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 E34BBEF06F7 for ; Sun, 8 Feb 2026 21:59:03 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 77BF46B009B; Sun, 8 Feb 2026 16:59:00 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 6B4256B009D; Sun, 8 Feb 2026 16:59:00 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 4D7256B009E; Sun, 8 Feb 2026 16:59:00 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0010.hostedemail.com [216.40.44.10]) by kanga.kvack.org (Postfix) with ESMTP id 33A486B009B for ; Sun, 8 Feb 2026 16:59:00 -0500 (EST) Received: from smtpin06.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay06.hostedemail.com (Postfix) with ESMTP id 00D0C1B316E for ; Sun, 8 Feb 2026 21:59:00 +0000 (UTC) X-FDA: 84422655198.06.84A7946 Received: from mail-oi1-f182.google.com (mail-oi1-f182.google.com [209.85.167.182]) by imf30.hostedemail.com (Postfix) with ESMTP id 44B4280005 for ; Sun, 8 Feb 2026 21:58:58 +0000 (UTC) Authentication-Results: imf30.hostedemail.com; dkim=pass header.d=gmail.com header.s=20230601 header.b=R0nDCRXC; spf=pass (imf30.hostedemail.com: domain of nphamcs@gmail.com designates 209.85.167.182 as permitted sender) smtp.mailfrom=nphamcs@gmail.com; dmarc=pass (policy=none) header.from=gmail.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1770587938; 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=AAYGpIpTp87S2/ee6Fydv9Vv1Hcay3Vy8wBGMvAXEzA=; b=WEvISKebaIpmLptzna5R/Mc+f0UlbC6nhB7UaMg22LWXn4YDOeeL/bjrsOPp6G8qYTBWnK gIPiKfeHdutV3JhuIFqCJjL6Cn7Vi7qHtxn05HuZ2Qt/JABbLX2eR5iuQl4BEptVcgQ0KQ X1MswDbRkhGwnTcZUff3DohbWZDiqds= ARC-Authentication-Results: i=1; imf30.hostedemail.com; dkim=pass header.d=gmail.com header.s=20230601 header.b=R0nDCRXC; spf=pass (imf30.hostedemail.com: domain of nphamcs@gmail.com designates 209.85.167.182 as permitted sender) smtp.mailfrom=nphamcs@gmail.com; dmarc=pass (policy=none) header.from=gmail.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1770587938; a=rsa-sha256; cv=none; b=n6IOi924H1fN6KycjkHhIfuk+5PRe/Spr3JuVo3iJp4LOXxWwKhZ04y/yGoPZouqkjwaNe NYkqhiUQAT/kb6ohKmYMR2yOjNjNP4PM/Xo1wZy2P+TWKJH/bvtqfqK4SxDrivIymQG2WT g1Mom/1V6GwLJ0Fj/t5Nta4GtWDUB9w= Received: by mail-oi1-f182.google.com with SMTP id 5614622812f47-45c8b850f96so1670405b6e.0 for ; Sun, 08 Feb 2026 13:58:58 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1770587937; x=1771192737; 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=AAYGpIpTp87S2/ee6Fydv9Vv1Hcay3Vy8wBGMvAXEzA=; b=R0nDCRXCZK+PweHgA3aO3L0qVGW9gB2vOCg7GiLxHCO17PSMUp1GedavFfuF388GrW O7lJfFOOmf9TFFJo+vWLG6deWJG7c0SVSIGLRTm3hBAxuSOGy6YioJxIcriomuBLSjA9 2Csqq5Xn5PwmeaBPiT/E/d2+c286IZ2chgWt2aguxihqQm9J5qGBS3kd53NfIbNlw8T/ 5EDnyJyNdcKzFMe+Qf7IIhysdSNlIFd+eMtz8jyyJqJnjfHa6oA1kaNInvJLIOi5SsCA WF5eZUXu32Cpqke+NTMQVKSftq5yASRap5wAMj2YxGFv9jRPGXXpba8H3GZsIGaqZwz/ UsCQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1770587937; x=1771192737; 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=AAYGpIpTp87S2/ee6Fydv9Vv1Hcay3Vy8wBGMvAXEzA=; b=Vr6XEQUpqFblM4oPPTfhFAOWUCI/qpQetUxkLBqd28dLV7HvLtfqHp0jLO89a0kqny