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Wed, 18 Mar 2026 04:47:17 -0700 (PDT) Received: from gpc ([2400:8902:e002:ded5:78c1:8178:95c1:6ca3]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-82a6bf0cf5fsm3176671b3a.61.2026.03.18.04.47.10 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 18 Mar 2026 04:47:17 -0700 (PDT) From: WANG Rui To: usama.arif@linux.dev Cc: Liam.Howlett@oracle.com, ajd@linux.ibm.com, akpm@linux-foundation.org, anshuman.khandual@arm.com, apopple@nvidia.com, baohua@kernel.org, baolin.wang@linux.alibaba.com, brauner@kernel.org, catalin.marinas@arm.com, david@kernel.org, dev.jain@arm.com, hannes@cmpxchg.org, jack@suse.cz, kas@kernel.org, kees@kernel.org, kernel-team@meta.com, kevin.brodsky@arm.com, lance.yang@linux.dev, linux-arm-kernel@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, lorenzo.stoakes@oracle.com, npache@redhat.com, r@hev.cc, rmclure@linux.ibm.com, ryan.roberts@arm.com, shakeel.butt@linux.dev, viro@zeniv.linux.org.uk, will@kernel.org, willy@infradead.org, ziy@nvidia.com Subject: Re: [PATCH 0/4] arm64/mm: contpte-sized exec folios for 16K and 64K pages Date: Wed, 18 Mar 2026 19:46:53 +0800 Message-ID: <20260318114653.123656-1-r@hev.cc> X-Mailer: git-send-email 2.53.0 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 151B04000B X-Stat-Signature: zw1zcctmoows4n7wzya93mdj5196jmjc X-Rspam-User: X-HE-Tag: 1773834438-484897 X-HE-Meta: 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 7Jz4QtFE 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: > Thanks for running these! Just wanted to check what is the base page size > of this experiment? base page size: 4K > Yeah I think introducing Kconfig might be an option. I wonder if it would make sense for exec_folio_order() to vary the order based on the code size, instead of always returning a fixed value for a given architecture and base page size. For example, on AArch64 with 4K base pages, in the load_elf_binary() case: if exec_folio_order() only ever returns cont-PTE (64K), we may miss the opportunity to use PMD mappings. On the other hand, if it always returns PMD (2M), then for binaries smaller than 2M we end up reducing ASLR entropy. Maybe something along these lines would work better: unsigned int exec_folio_order(size_t code_size) { #if PAGE_SIZE == 4096 if (code_size >= PMD_SIZE) return ilog2(SZ_2M >> PAGE_SHIFT); else if (code_size >= SZ_64K) return ilog2(SZ_64K >> PAGE_SHIFT); else return 0; #elif PAGE_SIZE == 16384 ... #elif PAGE_SIZE == ... /* let the arch cap the max order here, rather than hard-coding it at the use sites */ #endif } Thanks, Rui