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From: Muchun Song In-Reply-To: Date: Mon, 1 Jun 2026 20:37:42 +0800 Cc: Muchun Song , Andrew Morton , Catalin Marinas , Will Deacon , Palmer Dabbelt , Paul Walmsley , Huacai Chen , Andreas Larsson , "David S. Miller" , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-riscv@lists.infradead.org, loongarch@lists.linux.dev, sparclinux@vger.kernel.org, Alexandre Ghiti , Albert Ou , WANG Xuerui , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko Content-Transfer-Encoding: quoted-printable Message-Id: <0D4AF42F-37C5-4A76-9703-44ACC6374C48@linux.dev> References: <20260601084845.3792171-1-songmuchun@bytedance.com> <20260601084845.3792171-2-songmuchun@bytedance.com> To: "David Hildenbrand (Arm)" X-Migadu-Flow: FLOW_OUT X-Stat-Signature: d3eid6qqsgpjjrh5qwz9ze6wt9d8h5q8 X-Rspamd-Queue-Id: 85BEA18000C X-Rspam-User: X-Rspamd-Server: rspam10 X-HE-Tag: 1780317518-556446 X-HE-Meta: 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 ZMWiklxB cCwj/30DKhE0vG6CiA7N+JuWmPClLseaAJ8F5IY71nkqrJOV5P+cgingn0Gs7sPi2nQT9mqpGgGelRfuJ2xXJFyUD88h5hvkOWnPCkvesJKoOycvJu4MrZf3plVm7MMl1WM2ttm86myicq6OCIXrmo8s/y4ikJ2GWTEABwqR6W/L94y9ZzZRIXcfpo2foziGrdSbiAZiF2RklUwkoFkDtiLcaSl8nv6JeTfgGXUFNTK7jG4KnBM8gP/TH5/b3VGx6fIu8F8hXwQZ8HSPFASNw+0gKru+q/hdKw7KY0CLPrYW1P9w+7jsP1SrHVkRt0w+Vmu2X/IdK8umLrVw= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: > On Jun 1, 2026, at 20:22, David Hildenbrand (Arm) = wrote: >=20 > On 6/1/26 10:48, Muchun Song wrote: >> The two weak functions are currently no-ops on every architecture, >> forcing each platform that needs them to duplicate the same handful >> of lines. Provide a generic implementation: >>=20 >> - vmemmap_set_pmd() simply sets a huge PMD with PAGE_KERNEL = protection. >>=20 >> - vmemmap_check_pmd() verifies that the PMD is present and leaf, >> then calls the existing vmemmap_verify() helper. >>=20 >> Architectures that need special handling can continue to override the >> weak symbols; everyone else gets the standard version for free. >>=20 >> Signed-off-by: Muchun Song >> --- >> v2->v3: >> - Replace BUG_ON() with WARN_ON_ONCE() in vmemmap_set_pmd() >> --- >> mm/sparse-vmemmap.c | 7 ++++++- >> 1 file changed, 6 insertions(+), 1 deletion(-) >>=20 >> diff --git a/mm/sparse-vmemmap.c b/mm/sparse-vmemmap.c >> index 112ccf9c71ca..99e2be39671b 100644 >> --- a/mm/sparse-vmemmap.c >> +++ b/mm/sparse-vmemmap.c >> @@ -386,12 +386,17 @@ int __meminit vmemmap_populate_hvo(unsigned = long addr, unsigned long end, >> void __weak __meminit vmemmap_set_pmd(pmd_t *pmd, void *p, int node, >> unsigned long addr, unsigned long next) >> { >> + WARN_ON_ONCE(!pmd_set_huge(pmd, virt_to_phys(p), PAGE_KERNEL)); >=20 >=20 > Not sure if a VM_WARN_ON_ONCE() would be appropriate. (then, we have = to move the > pmd_set_huge() out of the statement). I think it might be better to keep WARN_ON_ONCE here. This way, we can = still monitor for warnings in production while keeping the code simple. >=20 > Acked-by: David Hildenbrand (Arm) Thanks. >=20 >=20 > --=20 > Cheers, >=20 > David