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 9B866C55182 for ; Wed, 5 Aug 2026 07:54:58 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id B9A946B00AC; Wed, 5 Aug 2026 03:54:57 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id B71176B00AD; Wed, 5 Aug 2026 03:54:57 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id AAE696B00AF; Wed, 5 Aug 2026 03:54:57 -0400 (EDT) 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 887C46B00AC for ; Wed, 5 Aug 2026 03:54:57 -0400 (EDT) Received: from smtpin18.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay10.hostedemail.com (Postfix) with ESMTP id 93563C03CC for ; Wed, 5 Aug 2026 07:54:56 +0000 (UTC) X-FDA: 85066454592.18.5C43A7C Received: from out-188.mta1.migadu.com (out-188.mta1.migadu.com [95.215.58.188]) by imf03.hostedemail.com (Postfix) with ESMTP id CB51A20007 for ; Wed, 5 Aug 2026 07:54:54 +0000 (UTC) Authentication-Results: imf03.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=WTf6PIsg; spf=pass (imf03.hostedemail.com: domain of baoquan.he@linux.dev designates 95.215.58.188 as permitted sender) smtp.mailfrom=baoquan.he@linux.dev; dmarc=pass (policy=none) header.from=linux.dev ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1785916494; 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-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=KQPF9NpoXms5JqUk+wWG0b5ssSUK6sTaQPnJLeO/Wgc=; b=6s782hxwWwTJRu88lwFs+uzxA/zXaeppbXZqZwpEiJ3Tfa5e9C273X1vvDnqRuyfQt3qWU y/yfkOCc37wxL87dmXwQwPRjWandNLij7d+Pw+l0MK5zRhPRNW+xo8Zgh7AWToRAjyuygT IRnetmuva1i9w7B5EG5zZihubGKETzY= ARC-Authentication-Results: i=1; imf03.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=WTf6PIsg; spf=pass (imf03.hostedemail.com: domain of baoquan.he@linux.dev designates 95.215.58.188 as permitted sender) smtp.mailfrom=baoquan.he@linux.dev; dmarc=pass (policy=none) header.from=linux.dev ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1785916494; b=3pBKp26sBTz6lJ/FSszd41aTUkrjdJ4hzSadpimcjI8wgGWb69amTW7rhCak+0zQvxJGFo J+HUPU0GFg+somqQGk5ybZSdXbpDyWzrzAOGHeePLRZ+QFKYBqcEIUG9kxsnAhdVJiCSxt MSSgCTvWObYjrYVc2Egaii7JWdXI0hw= X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1785916493; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=KQPF9NpoXms5JqUk+wWG0b5ssSUK6sTaQPnJLeO/Wgc=; b=WTf6PIsgJKrF3nj0UfO/kXgdoFHWcAZIMMiQtM5TabV1fluZmpgG0uKdbdZKRSg62tLfXT sFrrnvfe5jPh5tVLZVdGvzdHlRyVVhmPUwQeLsbGawGSKzWB+6MVaKMxIW99TXl3MxwIJM ZnAaw97ElGJcefECReEWYaPZmZChrqU= From: Baoquan He To: linux-mm@kvack.org Cc: chrisl@kernel.org, nphamcs@gmail.com, kasong@tencent.com, baohua@kernel.org, youngjun.park@lge.com, hannes@cmpxchg.org, yosry@kernel.org, david@kernel.org, shikemeng@huaweicloud.com, chengming.zhou@linux.dev, linux-kernel@vger.kernel.org, Baoquan He Subject: [RFC PATCH v2 06/10] mm, swap: free backing pages in xswap_unmap_clusters Date: Wed, 5 Aug 2026 15:53:29 +0800 Message-ID: <20260805075336.3579395-7-baoquan.he@linux.dev> In-Reply-To: <20260805075336.3579395-1-baoquan.he@linux.dev> References: <20260805075336.3579395-1-baoquan.he@linux.dev> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-type: text/plain Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT X-Stat-Signature: knosocqga4wdwdh58wi1wmr3bjjn4ub3 X-Rspamd-Queue-Id: