Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Received-SPF: Pass (protection.outlook.com: domain of nvidia.com designates
 216.228.117.161 as permitted sender) receiver=protection.outlook.com;
 client-ip=216.228.117.161; helo=mail.nvidia.com; pr=C
Message-ID: <e1f40f3f-162e-7d3c-00f1-8c71e3b5dc31@nvidia.com>
Date:   Wed, 7 Dec 2022 13:21:12 -0800
MIME-Version: 1.0
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101
 Thunderbird/102.5.1
Subject: Re: [PATCH v2 01/10] mm/hugetlb: Let vma_offset_start() to return
 start
Content-Language: en-US
To:     Peter Xu <peterx@redhat.com>, <linux-mm@kvack.org>,
        <linux-kernel@vger.kernel.org>
CC:     Muchun Song <songmuchun@bytedance.com>,
        Andrea Arcangeli <aarcange@redhat.com>,
        James Houghton <jthoughton@google.com>,
        Jann Horn <jannh@google.com>, Rik van Riel <riel@surriel.com>,
        Miaohe Lin <linmiaohe@huawei.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        "Mike Kravetz" <mike.kravetz@oracle.com>,
        David Hildenbrand <david@redhat.com>,
        Nadav Amit <nadav.amit@gmail.com>
References: <20221207203034.650899-1-peterx@redhat.com>
 <20221207203034.650899-2-peterx@redhat.com>
From:   John Hubbard <jhubbard@nvidia.com>
In-Reply-To: <20221207203034.650899-2-peterx@redhat.com>
Content-Type: text/plain; charset="UTF-8"; format=flowed
Content-Transfer-Encoding: 7bit
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 07 Dec 2022 21:21:24.1970
 (UTC)
X-MS-Exchange-CrossTenant-Network-Message-Id: 2d393121-a19d-4f8d-8a73-08dad898fe8b
X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a
X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=43083d15-7273-40c1-b7db-39efd9ccc17a;Ip=[216.228.117.161];Helo=[mail.nvidia.com]
X-MS-Exchange-CrossTenant-AuthSource: DS1PEPF0000E659.namprd02.prod.outlook.com
X-MS-Exchange-CrossTenant-AuthAs: Anonymous
X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem
X-MS-Exchange-Transport-CrossTenantHeadersStamped: PH0PR12MB8031
X-Spam-Status: No, score=-1.4 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH,
        DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,FORGED_SPF_HELO,
        NICE_REPLY_A,RCVD_IN_DNSWL_NONE,RCVD_IN_MSPIKE_H2,SPF_HELO_PASS,
        SPF_NONE autolearn=no autolearn_force=no version=3.4.6
X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on
        lindbergh.monkeyblade.net
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On 12/7/22 12:30, Peter Xu wrote:
> Even though vma_offset_start() is named like that, it's not returning "the
> start address of the range" but rather the offset we should use to offset
> the vma->vm_start address.
> 
> Make it return the real value of the start vaddr, and it also helps for all
> the callers because whenever the retval is used, it'll be ultimately added
> into the vma->vm_start anyway, so it's better.
> 
> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
> Reviewed-by: David Hildenbrand <david@redhat.com>
> Signed-off-by: Peter Xu <peterx@redhat.com>
> ---
>   fs/hugetlbfs/inode.c | 24 ++++++++++++------------
>   1 file changed, 12 insertions(+), 12 deletions(-)

This is a nice refinement.

Reviewed-by: John Hubbard <jhubbard@nvidia.com>


thanks,
-- 
John Hubbard
NVIDIA

> 
> diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c
> index 790d2727141a..fdb16246f46e 100644
> --- a/fs/hugetlbfs/inode.c
> +++ b/fs/hugetlbfs/inode.c
> @@ -412,10 +412,12 @@ static bool hugetlb_vma_maps_page(struct vm_area_struct *vma,
>    */
>   static unsigned long vma_offset_start(struct vm_area_struct *vma, pgoff_t start)
>   {
> +	unsigned long offset = 0;
> +
>   	if (vma->vm_pgoff < start)
> -		return (start - vma->vm_pgoff) << PAGE_SHIFT;
> -	else
> -		return 0;
> +		offset = (start - vma->vm_pgoff) << PAGE_SHIFT;
> +
> +	return vma->vm_start + offset;
>   }
>   
>   static unsigned long vma_offset_end(struct vm_area_struct *vma, pgoff_t end)
> @@ -457,7 +459,7 @@ static void hugetlb_unmap_file_folio(struct hstate *h,
>   		v_start = vma_offset_start(vma, start);
>   		v_end = vma_offset_end(vma, end);
>   
> -		if (!hugetlb_vma_maps_page(vma, vma->vm_start + v_start, page))
> +		if (!hugetlb_vma_maps_page(vma, v_start, page))
>   			continue;
>   
>   		if (!hugetlb_vma_trylock_write(vma)) {
> @@ -473,8 +475,8 @@ static void hugetlb_unmap_file_folio(struct hstate *h,
>   			break;
>   		}
>   
> -		unmap_hugepage_range(vma, vma->vm_start + v_start, v_end,
> -				NULL, ZAP_FLAG_DROP_MARKER);
> +		unmap_hugepage_range(vma, v_start, v_end, NULL,
> +				     ZAP_FLAG_DROP_MARKER);
>   		hugetlb_vma_unlock_write(vma);
>   	}
>   
> @@ -507,10 +509,9 @@ static void hugetlb_unmap_file_folio(struct hstate *h,
>   		 */
>   		v_start = vma_offset_start(vma, start);
>   		v_end = vma_offset_end(vma, end);
> -		if (hugetlb_vma_maps_page(vma, vma->vm_start + v_start, page))
> -			unmap_hugepage_range(vma, vma->vm_start + v_start,
> -						v_end, NULL,
> -						ZAP_FLAG_DROP_MARKER);
> +		if (hugetlb_vma_maps_page(vma, v_start, page))
> +			unmap_hugepage_range(vma, v_start, v_end, NULL,
> +					     ZAP_FLAG_DROP_MARKER);
>   
>   		kref_put(&vma_lock->refs, hugetlb_vma_lock_release);
>   		hugetlb_vma_unlock_write(vma);
> @@ -540,8 +541,7 @@ hugetlb_vmdelete_list(struct rb_root_cached *root, pgoff_t start, pgoff_t end,
>   		v_start = vma_offset_start(vma, start);
>   		v_end = vma_offset_end(vma, end);
>   
> -		unmap_hugepage_range(vma, vma->vm_start + v_start, v_end,
> -				     NULL, zap_flags);
> +		unmap_hugepage_range(vma, v_start, v_end, NULL, zap_flags);
>   
>   		/*
>   		 * Note that vma lock only exists for shared/non-private