<div dir="ltr">Arun,<div><br></div><div>What seems to have done the trick is calling memblock_remove() followed by a call to request_mem_region(). This creates a hole which can be confirmed in the output of /proc/iomem.</div><div><br></div><div>Do you see any issue with this approach?</div><div><br></div><div>-Thanks</div><div>Nikhil</div></div><div class="gmail_extra"><br><div class="gmail_quote">On Tue, Sep 27, 2016 at 4:14 PM, Arun Sudhilal <span dir="ltr"><<a href="mailto:getarunks@gmail.com" target="_blank">getarunks@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Hello Nikhil,<br>
<span class=""><br>
On Fri, Sep 9, 2016 at 7:01 AM, Nikhil Utane<br>
<<a href="mailto:nikhil.subscribed@gmail.com">nikhil.subscribed@gmail.com</a>> wrote:<br>
> I want to reserve a physical memory page with a fixed PFN. I do not want<br>
> this page to be used by anyone else. I am calling memblock_reserve() to<br>
> supposedly reserve the page. I am writing some content into this page. What<br>
> I see is that during some runs the content of this page is modified (either<br>
> fully or sometimes partially). In few runs, I see it as intact. Is it<br>
> expected that even after calling memblock_reserve() the kernel can allocate<br>
> this physical page for any other purpose? How is memblock_remove() different<br>
> from memblock_reserve? I tried reading up but didn't see any useful<br>
> information. What I understood is memblock_remove will completely remove<br>
> from kernel's allocation mechanism. Should I then be using remove instead of<br>
> reserve?<br>
<br>
</span>when a DT entry is added to #reserved-memory node, what<br>
drivers/of/fdt.c does is to call memblock_remove() and<br>
memblock_reserve().<br>
This happens after the memblock driver is initialized but before buddy<br>
allocator up. Did you try this approach? This should work for you.<br>
<br>
Only option once the kernel boot is complete is to try out the<br>
technique what mm/memory_hotplug.c does while offline memory.<br>
isolate_page_range and then migrate.<br>
<br>
Regards,<br>
Arun<br>
<div class="HOEnZb"><div class="h5"><br>
<br>
><br>
> -Thanks<br>
> Nikhil<br>
><br>
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