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b=mR5547fpKxCJf0XlTdI9xDkvs66R5fMpuoyFGy3sz+isEcGZKY/mYsjmZY6KBlkKm S12vTHBxWqDDRaeNVwQikJkA9snuJhlZ2zE5KPbrnDnnWOa6XgIzEP/iDb6eSk13qT WBnHDbMvAtHGtyoMHkjDwtmN3ffUNad1alOJNuakUnY0oklWGAfP3lZ3gU89Gqoil2 wk9hpuBDLrtpHOKqX6Y/hI2pvcBDK/YO2F8tIICTaYojkQwOLVNGOOtSdldwj/ThuG XeHRaU8sm5kKPCrlZnPatsIEaaraxxDzznOaCIQ0cyBpyjnhzEfQk3NtiF71zvYj7f HaogrdbefYn0A== Date: Tue, 2 Jun 2026 14:12:17 +0100 From: Will Deacon To: Andrew Morton Cc: Catalin Marinas , Alistair Popple , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, david@kernel.org, kevin.brodsky@arm.com Subject: Re: [PATCH] arm64: mm: call pagetable dtor when freeing hot-removed page tables Message-ID: References: <20260521032730.2104017-1-apopple@nvidia.com> <20260521153130.d7d5cd060f7522f894252333@linux-foundation.org> <20260601212225.11f277a85d5ed15083b08cc2@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260601212225.11f277a85d5ed15083b08cc2@linux-foundation.org> X-Rspamd-Queue-Id: 9FF8B100011 X-Rspam-User: X-Stat-Signature: 3k8guy6os1y4cmoxxfimdwmwmue7wpos X-Rspamd-Server: rspam09 X-HE-Tag: 1780405943-836556 X-HE-Meta: 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 6dQGtoU4 5O7ptojME6fTqr0MTBtW4fswQRLxHXurb+a8i5WhCBd1qkx3SQkqtTovwWMz4whLCp3brJT+hhMkP767TNKOmVmjexKnfsBupGzJ0nmNUvohSHY/oBXij1xug2tjla953E7b6aff4NzqffQ/dLH6SaF12Km3ikYThq8z16jpJUWdK8nQGSPzdD+wgvXMROHafRHPbDmwyolDVIDvCUQLnFUTHBTCYSmg+4LdQXwrPbFT4LK64b3jKHJrJ8+3xspvmN7YsNPP+TWX0J19ktSIu90bPrJYC3ylpgGl12eEes0YZt8D1VRhc3niav46H8midiLztecIN4+IkApNbi+rgDuVuPZauzJDQaL9641wTOlAWDLc1JC2OzT4FjJgt/kbIPcflZClyLsrnYVk= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, Jun 01, 2026 at 09:22:25PM -0700, Andrew Morton wrote: > On Fri, 22 May 2026 08:15:09 +0100 Catalin Marinas wrote: > > > > > --- a/arch/arm64/mm/mmu.c > > > > +++ b/arch/arm64/mm/mmu.c > > > > @@ -1422,6 +1422,7 @@ static void free_hotplug_page_range(struct page *page, size_t size, > > > > > > > > static void free_hotplug_pgtable_page(struct page *page) > > > > { > > > > + pagetable_dtor(page_ptdesc(page)); > > > > free_hotplug_page_range(page, PAGE_SIZE, NULL); > > > > } > > > > > > I'd of course prefer that arm maintainers handle this. But > > > 5e8eb9aeeda3 came via myself so convention kinda-dictates that I get to > > > fix it. > > > > That's fine but Sashiko has some points: > > > > https://sashiko.dev/#/patchset/20260521032730.2104017-1-apopple@nvidia.com > > > > The __remove_pgd_mapping() path is fine but we also have the > > vmemmap_free() path where the constructor was never called. > > > > We could pass around a bool dtor argument but I wonder whether we could > > just check it's a pgtable page: > > > > diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c > > index 4c8959153ac4..9d42cbddce27 100644 > > --- a/arch/arm64/mm/mmu.c > > +++ b/arch/arm64/mm/mmu.c > > @@ -1441,6 +1441,9 @@ static void free_hotplug_page_range(struct page *page, size_t size, > > > > static void free_hotplug_pgtable_page(struct page *page) > > { > > + if (folio_test_pgtable(page_folio(page))) > > + pagetable_dtor(page_ptdesc(page)); > > + > > free_hotplug_page_range(page, PAGE_SIZE, NULL); > > } > > This patch is still floating around in mm.git awaiting some > finalization. What to do? >From what I can tell (assuming I've been following along correctly!): 1. This patch improves the situation, so makes sense in its own right 2. There is additional work to be more consistent with the constructors for page-table pages, which Kevin is going to look at but is probably a little more long-term. 3. I'm happy to take this via arm64 but also have no issues with you taking it via mm (so please shout if you want me to pick it up). Will