linux-kernel - Re: [PATCH v2 1/7] kernel/resource: make release_mem_region

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Date:   Tue, 15 Sep 2020 11:15:53 +0200
From:   David Hildenbrand <david@...hat.com>
To:     Wei Yang <richard.weiyang@...ux.alibaba.com>
Cc:     linux-kernel@...r.kernel.org,
        virtualization@...ts.linux-foundation.org, linux-mm@...ck.org,
        linux-hyperv@...r.kernel.org, xen-devel@...ts.xenproject.org,
        linux-acpi@...r.kernel.org, linux-nvdimm@...ts.01.org,
        linux-s390@...r.kernel.org,
        Andrew Morton <akpm@...ux-foundation.org>,
        Michal Hocko <mhocko@...e.com>,
        Dan Williams <dan.j.williams@...el.com>,
        Jason Gunthorpe <jgg@...pe.ca>,
        Kees Cook <keescook@...omium.org>,
        Ard Biesheuvel <ardb@...nel.org>,
        Pankaj Gupta <pankaj.gupta.linux@...il.com>,
        Baoquan He <bhe@...hat.com>
Subject: Re: [PATCH v2 1/7] kernel/resource: make
 release_mem_region_adjustable() never fail

On 15.09.20 11:06, Wei Yang wrote:
> On Tue, Sep 15, 2020 at 09:35:30AM +0200, David Hildenbrand wrote:
>>
>>>> static int __ref try_remove_memory(int nid, u64 start, u64 size)
>>>> {
>>>> 	int rc = 0;
>>>> @@ -1777,7 +1757,7 @@ static int __ref try_remove_memory(int nid, u64 start, u64 size)
>>>> 		memblock_remove(start, size);
>>>> 	}
>>>>
>>>> -	__release_memory_resource(start, size);
>>>> +	release_mem_region_adjustable(&iomem_resource, start, size);
>>>>
>>>
>>> Seems the only user of release_mem_region_adjustable() is here, can we move
>>> iomem_resource into the function body? Actually, we don't iterate the resource
>>> tree from any level. We always start from the root.
>>
>> You mean, making iomem_resource implicit? I can spot that something
>> similar was done for
>>
>> #define devm_release_mem_region(dev, start, n) \
>> 	__devm_release_region(dev, &iomem_resource, (start), (n))
>>
> 
> What I prefer is remove iomem_resource from the parameter list. Just use is in
> the function body.
> 
> For the example you listed, __release_region() would have varies of *parent*,
> which looks reasonable to keep it here.

Yeah I got that ("making iomem_resource implicit"), as I said:

>> I'll send an addon patch for that, ok? - thanks.

-- 
Thanks,

David / dhildenb