KLuZypjoC3/XjxdRU2rRFhnG0qU69mSh9d+w3iQbFJwlcf1Lhy1foh8EcMS8NHhmdvOD 0oPFJuf1uUVmkAGyeLHNO1hm18HfF4gjNyPrA+oYIq3Y+2/366sAjBhpqbo4A7tHAvI1 p/uHO7XBUwCOqP06cHWpE/yxZjn5Y2mpdWVGN/w129zft56/fosrZn6QyX8ZrTsBzoby tslLS1ofHpUuhrlyrrxjsN4fDkOXJxr9tjuR416RjC4OQ2P+D/SMIJcpD2yQ9Z626bX5 1ncg== X-Gm-Message-State: AOJu0YycScbYXPBk/scX9ppoIo6QAnvkMgdHw5hLxq1b7N+HFFNwj7F1 Qug0LB5WIeb5eA2Y/uE4wjLhHWsduF5ex/mqnK7EJ1bhKsYYF2Mwv1t5Uy8DGBcOYXXwyA== X-Gm-Gg: AZuq6aKJ876SHT4UWX0fuAxExk9qy0fqkj1At8WJ3OwOOAqUjvPFStPgjcZY/07mdr5 GglorSeacxyB6/9WjgQf6lSHC34yeKRhWudjK4Y2u8nBhXPh3/oKpj7oHo9pCFeaIIfN6U8X1Zw /vLMsyGDpSrBKQhokJm6eKeuG0wpwHE+P9lXuOT3Kvbi0JqcoRzAzO3mpqqvtyNql5Ff7UvwOUV 3NKZnp/jtN99dsq7K4eB6IQ/scbNDH9lQ0rrfUBdJCruYNCVBpd+o2OJBouDrwrTo70jxys2m2i HfJ5dyleIiINnKKhAdhK3RteAwrTYb7dB0cH24/0ilTv2ZjKhF7mDrhVAF4/0lGhTAvIj5c4Hn8 e76/mX/8XI0BHLvUcKf//paZTU21Cs5+NtUnHMlQewADI89bRjAYUFcbBb+a/oURG3GNDNe88m+ Cjemqy0hgCnQR5Zbke6Oe+FVpfM365jTQF X-Received: by 2002:a05:6808:6a83:b0:45e:84ec:f163 with SMTP id 5614622812f47-462fcbf61f5mr5120530b6e.64.1770587937297; Sun, 08 Feb 2026 13:58:57 -0800 (PST) Received: from localhost ([2a03:2880:10ff:1::]) by smtp.gmail.com with ESMTPSA id 46e09a7af769-7d464785674sm6238015a34.19.2026.02.08.13.58.56 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 08 Feb 2026 13:58:56 -0800 (PST) From: Nhat Pham To: linux-mm@kvack.org Cc: akpm@linux-foundation.org, hannes@cmpxchg.org, hughd@google.com, yosry.ahmed@linux.dev, mhocko@kernel.org, roman.gushchin@linux.dev, shakeel.butt@linux.dev, muchun.song@linux.dev, len.brown@intel.com, chengming.zhou@linux.dev, kasong@tencent.com, chrisl@kernel.org, huang.ying.caritas@gmail.com, ryan.roberts@arm.com, shikemeng@huaweicloud.com, viro@zeniv.linux.org.uk, baohua@kernel.org, bhe@redhat.com, osalvador@suse.de, lorenzo.stoakes@oracle.com, christophe.leroy@csgroup.eu, pavel@kernel.org, kernel-team@meta.com, linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, linux-pm@vger.kernel.org, peterx@redhat.com, riel@surriel.com, joshua.hahnjy@gmail.com, npache@redhat.com, gourry@gourry.net, axelrasmussen@google.com, yuanchu@google.com, weixugc@google.com, rafael@kernel.org, jannh@google.com, pfalcato@suse.de, zhengqi.arch@bytedance.com Subject: [PATCH v3 07/20] mm: create scaffolds for the new virtual swap implementation Date: Sun, 8 Feb 2026 13:58:20 -0800 Message-ID: <20260208215839.87595-8-nphamcs@gmail.com> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260208215839.87595-1-nphamcs@gmail.com> References: <20260208215839.87595-1-nphamcs@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam12 X-Stat-Signature: 89i38w8emur1bw9kkysoj66bu1m1dcgw X-Rspamd-Queue-Id: 44B4280005 X-Rspam-User: X-HE-Tag: 1770587938-48540 X-HE-Meta: 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 cKenKrdH 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: In prepration for the implementation of swap virtualization, add new scaffolds for the new code: a new mm/vswap.c source file, which currently only holds the logic to set up the (for