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Wed, 13 May 2026 06:11:44 -0700 (PDT) From: Muchun Song To: Andrew Morton , David Hildenbrand , Muchun Song , Oscar Salvador , Michael Ellerman , Madhavan Srinivasan Cc: Lorenzo Stoakes , "Liam R . Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Nicholas Piggin , Christophe Leroy , Ackerley Tng , Frank van der Linden , aneesh.kumar@linux.ibm.com, joao.m.martins@oracle.com, linux-mm@kvack.org, linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, Muchun Song Subject: [PATCH v2 46/69] mm/sparse-vmemmap: Map shared vmemmap tail pages read-only Date: Wed, 13 May 2026 21:05:14 +0800 Message-ID: <20260513130542.35604-47-songmuchun@bytedance.com> X-Mailer: git-send-email 2.50.1 In-Reply-To: <20260513130542.35604-1-songmuchun@bytedance.com> References: <20260513130542.35604-1-songmuchun@bytedance.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 6AE82140003 X-Stat-Signature: xr9iemhjhi7d4ebzq4wgt94jxuhrg8k4 X-Rspam-User: X-HE-Tag: 1778677907-536889 X-HE-Meta: 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 tZAp2SBu i9Qg/a4gkR8e6v6dJsJ9H5Sa9vwMY0W8Ci5loAipzFjXVU8tNQU5ilFdS5fmuDEyOkljuKJ5nDQQC1TdXfoP65A2/CCarnC1EHXGHjU1/yjSXI0jU2S02YqmS5ODg3dwgsd5OnapELKMSLFgX9OT4U6QfK3zWxYx4t3u1JDW6CO4aRGo3YTJOxgBhQWSqd1qZqRldfoFuhuHG3xapIgdeEDuNuEPd6OTqgUpcoDn0C9UVDRDmb68RcLsuXljplDbA86N1MKIwUqHA68KSdEow6Ub1d2uN2MAX2fvZ+iYEO+O+3TzfXy4n2f69Fg== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Shared vmemmap tail pages are now installed through vmemmap_pte_populate(). Map those shared pages with PAGE_KERNEL_RO so writes to shared tail vmemmap entries fault immediately instead of silently corrupting shared metadata. Signed-off-by: Muchun Song --- mm/sparse-vmemmap.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/mm/sparse-vmemmap.c b/mm/sparse-vmemmap.c index 182d0c7dd1e7..9811c92ad258 100644 --- a/mm/sparse-vmemmap.c +++ b/mm/sparse-vmemmap.c @@ -158,7 +158,8 @@ static pte_t * __meminit vmemmap_pte_populate(pmd_t *pmd, unsigned long addr, in if (slab_is_available()) get_page(page); - entry = pfn_pte(page_to_pfn(page), PAGE_KERNEL); + /* Map shared tail page read-only to catch illegal writes. */ + entry = pfn_pte(page_to_pfn(page), PAGE_KERNEL_RO); } else { void *vaddr = vmemmap_alloc_block_buf(PAGE_SIZE, node, altmap); -- 2.54.0