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Tue, 11 Nov 2025 19:40:08 -0800 (PST) Date: Wed, 12 Nov 2025 03:40:08 +0000 From: Wei Yang To: Lance Yang Cc: Wei Yang , linux-mm@kvack.org, baolin.wang@linux.alibaba.com, dev.jain@arm.com, Liam.Howlett@oracle.com, ryan.roberts@arm.com, npache@redhat.com, baohua@kernel.org, akpm@linux-foundation.org, david@kernel.org, lorenzo.stoakes@oracle.com, ziy@nvidia.com Subject: Re: [PATCH] mm/khugepaged: continue to collapse on SCAN_PMD_NONE Message-ID: <20251112034008.ojwghkko74psu65v@master> Reply-To: Wei Yang References: <20251112020031.25350-1-richard.weiyang@gmail.com> <06096f8b-4da0-4b5c-af3c-fd8871437c16@linux.dev> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <06096f8b-4da0-4b5c-af3c-fd8871437c16@linux.dev> User-Agent: NeoMutt/20170113 (1.7.2) X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: AB81310000C X-Stat-Signature: h7i11n5ucwgq4a34tjbkqag6jes1n6ai X-Rspam-User: X-HE-Tag: 1762918810-963634 X-HE-Meta: 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 Gwgg1gaU 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 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 Wed, Nov 12, 2025 at 10:37:06AM +0800, Lance Yang wrote: > > >On 2025/11/12 10:00, Wei Yang wrote: >> SCAN_PMD_NONE means current pmd is empty, but we can still continue >> collapse next pmd range. > >Right, bailing out of the whole MADV_COLLAPSE request just because >we encounter one empty PMD is too strict ... > >It makes sense to treat SCAN_PMD_NONE like the other whitelisted cases >(e.g., SCAN_PMD_NULL). >> >> Signed-off-by: Wei Yang >> --- > >LGTM. > >Reviewed-by: Lance Yang > Thanks for the review. I'm currently evaluating the use of SCAN_NULL versus SCAN_NONE. It seems their usage in the current code is intermixed, and I'm questioning if there's a strong, practical reason to maintain a distinction between these two states. Should they be unified? -- Wei Yang Help you, Help me