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b=blWZyuhnbETFn27f6OqpWrXth2ubBEfvedwLSFDNclPYXgtCbAhDrxvX4YbPzgnY4 GafPHFEqrHG3MGl+70esf4QkMiGaiHFMmDwXqV4rmExiGPGhuX/r8NIMkiujtvBNPR TWE4RtI14v78OTGKHAhyaTe0mIVCVIrDc+JhilPz/wSxNmJIFX+kUp+0D4jgXOPjus eQ3KbK9iKGOv6ywSd/6nTK44qZwWJTJ17MALEJpcGihTUP9TkcGMegy96fWkUKfkV6 EGJ6h5OFB0YhGJzJButnuR6EuXpSghAsJo0ezQXkb6sNsJDOa3EO39EqZpxOEzRc10 ed1wBFFsUQtMw== Message-ID: Date: Wed, 12 Nov 2025 10:51:43 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] mm/khugepaged: continue to collapse on SCAN_PMD_NONE From: "David Hildenbrand (Red Hat)" To: Wei Yang , 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 Cc: linux-mm@kvack.org References: <20251112020031.25350-1-richard.weiyang@gmail.com> <04e8e813-b43b-423e-8ad9-fb13ac953055@kernel.org> Content-Language: en-US In-Reply-To: <04e8e813-b43b-423e-8ad9-fb13ac953055@kernel.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 8732D100010 X-Stat-Signature: daf7799oit8agb78kh145sniuugzc3bg X-Rspam-User: X-HE-Tag: 1762941108-872275 X-HE-Meta: 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 HEiwDZyM V8u37qsjH1ZmWHefnn2YPSX10Q3IwpVf1dBkXX1qpktdGpnB96jZqr9YIBvVEXppS0ssfj+kQLkwfR9WOvnsB2By61xdAKCN0lxrFX6eBzp8VQJrZjU9Z6b4eqzSyW/kUZkPwuQHvzGYzuFeu3o8Hp1tx2Du4Me6miGBvMAA1aBO2PhUZfU8DpMONf6Venqld8xRvcIsZ/P7626ey79kzqlEJ9eexIpsPwk2z/Hz78WtyI/v28qJX/zvjg1tJS1/TYZWkUfGLY6Z0PuStjGBB0l3scFMCjHY5ynkUMzXN+5g+mCx6eNSorOnM82swCVdnICWSEwYfGic813wafU1uS6qwIy/9gGG+5jP9TkhEi5XFGfo= 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 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 -- Cheers David