Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Subject: Re: [PATCHv3, RESEND 8/8] khugepaged: Introduce 'max_ptes_shared'
 tunable
To:     "Kirill A. Shutemov" <kirill@shutemov.name>
Cc:     "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
        akpm@linux-foundation.org, Andrea Arcangeli <aarcange@redhat.com>,
        Zi Yan <ziy@nvidia.com>, Ralph Campbell <rcampbell@nvidia.com>,
        John Hubbard <jhubbard@nvidia.com>,
        William Kucharski <william.kucharski@oracle.com>,
        linux-mm@kvack.org, linux-kernel@vger.kernel.org
References: <20200413125220.663-1-kirill.shutemov@linux.intel.com>
 <20200413125220.663-9-kirill.shutemov@linux.intel.com>
 <fcbfabac-1837-a4ea-1333-15445587e9fd@linux.alibaba.com>
 <20200416155206.bqpd5p45oud4chg6@box>
From:   Yang Shi <yang.shi@linux.alibaba.com>
Message-ID: <33a19097-5b4f-ea6e-6d6e-3ccda56607f5@linux.alibaba.com>
Date:   Thu, 16 Apr 2020 11:25:56 -0700
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.12; rv:52.0)
 Gecko/20100101 Thunderbird/52.7.0
MIME-Version: 1.0
In-Reply-To: <20200416155206.bqpd5p45oud4chg6@box>
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Transfer-Encoding: 7bit
Content-Language: en-US
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk


On 4/16/20 8:52 AM, Kirill A. Shutemov wrote:
> On Wed, Apr 15, 2020 at 02:25:30PM -0700, Yang Shi wrote:
>>> @@ -595,6 +626,12 @@ static int __collapse_huge_page_isolate(struct vm_area_struct *vma,
>>>    		VM_BUG_ON_PAGE(!PageAnon(page), page);
>>> +		if (page_mapcount(page) > 1 &&
>>> +				++shared > khugepaged_max_ptes_shared) {
>>> +			result = SCAN_EXCEED_SHARED_PTE;
>> It may be better to extract the check into a helper? For example, bool
>> exceed_max_ptes_shared(struct page)?
> It might be reasonable as part of wider cleanup: the same has to be done
> to khugepaged_max_ptes_none and khugepaged_max_ptes_swap.
>
> Volunteers? :P

Fine, I will take it. :-)

>