From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id A2E9D1094478 for ; Sat, 21 Mar 2026 14:21:36 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id E32146B00BA; Sat, 21 Mar 2026 10:21:35 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id DE2746B00BB; Sat, 21 Mar 2026 10:21:35 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id CD0CE6B00BC; Sat, 21 Mar 2026 10:21:35 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0013.hostedemail.com [216.40.44.13]) by kanga.kvack.org (Postfix) with ESMTP id BBD796B00BA for ; Sat, 21 Mar 2026 10:21:35 -0400 (EDT) Received: from smtpin14.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay06.hostedemail.com (Postfix) with ESMTP id 7A36F1B8219 for ; Sat, 21 Mar 2026 14:21:35 +0000 (UTC) X-FDA: 84570283350.14.ABE70E3 Received: from mail-pl1-f174.google.com (mail-pl1-f174.google.com [209.85.214.174]) by imf24.hostedemail.com (Postfix) with ESMTP id 9518C180006 for ; Sat, 21 Mar 2026 14:21:33 +0000 (UTC) Authentication-Results: imf24.hostedemail.com; dkim=pass header.d=hev-cc.20230601.gappssmtp.com header.s=20230601 header.b=IYXk0gNB; spf=pass (imf24.hostedemail.com: domain of r@hev.cc designates 209.85.214.174 as permitted sender) smtp.mailfrom=r@hev.cc; dmarc=none ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1774102893; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=FFdEgLKBQwl/qBMdiHVw8eCe65OPPezRSACDbsiut88=; b=vqMHQSwHsitl0wrF3WY2zMjCdkX7n13eya6k4OAXaNJ/1cplER2460E0eL6ue93bGKa79c TDb7/YgNb2k8vr0tnWeNEDIZyRJpH5TYjmY4sCZbxy5v4zAnt6PxIHOB5EgDHwjIvaGa+d r9+AtCaM1SAxCUTg/Bc+TCsuGlLC1UY= ARC-Authentication-Results: i=1; imf24.hostedemail.com; dkim=pass header.d=hev-cc.20230601.gappssmtp.com header.s=20230601 header.b=IYXk0gNB; spf=pass (imf24.hostedemail.com: domain of r@hev.cc designates 209.85.214.174 as permitted sender) smtp.mailfrom=r@hev.cc; dmarc=none ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1774102893; a=rsa-sha256; cv=none; b=5Ap1SFVHBAW0M27qUQPPxmLhvx3pOtSbeKGaMhZgr99+4cIBXI8iyE9zL9tDfbQSKEzRN9 SVIszUREYbO8WXl09Lw5oqYJShUnolD4gVkCIOgLAeMolRJfR9Rl9IXmJDcnbNiYQpNZlU nExn4xXLA9VF2+rmjIVOj8NTsfxPYy8= Received: by mail-pl1-f174.google.com with SMTP id d9443c01a7336-2b0484a6de4so12181905ad.3 for ; Sat, 21 Mar 2026 07:21:33 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=hev-cc.20230601.gappssmtp.com; s=20230601; t=1774102892; x=1774707692; darn=kvack.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=FFdEgLKBQwl/qBMdiHVw8eCe65OPPezRSACDbsiut88=; b=IYXk0gNB99bSadophVm+Q3BrCUyzJYC/enCR1CnTDXIlXXyGBV4IADcb7/yb5VhVdi Kr/uNLxoZf2nuFLMny33a2lHBhm3qQ9S044urGCiMdnGwRJXiCrS/83E5721iRR/0Tra Zy7WMZ3nFEUi10MEeWIOBvQz2g/Xw9pSc7H9xMjtpWXklvDuDchPvPLxaokM+YKTQV/7 sCavxjuVzX5CH3IkbSlGPf7QiMIQk0l7S6oZ9t1IXmNRlOuirgGyE4bOiXNnRej8/D+U TaR6s9x0zWPOPHzfmK8A2nI4VcY5eCTamO1jIwdE6FCDgUj6aPwYxrHd+d4Vz7ZjdGlM 8CqQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1774102892; x=1774707692; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-gg:x-gm-message-state:from :to:cc:subject:date:message-id:reply-to; bh=FFdEgLKBQwl/qBMdiHVw8eCe65OPPezRSACDbsiut88=; b=meiLSKiu4duEGdYtpgahtdp/b1f6ps88fDsPF2hViAN1oHBfjgEQSPZkcXkap5Cbb2 ccJDy8/DyCZaZNzvkKSxq7Xv1dEhYyeKYkYlHAh5+N6se3Am9H8ZJ4svFcagP53M+xEA WqIaLlPBC1+WQAfluq3WIPmZYJb3zNgEZfiGgI10xhcyI9ONpNBVpsUxoU5GpymwHpnd lcadlQz4PuyY4CC+dNzEk9aEfpOvy+M0yaBCoGRDUhN2mDdm41Q532Mk44P2RHwQZncK sIm9pYE/PQobRgg3g1NEEQnF5SeYbAuahj7wXCJmCFBwTBvq+tJEMq+4bFkerucOvTrR glcQ== X-Forwarded-Encrypted: i=1; AJvYcCUO7lA6S4lZAmoSV9jKNTVPf44qppoH/xCWdG1nJNJqZw+d904d3cyQeb+TicV77w1Lrva27DiLbA==@kvack.org X-Gm-Message-State: AOJu0YyWhKLAKUjk2icQ2ugVtxHP4x3+CnsxK+ZrDV7Vtws9sHYyh9Kq 