linux-kernel - Re: [PATCH V3 3/3] s390/mm: Define arch_get_mappable

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Date:   Wed, 20 Jan 2021 11:39:49 +0100
From:   David Hildenbrand <david@...hat.com>
To:     Anshuman Khandual <anshuman.khandual@....com>, linux-mm@...ck.org,
        akpm@...ux-foundation.org, hca@...ux.ibm.com,
        catalin.marinas@....com
Cc:     Oscar Salvador <osalvador@...e.de>,
        Vasily Gorbik <gor@...ux.ibm.com>,
        Will Deacon <will@...nel.org>,
        Ard Biesheuvel <ardb@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        linux-arm-kernel@...ts.infradead.org, linux-s390@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH V3 3/3] s390/mm: Define arch_get_mappable_range()

On 20.01.21 09:28, Anshuman Khandual wrote:
> 
> 
> On 1/19/21 5:56 PM, David Hildenbrand wrote:
>> On 18.01.21 14:13, Anshuman Khandual wrote:
>>> This overrides arch_get_mappabble_range() on s390 platform which will be
>>> used with recently added generic framework. It modifies the existing range
>>> check in vmem_add_mapping() using arch_get_mappable_range(). It also adds a
>>> VM_BUG_ON() check that would ensure that memhp_range_allowed() has already
>>> been called on the hotplug path.
>>>
>>> Cc: Heiko Carstens <hca@...ux.ibm.com>
>>> Cc: Vasily Gorbik <gor@...ux.ibm.com>
>>> Cc: David Hildenbrand <david@...hat.com>
>>> Cc: linux-s390@...r.kernel.org
>>> Cc: linux-kernel@...r.kernel.org
>>> Acked-by: Heiko Carstens <hca@...ux.ibm.com>
>>> Signed-off-by: Anshuman Khandual <anshuman.khandual@....com>
>>> ---
>>>  arch/s390/mm/init.c |  1 +
>>>  arch/s390/mm/vmem.c | 15 ++++++++++++++-
>>>  2 files changed, 15 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/arch/s390/mm/init.c b/arch/s390/mm/init.c
>>> index 73a163065b95..97017a4bcc90 100644
>>> --- a/arch/s390/mm/init.c
>>> +++ b/arch/s390/mm/init.c
>>> @@ -297,6 +297,7 @@ int arch_add_memory(int nid, u64 start, u64 size,
>>>  	if (WARN_ON_ONCE(params->pgprot.pgprot != PAGE_KERNEL.pgprot))
>>>  		return -EINVAL;
>>>  
>>> +	VM_BUG_ON(!memhp_range_allowed(start, size, true));
>>>  	rc = vmem_add_mapping(start, size);
>>>  	if (rc)
>>>  		return rc;
>>> diff --git a/arch/s390/mm/vmem.c b/arch/s390/mm/vmem.c
>>> index 01f3a5f58e64..afc39ff1cc8d 100644
>>> --- a/arch/s390/mm/vmem.c
>>> +++ b/arch/s390/mm/vmem.c
>>> @@ -4,6 +4,7 @@
>>>   *    Author(s): Heiko Carstens <heiko.carstens@...ibm.com>
>>>   */
>>>  
>>> +#include <linux/memory_hotplug.h>
>>>  #include <linux/memblock.h>
>>>  #include <linux/pfn.h>
>>>  #include <linux/mm.h>
>>> @@ -532,11 +533,23 @@ void vmem_remove_mapping(unsigned long start, unsigned long size)
>>>  	mutex_unlock(&vmem_mutex);
>>>  }
>>>  
>>> +struct range arch_get_mappable_range(void)
>>> +{
>>> +	struct range memhp_range;
>>
>> You could do:
>>
>> memhp_range = {
>> 	.start = 0,
>> 	.end =  VMEM_MAX_PHYS - 1,
>> };
>>
>> Similar in the arm64 patch.
> 
> There is a comment block just before this assignment on arm64. Also
> it seems like code style preference and Heiko had originally agreed
> on this particular patch. Could we just leave it unchanged please ?

That's not how review works. But as I said, "You could do".

-- 
Thanks,

David / dhildenb