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 94623E63CB1 for ; Sun, 25 Jan 2026 17:58:09 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 0AF016B0088; Sun, 25 Jan 2026 12:58:09 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 02F2C6B0089; Sun, 25 Jan 2026 12:58:08 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id E8A646B008A; Sun, 25 Jan 2026 12:58:08 -0500 (EST) 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 CE5206B0088 for ; Sun, 25 Jan 2026 12:58:08 -0500 (EST) Received: from smtpin28.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay02.hostedemail.com (Postfix) with ESMTP id 5B8F513A1BA for ; Sun, 25 Jan 2026 17:58:08 +0000 (UTC) X-FDA: 84371245056.28.024C28A Received: from mail-pf1-f169.google.com (mail-pf1-f169.google.com [209.85.210.169]) by imf11.hostedemail.com (Postfix) with ESMTP id 660B44000A for ; Sun, 25 Jan 2026 17:58:06 +0000 (UTC) Authentication-Results: imf11.hostedemail.com; dkim=pass header.d=gmail.com header.s=20230601 header.b=nlSuNCRb; spf=pass (imf11.hostedemail.com: domain of ryncsn@gmail.com designates 209.85.210.169 as permitted sender) smtp.mailfrom=ryncsn@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=1769363886; 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-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=JXkKpfW2fKRP2DHBX2nOhkvpUQvYM7wlOqYMZBE7moY=; b=X4z9QJ+mXG4iy7aNJOmpMTs3e07FDja0svCLMWpBbqWq4KoretVOq9MYYhLnDrCJGqqf7i rRTgp76tJxh8y5GRtZqyK/2w6XUY3jT3RH1YAIMLwXFFefBIq5JxUrIAqHqsRp3PRy/IMH t24/GSJW/kErZbN0HSzmVfH97eZ1HBo= ARC-Authentication-Results: i=1; imf11.hostedemail.com; dkim=pass header.d=gmail.com header.s=20230601 header.b=nlSuNCRb; spf=pass (imf11.hostedemail.com: domain of ryncsn@gmail.com designates 209.85.210.169 as permitted sender) smtp.mailfrom=ryncsn@gmail.com; dmarc=pass (policy=none) header.from=gmail.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1769363886; a=rsa-sha256; cv=none; b=POOuWLeKF5XmHjrlWCi6cyYzboh47EL4HCR5cNWuPkQo+StDSnAi/CfZy0a16VrmnlrOiL /0sMroHEIxx9dnEIyF2BgPbxmBXlXN81mDNUoDdde+q3U1W3uvL1VwzyqlJWjcK4yS9X/z 1eYuvp0CN8aVhQcI6auCrwTu31oZnAE= Received: by mail-pf1-f169.google.com with SMTP id d2e1a72fcca58-81f4ba336b4so3828575b3a.1 for ; Sun, 25 Jan 2026 09:58:06 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1769363885; x=1769968685; darn=kvack.org; h=cc:to:in-reply-to:references:message-id:content-transfer-encoding :mime-version:subject:date:from:from:to:cc:subject:date:message-id :reply-to; bh=JXkKpfW2fKRP2DHBX2nOhkvpUQvYM7wlOqYMZBE7moY=; b=nlSuNCRbA8roFqNStUj33TG/PxQ462GC45UPHwT3MpBANg9C9CshgJmN985uNnT1D0 LpLXiBEEW48yDLJFt+8LYWdNWDYqkFw+rj3VYOfIZFS2DVs9/19EXVd4lhdJSNGInBAz CTI7gl53PPxfPgp2BQvjpDpSH49dRtbccPtycVNb6WjtfCSYpJ/wVjC9S+jzEDDQQB3H oRdVphVzpbrn9JbJdfU17jyNU6c0DHclzhKfpiN1ymECS39T7JS4vk/I1efkw/5lcmXC Hl10nSChN8PVE0yUzoKLh/l6hEvcSwRGhKC3B9zGE5zQ4rJ4fBhsIc8YJziZwZ98EtjY