linux-kernel - Re: [PATCH 2/4] mm/memory-hotplug: allow memory resources to be children

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Message-ID: <b1f22eda-b52f-af20-637f-b45971a12d33@intel.com>
Date:   Wed, 23 Jan 2019 12:03:54 -0800
From:   Dave Hansen <dave.hansen@...el.com>
To:     Jerome Glisse <jglisse@...hat.com>
Cc:     Dave Hansen <dave.hansen@...ux.intel.com>, dave@...1.net,
        dan.j.williams@...el.com, dave.jiang@...el.com, zwisler@...nel.org,
        vishal.l.verma@...el.com, thomas.lendacky@....com,
        akpm@...ux-foundation.org, mhocko@...e.com,
        linux-nvdimm@...ts.01.org, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org, ying.huang@...el.com, fengguang.wu@...el.com,
        bp@...e.de, bhelgaas@...gle.com, baiyaowei@...s.chinamobile.com,
        tiwai@...e.de
Subject: Re: [PATCH 2/4] mm/memory-hotplug: allow memory resources to be
 children

On 1/16/19 3:38 PM, Jerome Glisse wrote:
> So right now i would rather that we keep properly reporting this
> hazard so that at least we know it failed because of that. This
> also include making sure that we can not register private memory
> as a child of an un-busy resource that does exist but might not
> have yet been claim by its rightful owner.

I can definitely keep the warning in.  But, I don't think there's a
chance of HMM registering a IORES_DESC_DEVICE_PRIVATE_MEMORY region as
the child of another.  The region_intersects() check *should* find that:

>         for (; addr > size && addr >= iomem_resource.start; addr -= size) {
>                 ret = region_intersects(addr, size, 0, IORES_DESC_NONE);
>                 if (ret != REGION_DISJOINT)
>                         continue;