32XcyV2tniW89yfM/gFeu4qQNc3OJiomW09hVaNii58atgDbSMA32/cp2ZQ+lFBABVI= X-Gm-Gg: ATEYQzw14Wn14nseieDLH2wgv6ubA5pgvMQVp/EzIaBb4NHQ3dqHtuIltdotbpLrElV /8cOGVNEkFJ6epvFmWpOh1mTpf6BU+Ql/LyxuB++R/oEUljLce3dq8xPJjVLvnpx6cqFolS1Vd3 tljZq8JHhGj8Tmbyk28U7qU22rkmhk2r3aCDI/dVYLM+gWpv5s+uF+/NlFefIYBxSkQeYlMDZ6V ofN39sAibmDqGy5fim8+khDjSSjIg0DbvDO34MM2/g8a04uKDwym/6t6dJ4LQpTFTRVJNKP65l6 spelVVqFymHEtt+s59cNSXWwJGVXMke2k8xKWfQwwDfG8FJHJFPtEbUggYtFpLeXJ38JGy6nTl0 QctjV3b6n+aDeUFCyW3kqByHB1cgvjUYj5bnoKqSeiHU/Fp6iuL1bUUxCn27TmzyOEb8iMqTTig iY X-Received: by 2002:a17:902:eccb:b0:2b0:8106:f3ad with SMTP id d9443c01a7336-2b0827c7f52mr60674775ad.29.1774102892319; Sat, 21 Mar 2026 07:21:32 -0700 (PDT) Received: from gpc ([2400:8902:e002:ded5:78c1:8178:95c1:6ca3]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2b083656df5sm70621765ad.44.2026.03.21.07.21.25 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 21 Mar 2026 07:21:31 -0700 (PDT) From: WANG Rui To: david@kernel.org, usama.arif@linux.dev, willy@infradead.org, baolin.wang@linux.alibaba.com Cc: r@hev.cc, Liam.Howlett@oracle.com, ajd@linux.ibm.com, akpm@linux-foundation.org, apopple@nvidia.com, baohua@kernel.org, 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, linux-arm-kernel@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, lorenzo.stoakes@oracle.com, mhocko@suse.com, npache@redhat.com, pasha.tatashin@soleen.com, rmclure@linux.ibm.com, rppt@kernel.org, ryan.roberts@arm.com, surenb@google.com, vbabka@kernel.org, viro@zeniv.linux.org.uk Subject: Re: [PATCH v5] binfmt_elf: Align eligible read-only PT_LOAD segments to PMD_SIZE for THP Date: Sat, 21 Mar 2026 22:21:19 +0800 Message-ID: <20260321142119.102525-1-r@hev.cc> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260320171115.93235-1-r@hev.cc> References: <20260320171115.93235-1-r@hev.cc> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 9518C180006 X-Stat-Signature: sr89mm7hoygg99w9u56qtd4xocu9rgus X-Rspam-User: X-HE-Tag: 1774102893-298221 X-HE-Meta: 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 Vuc5IqFn 5d9eXMePSoMEWoOMfVuEtuxjjcdruMRARL8g9FEiHJr8Y5bNLAIBlk7tA6Ac1fEJ9dvqeiO4kfAw0XYztyDdBRY2gAw== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: One clarification regarding my earlier comment about compatibility with cont-pte. What I meant there is that the alignment logic in my patch does work for systems with 4K and 16K base pages, where the PMD size remains within a practical range. In those configurations, providing PMD-level alignment already creates the conditions needed for both THP collapse and cont-pte coalescing. This does not fully extend to 64K base page systems. There the PMD size can be quite large (e.g. 512M), which exceeds the 32M cap used in my patch, so PMD-sized alignment may not be achievable in practice. One way to structure this could be to treat alignment in a layered manner. My patch focuses on establishing a reliable PMD-level alignment baseline so that THP has the opportunity to form large mappings where it is practical. On top of that, Usama's work can further improve behavior at smaller granularities, for example by enabling cont-pte mappings when PMD alignment is not feasible. /* skip non-power of two alignments as invalid */ if (!is_power_of_2(p_align)) continue; if (p_align < PMD_SIZE && should_align_to_pmd(&cmds[i])) p_align = PMD_SIZE; + else if (p_align < CONT_PTE_SIZE && should_align_to_cont_pte(&cmds[i])) + p_align = CONT_PTE_SIZE; alignment = max(alignment, p_align); } } With that separation of roles, the two approaches complement each other, and we can get the benefit of both without changing the core alignment policy in binfmt_elf. Thanks, Rui