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b=O27aeL/A2mRiLDoNKzrDT1uVXrflSw3am10n700SW41y6hC+GG5MGlriX6dfzn4Fg Jxit3FTVr8Kbzew+hraP42StynheUxDySfg0VcS6c/x9S4Jnw9ikSQN2EFh5H5bnlm gkfuB2nvqoUWAHdJyVt+VpKOpbbp7gBoPQMuInJQL6uX8GKE6gWQi1W1cVMdTYsXXQ K+Uhnkf+7Usv1EXOPi9VorJ/tdeAM6XBQbF3PwGnnssjdEj2qevxVa3B9TW1/IyIFR hy7d24L6EKK4M07DeudSftjs+uIqJfswJH8C+bPdy2M49j38/w+Tq33cAlJbq6bTlx Zv3SmbIMSDWgA== Message-ID: <664510b2-3510-499f-aab5-ceddfcc82581@kernel.org> Date: Fri, 9 Oct 2026 22:37:28 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 2/4] riscv/mm: fix hotplug page-table destructor handling To: Muchun Song , akpm@linux-foundation.org Cc: linux-mm@kvack.org, stable@vger.kernel.org, osalvador@suse.de, dave.hansen@linux.intel.com, luto@kernel.org, peterz@infradead.org, tglx@kernel.org, mingo@redhat.com, bp@alien8.de, x86@kernel.org, hpa@zytor.com, catalin.marinas@arm.com, will@kernel.org, mark.rutland@arm.com, linux-arm-kernel@lists.infradead.org, pjw@kernel.org, palmer@dabbelt.com, aou@eecs.berkeley.edu, alex@ghiti.fr, linux-riscv@lists.infradead.org, agordeev@linux.ibm.com, kevin.brodsky@arm.com, bjorn@rivosinc.com, apopple@nvidia.com, linux-kernel@vger.kernel.org, muchun.song@linux.dev References: <20261008073021.2512665-1-songmuchun@bytedance.com> <20261008073021.2512665-3-songmuchun@bytedance.com> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: DB1CF180002 X-Stat-Signature: rodwpdqr7pe4x145unexi5p969s3iuxc X-HE-Tag: 1791578259-954325 X-HE-Meta: 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 Y3F+LEYD MFNeuEnLOzOJMHh/KZn/qASUeXq7nPmD6gfthXtrsgvf7ahPf5wJfkwANrw1XmMaR1dpvPBDKBN5gLT9/XOaJUDv9Qub4ZiULLjHh5etr/Yf4nLyR6HMRwphjhMvd5cFdnNj8iOcKh5FcUmqOT6M3XFAYOLK+dUWcyDu5CuT+4BexN48lXOfX6mFxIwHmqOHu6p8hBlisM1oeKlFAUx285tMgtgUSsQMoBheR8gfVUJx5MKKz3KGHi/x1Cx+h5IlPcj8Qh4pbyQNWZvYJ/ul4af+hoUX4QRytz84I3gbFMqGvPSC5/ICjErtxlA== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 10/8/26 09:30, Muchun Song wrote: > RISC-V uses the same memory-hotplug teardown code for the linear map and > vmemmap, although their page-table pages are not always allocated in the > same way. Late linear-map allocations run page-table constructors, while > vmemmap and early allocations may provide constructor-free pages. > > The PTE path unconditionally runs the destructor, which is wrong for > constructor-free vmemmap tables. The PMD path avoids that problem by > using is_vmemmap as a proxy for constructor state, but that assumption > will no longer hold once runtime vmemmap allocations use the normal > pgalloc helpers. > > Page-table constructors record their state in PG_table. Centralize > page-table freeing and use PageTable() to decide whether the destructor > is required. Keep reserved and constructor-free pages on their existing > freeing paths. > > Fixes: c75a74f4ba19 ("riscv: mm: Add memory hotplugging support") > Cc: stable@vger.kernel.org > Assisted-by: LLM > Signed-off-by: Muchun Song > --- > arch/riscv/mm/init.c | 29 ++++++++++++++--------------- > 1 file changed, 14 insertions(+), 15 deletions(-) > > diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c > index 857f9a55039c..429a0b015ec1 100644 > --- a/arch/riscv/mm/init.c > +++ b/arch/riscv/mm/init.c > @@ -1486,10 +1486,19 @@ struct execmem_info __init *execmem_arch_setup(void) > #endif /* CONFIG_EXECMEM */ > > #ifdef CONFIG_MEMORY_HOTPLUG > +static void __meminit free_pagetable(struct page *page) > +{ > + if (PageReserved(page)) > + free_reserved_page(page); > + else if (PageTable(page)) > + pagetable_dtor_free(page_ptdesc(page)); > + else > + pagetable_free(page_ptdesc(page)); Similar thought, can't we detect that in pagetable_free() somehow and avoid requiring callers to handle that? -- Cheers, David