To: <678F3D1BB717D949B966B68EAEB446ED0BCCFFC4@dggeml511-mbs.china.huawei.com>

On 04/14/2017 02:18 AM, Zengtao (B) wrote:
> Hi 
> 
> Currently, the ion mapped to userspace will be forced with VM_IO and VM_PFNMAP flags.
> When I use the ion memory to do the direct-io, it will fail when reaching the get_user_pages,
> 
> Back to the VM_IO and VM_PFNMAP flag, there two flags are introduced by the remap_pfn_range called 
> by the ion_heap_mmap_user.
> 
> From my point of view, all ion memory(cma/vmalloc/system heap) are managed by linux vm, it
> is not reasonable to have the VM_IO and VM_PFNMAP flag, but I don't any suitable function
> to replace the remap_pfn_range, any suggestions?
> 
> Thanks && Regards
> 
> Zengtao 
> 

The carveout heap is omitted from your list of 'all ion memory'. At one
time, carveout memory was not backed by struct pages so I suspect
this is a holdover from then. This would probably be better served
by using vm_insert_page and handling higher order pages properly.

Thanks,
Laura

  reply	other threads:[~2017-04-17 16:13 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-04-14  9:18 Zengtao (B)
2017-04-17 16:13 ` Laura Abbott [this message]
     [not found]   ` <678F3D1BB717D949B966B68EAEB446ED0BCD4CDF@dggeml511-mbs.china.huawei.com>
2017-04-18 15:56     ` 答复: " Laura Abbott

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