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Date:   Mon, 27 Jun 2022 18:31:39 +0530
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Subject: Re: [RFC PATCH 10/26] hugetlb: add for_each_hgm_shift
To:     James Houghton <jthoughton@google.com>,
        Mike Kravetz <mike.kravetz@oracle.com>,
        Muchun Song <songmuchun@bytedance.com>,
        Peter Xu <peterx@redhat.com>
Cc:     David Hildenbrand <david@redhat.com>,
        David Rientjes <rientjes@google.com>,
        Axel Rasmussen <axelrasmussen@google.com>,
        Mina Almasry <almasrymina@google.com>,
        Jue Wang <juew@google.com>,
        "Dr . David Alan Gilbert" <dgilbert@redhat.com>,
        linux-mm@kvack.org, linux-kernel@vger.kernel.org
References: <20220624173656.2033256-1-jthoughton@google.com>
 <20220624173656.2033256-11-jthoughton@google.com>
From:   "manish.mishra" <manish.mishra@nutanix.com>
In-Reply-To: <20220624173656.2033256-11-jthoughton@google.com>
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On 24/06/22 11:06 pm, James Houghton wrote:
> This is a helper macro to loop through all the usable page sizes for a
> high-granularity-enabled HugeTLB VMA. Given the VMA's hstate, it will
> loop, in descending order, through the page sizes that HugeTLB supports
> for this architecture; it always includes PAGE_SIZE.
reviewed-by:manish.mishra@nutanix.com
> Signed-off-by: James Houghton <jthoughton@google.com>
> ---
>   mm/hugetlb.c | 10 ++++++++++
>   1 file changed, 10 insertions(+)
>
> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> index 8b10b941458d..557b0afdb503 100644
> --- a/mm/hugetlb.c
> +++ b/mm/hugetlb.c
> @@ -6989,6 +6989,16 @@ bool hugetlb_hgm_enabled(struct vm_area_struct *vma)
>   	/* All shared VMAs have HGM enabled. */
>   	return vma->vm_flags & VM_SHARED;
>   }
> +static unsigned int __shift_for_hstate(struct hstate *h)
> +{
> +	if (h >= &hstates[hugetlb_max_hstate])
> +		return PAGE_SHIFT;
> +	return huge_page_shift(h);
> +}
> +#define for_each_hgm_shift(hstate, tmp_h, shift) \
> +	for ((tmp_h) = hstate; (shift) = __shift_for_hstate(tmp_h), \
> +			       (tmp_h) <= &hstates[hugetlb_max_hstate]; \
> +			       (tmp_h)++)
>   #endif /* CONFIG_HUGETLB_HIGH_GRANULARITY_MAPPING */
>   
>   /*