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Date: Fri, 27 Mar 2020 18:06:47 +0100
From: Christoph Hellwig <hch@lst.de>
To: Alexander Potapenko <glider@google.com>
Cc: Christoph Hellwig <hch@lst.de>,
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Subject: Re: [PATCH v5 34/38] kmsan: dma: unpoison memory mapped by
 dma_direct_map_page()
Message-ID: <20200327170647.GA22758@lst.de>
References: <20200325161249.55095-1-glider@google.com> <20200325161249.55095-35-glider@google.com> <20200325161905.GA19868@lst.de> <CAG_fn=WjuC+uRyc4ocQ9YLOkZtLY8a+EnNZiVG5SsvczJBunLw@mail.gmail.com>
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On Fri, Mar 27, 2020 at 06:03:32PM +0100, Alexander Potapenko wrote:
> > Also the page
> > doesn't have to be mapped into kernel address space, you probably
> > want to pass the page to kmsan_handle_dma and throw in a highmem
> > check there.
> 
> Do you mean comparing the address to TASK_SIZE, or is there a more
> portable way to check that?

!PageHighMem(page) implies the page has a kernel direct mapping.