bYeg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1769363885; x=1769968685; h=cc:to:in-reply-to:references:message-id:content-transfer-encoding :mime-version:subject:date:from:x-gm-gg:x-gm-message-state:from:to :cc:subject:date:message-id:reply-to; bh=JXkKpfW2fKRP2DHBX2nOhkvpUQvYM7wlOqYMZBE7moY=; b=AnO9YJVpz59FShyjZ+f4U4nknhuredzFqfDjrxXG4gh530tHQatNL/Xs0pF/8iKQqF Rk3UHD5QavAj9GyvnfnokFG04RpH/eo3kKwZGigPQo2TCywXroUnKPNEP2elfewG1pdl MQ0W5pKWgsMwBHW0s4Tywg875MrPT9gGvHEUYvmatoX8hedLYPEPI2db87WRYeOVirsD NvIdR+njgujoygKP6hYdLJs3gIMAZgiazZjnRAk3ZkrbNPxwcS0/LiRo1CMqY6DyPmzP tjaFcTtxwWsBKd0/J1E+xoLJDC4ae3yKNlqLiPf7aU3A/bYcO+s0Bv9GaXJAMgGrp71Z yKsQ== X-Gm-Message-State: AOJu0Yz22uUHj/Ey6S5H34NciW5xcXPQHYk+lIz24Ow8/UtG1ELz61QJ fl2FVQgw8Z/MJj86OI1YG1RZ+hHHSzKtRD4RS6zUXN4sD8v4nHiKTJ/I X-Gm-Gg: AZuq6aJwyVYhIp5gwB+13M9AjxBnDF9FMczSx/HEpjptt4xBkQTf6KkN5bCw2pnI53Z 5XD/KgB0tJzuK70ER1CPMA9UCmw6oQ8TplBzCRhmJKCrctLurAh7gYOgdam97GF+Ut//3yzjcau 0x1IcxtxiaVcJTWhXjiBDWHBWh/4QbBRnheAvGQFoa+ZO4X3BqUlNMlx3yK434SK/yGTVeyeHXH TI5D9OgthyzNJHvnyJi9bLHXANqF7eT31d3WfoIYaPFf3vcZFupCX8FijjnLSddcXj57RKGgUEk asjDXmMH9AHeeDODe77MDXk3v6feA7WK1F7KHnYwUIE1o9LyiUWa1ndoaj7Z4vCCu8vVNq/CJDV +jhZKJTlnKzZcduOegXK/bNKDPydHxrpHlLGn0IkyOStfs09V2FbhVt2XVNrQdwKTd0U5idDzb7 4SQlxiKSM0cXvfTuoOQ4QPUEDQXqpINcxC9Uuzsy44S0HK2aEg X-Received: by 2002:a05:6a00:761b:b0:81f:4f74:2246 with SMTP id d2e1a72fcca58-823411fa543mr1939435b3a.16.1769363885303; Sun, 25 Jan 2026 09:58:05 -0800 (PST) Received: from [127.0.0.1] ([101.32.222.185]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-8231876e718sm7405963b3a.62.2026.01.25.09.58.02 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 25 Jan 2026 09:58:04 -0800 (PST) From: Kairui Song Date: Mon, 26 Jan 2026 01:57:24 +0800 Subject: [PATCH 01/12] mm, swap: protect si->swap_file properly and use as a mount indicator MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20260126-swap-table-p3-v1-1-a74155fab9b0@tencent.com> References: <20260126-swap-table-p3-v1-0-a74155fab9b0@tencent.com> In-Reply-To: <20260126-swap-table-p3-v1-0-a74155fab9b0@tencent.com> To: linux-mm@kvack.org Cc: Andrew Morton , Kemeng Shi , Nhat Pham , Baoquan He , Barry Song , Johannes Weiner , David Hildenbrand , Lorenzo Stoakes , linux-kernel@vger.kernel.org, Chris Li , Kairui Song X-Mailer: b4 0.14.3 X-Developer-Signature: v=1; a=ed25519-sha256; t=1769363877; l=5423; i=kasong@tencent.com; s=kasong-sign-tencent; h=from:subject:message-id; bh=KCJ3euqA2qAaRKKZ+5BOjIB6OnqWy66OxHgNUHCngaI=; b=+gz5DUR9sRm7/DlBjNBzpGMqXfRha1zGai1p/b3tbjYg8aHCenc1uarNGtadbcM3aoVmafff+ 2wiceVFdUL4Dxgv2A1SJdkzRw26+MZR2C8HV9/QumIzrQcZay8aRMDm X-Developer-Key: i=kasong@tencent.com; a=ed25519; pk=kCdoBuwrYph+KrkJnrr7Sm1pwwhGDdZKcKrqiK8Y1mI= X-Rspamd-Server: rspam12 X-Stat-Signature: erm7iateha8eqbor7ak61n9odn97sse7 X-Rspamd-Queue-Id: 660B44000A X-Rspam-User: