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Date:   Wed, 23 Nov 2022 09:53:45 +0800
MIME-Version: 1.0
Subject: Re: [for-next PATCH 1/1] RDMA/rxe: sgt_append from ib_umem_get is not
 highmem
To:     Jason Gunthorpe <jgg@ziepe.ca>
Cc:     Zhu Yanjun <yanjun.zhu@intel.com>, zyjzyj2000@gmail.com,
        leon@kernel.org, linux-rdma@vger.kernel.org
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From:   Yanjun Zhu <yanjun.zhu@linux.dev>
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在 2022/11/22 22:06, Jason Gunthorpe 写道:
> On Tue, Nov 22, 2022 at 12:07:06PM +0800, Yanjun Zhu wrote:
>
>> But can user space access these high memory? From "Understanding the Linux
>> Kernel", third edition, it seems that it is in kernel space.
> Yes, "highmem" is effecitvely the ability to have a struct page * that
> is not mapped into the kernel address space, but is mapped into a
> userspace process address sspace.
Got it. I am interested in this "highmem is mapped into a

userspace process address space.".


Would you like to share some documents, links or source code about this 
with me?


I want to delve into this "highmem is mapped into a

userspace process address space."

Thanks and Regards,

Zhu Yanjun


>
> Jason