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DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1773154479; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=EGWvFNNHbAVQyTUs3YvCDY0GyMiml7VfROhcweab0g8=; b=taHmAdo34oCwjQFIaRdmRojINXQm081BWLVpiG89JRPghIcpldJ2rwOWU0KURRrhy5yjpf 19sWjb7mkMYRCePOGCQXpG9Wc5IKYu1fi/V6HuLIH/qnuv0qdwjurQ0tE2yqYewmgWxhBS i69FLwkpsJPKnJP2wwNrpkeBXTBIoAo= From: Usama Arif To: Andrew Morton , ryan.roberts@arm.com, david@kernel.org Cc: ajd@linux.ibm.com, anshuman.khandual@arm.com, apopple@nvidia.com, baohua@kernel.org, baolin.wang@linux.alibaba.com, brauner@kernel.org, catalin.marinas@arm.com, dev.jain@arm.com, jack@suse.cz, kees@kernel.org, kevin.brodsky@arm.com, lance.yang@linux.dev, Liam.Howlett@oracle.com, 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, rmclure@linux.ibm.com, Al Viro , will@kernel.org, willy@infradead.org, ziy@nvidia.com, hannes@cmpxchg.org, kas@kernel.org, shakeel.butt@linux.dev, kernel-team@meta.com, Usama Arif Subject: [PATCH 1/4] arm64: request contpte-sized folios for exec memory Date: Tue, 10 Mar 2026 07:51:14 -0700 Message-ID: <20260310145406.3073394-2-usama.arif@linux.dev> In-Reply-To: <20260310145406.3073394-1-usama.arif@linux.dev> References: <20260310145406.3073394-1-usama.arif@linux.dev> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: AA97E120005 X-Stat-Signature: smgin7eceny7htk1h46bxiozsrewnz4t X-Rspam-User: X-HE-Tag: 1773154481-642936 X-HE-Meta: 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 9qFlScM5 S/V5PNNz/Z9CkxR538s5QCGiDinStAzOl6fSthUZejOKxJS3YXt8BnFtCVirlN+gSg+NNo2ctEjSMCSw7d1D05vKUqZeCQ8LNt1zoXI/YYsKcgET/1/QkaV/hzTI7HT6ZZMvKQqzGhJBv22KhvX2nlEkJ0JbqWi8j0I6B8/Fy+mU59ZPJAVc1SY/fKzU2qcPZZSnEhtAntpn8kq2aw1NT7tJXu1x1uomuRd1rX60XaGPmnTGs8J+dZmhJos8E2cDka1vwiutHLd/AL5ky9ZCxcekkEL5wzYSjhY9L Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: exec_folio_order() was introduced [1] to request readahead of executable file-backed pages at an arch-preferred folio order, so that the hardware can coalesce contiguous PTEs into fewer iTLB entries (contpte). The current implementation uses ilog2(SZ_64K >> PAGE_SHIFT), which requests 64K folios. This is optimal for 4K base pages (where CONT_PTES = 16, contpte size = 64K), but suboptimal for 16K and 64K base pages: Page size | Before (order) | After (order) | contpte ----------|----------------|---------------|-------- 4K | 4 (64K) | 4 (64K) | Yes (unchanged) 16K | 2 (64K) | 7 (2M) | Yes (new) 64K | 0 (64K) | 5 (2M) | Yes (new) For 16K pages, CONT_PTES = 128 and the contpte size is 2M (order 7). For 64K pages, CONT_PTES = 32 and the contpte size is 2M (order 5). Use ilog2(CONT_PTES) instead, which directly evaluates to contpte-aligned order for all page sizes. The worst-case waste is bounded to one folio (up to 2MB - 64KB) at the end of the file, since page_cache_ra_order() reduces the folio order near EOF to avoid allocating past i_size. [1] https://lore.kernel.org/all/20250430145920.3748738-6-ryan.roberts@arm.com/ Signed-off-by: Usama Arif --- arch/arm64/include/asm/pgtable.h | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-) diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h index b3e58735c49bd..a1110a33acb35 100644 --- a/arch/arm64/include/asm/pgtable.h +++ b/arch/arm64/include/asm/pgtable.h @@ -1600,12 +1600,11 @@ static inline void update_mmu_cache_range(struct vm_fault *vmf, #define arch_wants_old_prefaulted_pte cpu_has_hw_af /* - * Request exec memory is read into pagecache in at least 64K folios. This size - * can be contpte-mapped when 4K base pages are in use (16 pages into 1 iTLB - * entry), and HPA can coalesce it (4 pages into 1 TLB entry) when 16K base - * pages are in use. + * Request exec memory is read into pagecache in contpte-sized folios. The + * contpte size is the number of contiguous PTEs that the hardware can coalesce + * into a single iTLB entry: 64K for 4K pages, 2M for 16K and 64K pages. */ -#define exec_folio_order() ilog2(SZ_64K >> PAGE_SHIFT) +#define exec_folio_order() ilog2(CONT_PTES) static inline bool pud_sect_supported(void) { -- 2.47.3