X-HE-Tag: 1769363886-30110 X-HE-Meta: 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 hGufgTsL HK3MIMh8eeomXSgpr3GjAZuCQO4o4A+0yPYU41v433Z4hyQLrFQYGdpLVBmu59HE549VOluHo3nEFVI8s6cdcm0Yrr1KRJ1bdlMs6u9PHy4OAEOupMiXG3lIp64hllO8k4rvnH1v+BIkhIKCAiT7jJZY4lu25ske0XUCjad4XAso0PjScL8U7IYlulGLUAmTEHxgJA+BFlS8beCeWZiJPN857NFkzFUoPPEK4GDYIHfi2CHcOGPth0KN/Wf7/NjUv1AjcNYVodeGmpCFojjUhhG8W23mFm8Ox+hQqMp0tqvB/P5qtA+09kHKvVonhkqfqHzdMubLDUq375OXlI+hC2lIIrxsLmxLPWxWiQKyexde8OF8NiHHE2Oj9tP1bntpGlJDXXJrY8I0ehJSLw8odwwKPvCsghb3akPTILyKy0gwPnhgecLa3nCSHE3cSNqzdan/o5Vgro+sXZediq0PXj2DbF6coCM316F4i1G5DmALAt0b9Rcgb1bqTzRxM6NjTf6jDzc63Ht6jWwcPJ7VXD8+MdkCQSTxeqA4CpaK7osUWf2FJqD+nE5muhJE7fgrdIOMo 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: From: Kairui Song /proc/swaps uses si->swap_map as the indicator to check if the swap device is mounted. swap_map will be removed soon, so change it to use si->swap_file instead because: - si->swap_file is exactly the only dynamic content that /proc/swaps is interested in. Previously, it was checking si->swap_map just to ensure si->swap_file is available. si->swap_map is set under mutex protection, and after si->swap_file is set, so having si->swap_map set guarantees si->swap_file is set. - Checking si->flags doesn't work here. SWP_WRITEOK is cleared during swapoff, but /proc/swaps is supposed to show the device under swapoff too to report the swapoff progress. And SWP_USED is set even if the device hasn't been properly set up. We can have another flag, but the easier way is to just check si->swap_file directly. So protect si->swap_file setting with mutext, and set si->swap_file only when the swap device is truly enabled. /proc/swaps only interested in si->swap_file and a few static data reading. Only si->swap_file needs protection. Reading other static fields is always fine. Signed-off-by: Kairui Song --- mm/swapfile.c | 25 +++++++++++++------------ 1 file changed, 13 insertions(+), 12 deletions(-) diff --git a/mm/swapfile.c b/mm/swapfile.c index 7b055f15d705..521f7713a7c3 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -110,6 +110,7 @@ struct swap_info_struct *swap_info[MAX_SWAPFILES]; static struct kmem_cache *swap_table_cachep; +/* Protects si->swap_file for /proc/swaps usage */ static DEFINE_MUTEX(swapon_mutex); static DECLARE_WAIT_QUEUE_HEAD(proc_poll_wait); @@ -2521,7 +2522,8 @@ static void drain_mmlist(void) /* * Free all of a swapdev's extent information */ -static void destroy_swap_extents(struct swap_info_struct *sis) +static void destroy_swap_extents(struct swap_info_struct *sis, + struct file *swap_file) { while (!RB_EMPTY_ROOT(&sis->swap_extent_root)) { struct rb_node *rb = sis->swap_extent_root.rb_node; @@ -2532,7 +2534,6 @@ static void destroy_swap_extents(struct swap_info_struct *sis) } if (sis->flags & SWP_ACTIVATED) { - struct file *swap_file = sis->swap_file; struct