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b=HWkN5KrlKIk6OWt38SO9fMGwArGXNLm8Sc0PCX7ZgeMYOylWuJpHNU8t2FYDltQLn 2hKVTP6VzNHCqHXVINEqZTs/LUesNwkJVsuSfNVRWiSG6EM+asdu7XUYpBPEPDbhyg xxL2L457nAJjsnW9ul382bkmFZlkcJ0BfutYNMatFDZqAAKt4pPj7uICuTiy4ojVEP ugz5q4KFQCUm7kDaKATbRD/9S7WIDuKfPfrxc0hLnTMVOL+lI7sBSP7t1MeAxfaysa lqZ9eoh+QQZamGuMRiYovi7Gku403d6K2cuOnrn5lClA+St/Yv/3lziXSu4nT82KA4 ZsIxQ2m9QprXw== From: =?utf-8?B?QmrDtnJuIFTDtnBlbA==?= To: Muchun Song , akpm@linux-foundation.org Cc: linux-mm@kvack.org, stable@vger.kernel.org, david@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 Subject: Re: [PATCH 2/4] riscv/mm: fix hotplug page-table destructor handling In-Reply-To: <20261008073021.2512665-3-songmuchun@bytedance.com> References: <20261008073021.2512665-1-songmuchun@bytedance.com> <20261008073021.2512665-3-songmuchun@bytedance.com> Date: Fri, 09 Oct 2026 08:09:31 +0200 Message-ID: <87jynrs8v8.fsf@all.your.base.are.belong.to.us> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 4165020004 X-Rspam-User: X-Stat-Signature: ukmpcfqmwmeysoumbxesx84idwu7dmrn X-HE-Tag: 1791526176-964676 X-HE-Meta: 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 Jd5lhJv5 CQpOn2tK3et15J2M1sSqEIefehS/4tzW/3jG+qBpOGW9A2PVwkK326XC0J+LHLzp4IpxxKYtHFwXfhNOCEi2m7HvOUvx5yVFNuWrwUDXdgx54/n2yxxH1aaI5y5fHGjkN0pmD3pbCz73yDn8Jy3uT20/SXJm7FpKKi1d3kd8aNZaHwoJYomKb5WA5zvZM0RBGSYuMVaGoMeN0EAtkK2C4u846Ivlh+YSX2EtGp9SDAIfaeBNf+kMJTKTtJRCMRTrHCq5QYk0w7C9UuIA+dn27lZBKts0efvCoLfBZGcQ247Gn/kHCxwQUK+BrG9L6OWiKtvayHtrRwld6XLI= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Muchun Song writes: > 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(vo= id) > #endif /* CONFIG_EXECMEM */ >=20=20 > #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)); > +} Is PageReserved() enought to determine if there's no dtor to run? On rv64 your code is correct, but maybe for robustness? | if (PageTable(page)) | pagetable_dtor(page_ptdesc(page)); |=20 | if (PageReserved(page)) | free_reserved_page(page); | else | pagetable_free(page_ptdesc(page)); Bj=C3=B6rn