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[2003:d8:2f37:2b00:948c:dd9f:29c8:73f4]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-3d64ba4ff83sm5013587f8f.4.2025.09.01.06.43.44 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 01 Sep 2025 06:43:45 -0700 (PDT) Message-ID: Date: Mon, 1 Sep 2025 15:43:44 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC PATCH] mm: Enable khugepaged to operate on non-writable VMAs To: Kiryl Shutsemau Cc: Dev Jain , akpm@linux-foundation.org, willy@infradead.org, hughd@google.com, ziy@nvidia.com, baolin.wang@linux.alibaba.com, lorenzo.stoakes@oracle.com, Liam.Howlett@oracle.com, npache@redhat.com, ryan.roberts@arm.com, baohua@kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20250901074817.73012-1-dev.jain@arm.com> <7towtl2pjubgdil4csn5rg3usbai5xvzz73wqkwj5b5awh2iim@wfvahykzjrlo> <9c3a2ecd-ceae-4e87-a6d7-6a7121ab7a15@redhat.com> From: David Hildenbrand Content-Language: en-US Autocrypt: addr=david@redhat.com; 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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 01.09.25 15:15, Kiryl Shutsemau wrote: > On Mon, Sep 01, 2025 at 10:32:34AM +0200, David Hildenbrand wrote: >> >>>> @@ -676,9 +676,7 @@ static int __collapse_huge_page_isolate(struct vm_area_struct *vma, >>>> writable = true; >>>> } >>>> - if (unlikely(!writable)) { >>>> - result = SCAN_PAGE_RO; >>>> - } else if (unlikely(cc->is_khugepaged && !referenced)) { >>>> + if (unlikely(cc->is_khugepaged && !referenced)) { >>>> result = SCAN_LACK_REFERENCED_PAGE; >>>> } else { >>>> result = SCAN_SUCCEED; >>>> @@ -1421,9 +1419,7 @@ static int hpage_collapse_scan_pmd(struct mm_struct *mm, >>>> mmu_notifier_test_young(vma->vm_mm, _address))) >>>> referenced++; >>>> } >>>> - if (!writable) { >>>> - result = SCAN_PAGE_RO; >>>> - } else if (cc->is_khugepaged && >>>> + if (cc->is_khugepaged && >>> >>> The only practical use of the writable is gone. The only other usage is >>> tracing which can be dropped to as it is not actionable anymore. >>> >>> Could you drop writable? Maybe as a separate commit. >> >> I think we should just do it in the same patch. > > Change in trace_mm_collapse_huge_page_isolate() interface doesn't belong > to the same patch in my view. We frequently adjust tracing code (which is specific to khugepaged in this case) in the same patch. Anyhow, no strong opinion. -- Cheers David / dhildenb