address_space *mapping = swap_file->f_mapping; sis->flags &= ~SWP_ACTIVATED; @@ -2615,9 +2616,9 @@ EXPORT_SYMBOL_GPL(add_swap_extent); * Typically it is in the 1-4 megabyte range. So we can have hundreds of * extents in the rbtree. - akpm. */ -static int setup_swap_extents(struct swap_info_struct *sis, sector_t *span) +static int setup_swap_extents(struct swap_info_struct *sis, + struct file *swap_file, sector_t *span) { - struct file *swap_file = sis->swap_file; struct address_space *mapping = swap_file->f_mapping; struct inode *inode = mapping->host; int ret; @@ -2635,7 +2636,7 @@ static int setup_swap_extents(struct swap_info_struct *sis, sector_t *span) sis->flags |= SWP_ACTIVATED; if ((sis->flags & SWP_FS_OPS) && sio_pool_init() != 0) { - destroy_swap_extents(sis); + destroy_swap_extents(sis, swap_file); return -ENOMEM; } return ret; @@ -2851,7 +2852,7 @@ SYSCALL_DEFINE1(swapoff, const char __user *, specialfile) flush_work(&p->reclaim_work); flush_percpu_swap_cluster(p); - destroy_swap_extents(p); + destroy_swap_extents(p, p->swap_file); if (p->flags & SWP_CONTINUED) free_swap_count_continuations(p); @@ -2941,7 +2942,7 @@ static void *swap_start(struct seq_file *swap, loff_t *pos) return SEQ_START_TOKEN; for (type = 0; (si = swap_type_to_info(type)); type++) { - if (!(si->flags & SWP_USED) || !si->swap_map) + if (!(si->swap_file)) continue; if (!--l) return si; @@ -2962,7 +2963,7 @@ static void *swap_next(struct seq_file *swap, void *v, loff_t *pos) ++(*pos); for (; (si = swap_type_to_info(type)); type++) { - if (!(si->flags & SWP_USED) || !si->swap_map) + if (!(si->swap_file)) continue; return si; } @@ -3379,7 +3380,6 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags) goto bad_swap; } - si->swap_file = swap_file; mapping = swap_file->f_mapping; dentry = swap_file->f_path.dentry; inode = mapping->host; @@ -3429,7 +3429,7 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags) si->max = maxpages; si->pages = maxpages - 1; - nr_extents = setup_swap_extents(si, &span); + nr_extents = setup_swap_extents(si, swap_file, &span); if (nr_extents < 0) { error = nr_extents; goto bad_swap_unlock_inode; @@ -3538,6 +3538,8 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags) prio = DEF_SWAP_PRIO; if (swap_flags & SWAP_FLAG_PREFER) prio = swap_flags & SWAP_FLAG_PRIO_MASK; + + si->swap_file = swap_file; enable_swap_info(si, prio, swap_map, cluster_info, zeromap); pr_info("Adding %uk swap on %s. Priority:%d extents:%d across:%lluk %s%s%s%s\n", @@ -3562,10 +3564,9 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags) kfree(si->global_cluster); si->global_cluster = NULL; inode = NULL; - destroy_swap_extents(si); + destroy_swap_extents(si, swap_file); swap_cgroup_swapoff(si->type); spin_lock(&swap_lock); - si->swap_file = NULL; si->flags = 0; spin_unlock(&swap_lock); vfree(swap_map); -- 2.52.0