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Sat, 04 Oct 2025 02:42:18 -0700 (PDT) Date: Sat, 4 Oct 2025 09:42:17 +0000 From: Wei Yang To: Dev Jain Cc: Lance Yang , akpm@linux-foundation.org, david@redhat.com, lorenzo.stoakes@oracle.com, ziy@nvidia.com, baolin.wang@linux.alibaba.com, Liam.Howlett@oracle.com, npache@redhat.com, ryan.roberts@arm.com, baohua@kernel.org, ioworker0@gmail.com, richard.weiyang@gmail.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH mm-new 2/2] mm/khugepaged: merge PTE scanning logic into a new helper Message-ID: <20251004094217.bah5q2zxczrqontm@master> Reply-To: Wei Yang References: <20251002073255.14867-1-lance.yang@linux.dev> <20251002073255.14867-3-lance.yang@linux.dev> <0d55d763-81ff-4b99-bb13-3dbb9af53cdc@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <0d55d763-81ff-4b99-bb13-3dbb9af53cdc@arm.com> User-Agent: NeoMutt/20170113 (1.7.2) X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 5F0FD120002 X-Stat-Signature: q9mfb7dsqshap1mieptdgwrwdysc4zf3 X-Rspam-User: X-HE-Tag: 1759570940-739761 X-HE-Meta: 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 b3yFDLUk 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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 Fri, Oct 03, 2025 at 10:35:12PM +0530, Dev Jain wrote: > >On 02/10/25 1:02 pm, Lance Yang wrote: >> From: Lance Yang >> >> As David suggested, the PTE scanning logic in hpage_collapse_scan_pmd() >> and __collapse_huge_page_isolate() was almost duplicated. >> >> This patch cleans things up by moving all the common PTE checking logic >> into a new shared helper, thp_collapse_check_pte(). >> >> Suggested-by: David Hildenbrand >> Signed-off-by: Lance Yang >> --- > >In hpage_collapse_scan_pmd(), we enter with mmap lock held, so for This is true for the first loop, but we will unlock/lock mmap and revalidate vma before isolation. >an anonymous vma, is it even possible to hit if (!folio_test_anon(folio))? >In which case we can replace this with VM_BUG_ON_FOLIO and abstract away >till the folio_maybe_mapped_shared() block? But it looks still valid, since hugepage_vma_revalidate() will check the vma is still anonymous vma after grab the mmap lock again. My concern is would VM_BUG_ON_FOLIO() be too heavy? How about warn on and return? -- Wei Yang Help you, Help me