now, empty) vswap debugfs directory. Hook this up in the swap setup step in mm/swap_state.c, and set up vswap compilation in the Makefile. Other than the debugfs directory, no behavioral change intended. Finally, make Johannes a swap reviewer, given that he has contributed majorly to the developments of virtual swap. Signed-off-by: Nhat Pham --- MAINTAINERS | 2 ++ include/linux/swap.h | 2 ++ mm/Makefile | 2 +- mm/swap_state.c | 6 ++++++ mm/vswap.c | 35 +++++++++++++++++++++++++++++++++++ 5 files changed, 46 insertions(+), 1 deletion(-) create mode 100644 mm/vswap.c diff --git a/MAINTAINERS b/MAINTAINERS index e087673237636..b21038b160a07 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -16728,6 +16728,7 @@ R: Kemeng Shi R: Nhat Pham R: Baoquan He R: Barry Song +R: Johannes Weiner L: linux-mm@kvack.org S: Maintained F: Documentation/mm/swap-table.rst @@ -16740,6 +16741,7 @@ F: mm/swap.h F: mm/swap_table.h F: mm/swap_state.c F: mm/swapfile.c +F: mm/vswap.c MEMORY MANAGEMENT - THP (TRANSPARENT HUGE PAGE) M: Andrew Morton diff --git a/include/linux/swap.h b/include/linux/swap.h index 918b47da55f44..1ff463fb3a966 100644 --- a/include/linux/swap.h +++ b/include/linux/swap.h @@ -669,6 +669,8 @@ static inline bool mem_cgroup_swap_full(struct folio *folio) } #endif +int vswap_init(void); + /** * swp_entry_to_swp_slot - look up the physical swap slot corresponding to a * virtual swap slot. diff --git a/mm/Makefile b/mm/Makefile index 2d0570a16e5be..67fa4586e7e18 100644 --- a/mm/Makefile +++ b/mm/Makefile @@ -75,7 +75,7 @@ ifdef CONFIG_MMU obj-$(CONFIG_ADVISE_SYSCALLS) += madvise.o endif -obj-$(CONFIG_SWAP) += page_io.o swap_state.o swapfile.o +obj-$(CONFIG_SWAP) += page_io.o swap_state.o swapfile.o vswap.o obj-$(CONFIG_ZSWAP) += zswap.o obj-$(CONFIG_HAS_DMA) += dmapool.o obj-$(CONFIG_HUGETLBFS) += hugetlb.o hugetlb_sysfs.o hugetlb_sysctl.o diff --git a/mm/swap_state.c b/mm/swap_state.c index e2e9f55bea3bb..29ec666be4204 100644 --- a/mm/swap_state.c +++ b/mm/swap_state.c @@ -882,6 +882,12 @@ static int __init swap_init(void) int err; struct kobject *swap_kobj; + err = vswap_init(); + if (err) { + pr_err("failed to initialize virtual swap space\n"); + return err; + } + swap_kobj = kobject_create_and_add("swap", mm_kobj); if (!swap_kobj) { pr_err("failed to create swap kobject\n"); diff --git a/mm/vswap.c b/mm/vswap.c new file mode 100644 index 0000000000000..e68234f053fc9 --- /dev/null +++ b/mm/vswap.c @@ -0,0 +1,35 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Virtual swap space + * + * Copyright (C) 2024 Meta Platforms, Inc., Nhat Pham + */ +#include + +#ifdef CONFIG_DEBUG_FS +#include + +static struct dentry *vswap_debugfs_root; + +static int vswap_debug_fs_init(void) +{ + if (!debugfs_initialized()) + return -ENODEV; + + vswap_debugfs_root = debugfs_create_dir("vswap", NULL); + return 0; +} +#else +static int vswap_debug_fs_init(void) +{ + return 0; +} +#endif + +int vswap_init(void) +{ + if (vswap_debug_fs_init()) + pr_warn("Failed to initialize vswap debugfs\n"); + + return 0; +} -- 2.47.3