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b=V50cSsvgX5TzA7qHWhwRyQKwLZenq97Ek5BWphCnh5KEKL4Ij5XcrwVLyPvuVz1w8 ZLzEPjYlNXzqH/8D/gH19704pySpJKM+2DLh+f9gmn/AsYOPWVgy7NuxKc4i3CmEyD B3dBdnDKQp2l2X6kqFBmNSOMEbuBpXfn9KfzYZuJexQL+l253CPBFI73/1+vLIFz3a EHRAgFz9lPu2FtfV1VvFwITZddbpKhtJyOqQPAu9JMDnu7VAdbJSS2Pkr8oBbD7YDP hFbi3M/gHXBVAb1IckloaeDog/qYIF8ZCctyNLOWy/LL4xjvolhscUx4GmFdOL1LzR 2PqDQTuPSxBew== Message-ID: <374276d0-1831-44dc-b7c8-1976a07da296@kernel.org> Date: Wed, 12 Nov 2025 12:41:12 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] mm/khugepaged: continue to collapse on SCAN_PMD_NONE To: Wei Yang Cc: akpm@linux-foundation.org, lorenzo.stoakes@oracle.com, ziy@nvidia.com, baolin.wang@linux.alibaba.com, Liam.Howlett@oracle.com, npache@redhat.com, ryan.roberts@arm.com, dev.jain@arm.com, baohua@kernel.org, lance.yang@linux.dev, linux-mm@kvack.org References: <20251112020031.25350-1-richard.weiyang@gmail.com> <04e8e813-b43b-423e-8ad9-fb13ac953055@kernel.org> <20251112112739.ovfkj6zy7kqcervv@master> From: "David Hildenbrand (Red Hat)" Content-Language: en-US In-Reply-To: <20251112112739.ovfkj6zy7kqcervv@master> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: A0D641C0008 X-Stat-Signature: hc3rejh443kkugmko9us64bq7367xfxf X-Rspam-User: X-HE-Tag: 1762947677-637807 X-HE-Meta: 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 9YWxjw/C DGnHul8iRKEPk/apXiZiHmlEGBXY6Rw3WVDpxE7VH7vVF8Xtqhgtc0Z/EMELTuT1mARcsex/AU3dRTOlOrznMZOowL1iqbTak8LQ3UiKiIqy8ZRN42F5wJoM3S1/dZRnOgU0c/L4HrIZTZS6O9RegGB7Nux6duNyIIgk/RC/cJvUc3fvIgvsN1a0fzyVgt4FiD45cVCODH6w9sVb5SvZN4yOKA3uZs7F7a4U4wkEi0wuSnWPZv/MVTEqLGcOEO6V+VdnTyoX8qu02YjtMIb5d31F6oGzvLuuuetMm37iOolxB2lrqYJZdqimDip3l7+H8Z87ixfpcaTGw47UlMxJ0sioOilHbTf4AfYOfRCEOeH40XB0= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 12.11.25 12:27, Wei Yang wrote: > On Wed, Nov 12, 2025 at 10:51:43AM +0100, David Hildenbrand (Red Hat) wrote: >> On 12.11.25 10:51, David Hildenbrand (Red Hat) wrote: >>> On 12.11.25 03:00, Wei Yang wrote: >>>> SCAN_PMD_NONE means current pmd is empty, but we can still continue >>>> collapse next pmd range. >>>> >>>> Signed-off-by: Wei Yang >>>> --- >>>> mm/khugepaged.c | 1 + >>>> 1 file changed, 1 insertion(+) >>>> >>>> diff --git a/mm/khugepaged.c b/mm/khugepaged.c >>>> index 7e8cb181d5bd..4c2217076ad3 100644 >>>> --- a/mm/khugepaged.c >>>> +++ b/mm/khugepaged.c >>>> @@ -2835,6 +2835,7 @@ int madvise_collapse(struct vm_area_struct *vma, unsigned long start, >>>> goto handle_result; >>>> /* Whitelisted set of results where continuing OK */ >>>> case SCAN_PMD_NULL: >>>> + case SCAN_PMD_NONE: >>>> case SCAN_PTE_NON_PRESENT: >>>> case SCAN_PTE_UFFD_WP: >>>> case SCAN_LACK_REFERENCED_PAGE: >>> >>> Looks ok to me. >>> >>> I am really confused about PMD_NONE vs. PMD_NULL. >>> >>> Is my understanding correct, hat with your patch we can just merge both >>> into a single NO_PMD_TABLE or sth. like that? >> >> NO_PTE_TABLE, actually >> > > I am thinking about this too. > > If no other objections, I will prepare a v2 with this. > > BTW, you prefer merge them directly, or merge on top of this change? I'd probably do it in a single commit, stating that both scenarios should be handled completely the same. But no strong opinion against doing it in two commits from my side. -- Cheers David