On 10/11/2018 03:44 AM, Rock Lee wrote:
On Thu, Oct 11, 2018 at 4:12 PM Dan Carpenter <dan.carpenter@xxxxxxxxxx> wrote:
On Thu, Oct 11, 2018 at 11:24:49AM +0800, Rock Lee wrote:
Hi
I tested direct io with a ion allocated buffer, got a -EFAULT
error. It turned out that ion_mmap() set VM_IO & VM_PFNMAP, but
check_vma_flags() (do_direct_IO() calls it) doesn't allow that VMA has
these flags set. Could you give me any hit that could solve this
issue?
You must be using an old kernel because ion_mmap() was changed in April.
Yes, I am using linux-4.4 which is a little old. Even in linux-4.18,
ion_mmap() still callls remap_pfn_range() if the heap is
carvout/system/cma/chunk. But remap_pfn_range() set VM_IO & IO_PFNMAP
as well.
Yes, I don't think there's a way around this without moving away
from remap_pfn_range. I thought there was a reason why we
needed to use remap_pfn_range but it's escaping me. If you wanted
to do the work to move away from remap_pfn_range, that would
be appreciated.
Thanks,
Laura
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