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

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Message-ID: <cbdb32af-74af-ceb2-fa68-3912ef20d784@redhat.com>
Date:   Tue, 19 Jan 2021 13:26:52 +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 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.

> +
> +	memhp_range.start = 0;
> +	memhp_range.end =  VMEM_MAX_PHYS - 1;
> +	return memhp_range;
> +}
> +
>  int vmem_add_mapping(unsigned long start, unsigned long size)
>  {
> +	struct range range;
>  	int ret;
>  
> -	if (start + size > VMEM_MAX_PHYS ||
> +	range = arch_get_mappable_range();

You could do

struct range range = arch_get_mappable_range();

> +	if (start < range.start ||
> +	    start + size > range.end + 1 ||
>  	    start + size < start)
>  		return -ERANGE;
>  
> 


-- 
Thanks,

David / dhildenb