CB51A20007 X-Rspam-User: X-Rspamd-Server: rspam06 X-HE-Tag: 1785916494-33393 X-HE-Meta: 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 m+71sFWE sOP8cAnJUfQjufuIcC6MUHm0F4hp1h1noRUHtLImEyVMISkat7hyj17dcE9BXy/FL+YjPPctksntkaxkDWM79vF8QBnVdFMcmVlgdEfLhoB2bwNV/9TlIq07wCKeKTSpEKWlYJcGL+jvVe98jcDiAcrwCuOjXY0IC27xy1lboELxf3Vd2L81KngArv2Xl2A090rZS9o1KDDq3dRkjU2iUuPAUZilMfuL8s+mw170bRaTiZURHW/gZCuV+GmsqBcQ97lUyw0W++Q45pR+gSfGVPcnvxqTJkrrczDpM9UZZAAvZVSn7MZyRfQBS/qFfL7DOG7xDwcIiKe4dpGG/WA/82C1GYw== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: vm_area_unmap_pages() only clears PTEs and frees intermediate page table pages — it does not free the backing physical pages allocated by xswap_map_clusters(). Fix this by walking the page table with apply_to_existing_page_range() before the unmap to collect all struct pages in the range. After vunmap_range() clears the PTEs, free the collected pages via __free_page(). Use a simple xswap_page_data collector callback: for each present PTE, collect pte_page() into a dynamically allocated array. The array is freed after the pages are released. Signed-off-by: Baoquan He --- mm/swapfile.c | 52 +++++++++++++++++++++++++++++++++++++++++++++------ 1 file changed, 46 insertions(+), 6 deletions(-) diff --git a/mm/swapfile.c b/mm/swapfile.c index 0d1d0c5e24c6..c43c8746378e 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -3796,6 +3796,23 @@ static int xswap_map_clusters(struct swap_info_struct *si, return -ENOMEM; } +struct xswap_page_data { + struct page **pages; + int nr; + int max; +}; + +static int xswap_collect_page(pte_t *pte, unsigned long addr, void *data) +{ + struct xswap_page_data *xpd = data; + + if (!pte_present(*pte)) + return 0; + if (xpd->nr < xpd->max) + xpd->pages[xpd->nr++] = pte_page(*pte); + return 0; +} + static void xswap_unmap_clusters(struct swap_info_struct *si, unsigned long start_idx, unsigned long nr) { @@ -3805,11 +3822,15 @@ static void xswap_unmap_clusters(struct swap_info_struct *si, /* * Round to page boundaries: start up (skip partial page that may * contain clusters still in use before start_idx), end up so the - * entire range is covered. vm_area_unmap_pages() operates on - * whole pages. + * entire range is covered. vm_area_unmap_pages() and + * apply_to_existing_page_range() operate on whole pages. */ unsigned long vm_start = PAGE_ALIGN(start_addr); unsigned long vm_end = PAGE_ALIGN(end_addr); + unsigned long size; + unsigned long npages; + struct xswap_page_data xpd; + int i; mutex_lock(&si->xswap_lock); @@ -3818,12 +3839,31 @@ static void xswap_unmap_clusters(struct swap_info_struct *si, goto out; } - vm_area_unmap_pages(si->cluster_vm, vm_start, vm_end); + size = vm_end - vm_start; + npages = size >> PAGE_SHIFT; + /* - * vm_area_unmap_pages() only clears PTEs; it does not free the - * physical pages. Walk the page table to find and free them. + * Walk the page table to collect physical pages before unmapping. + * vm_area_unmap_pages() only clears PTEs and frees intermediate + * page table pages — it does not free backing pages. */ - /* TODO: free backing pages via page table walk or tracking bitmap */ + xpd.pages = kmalloc_array(npages, sizeof(*xpd.pages), GFP_KERNEL); + if (xpd.pages) { + xpd.nr = 0; + xpd.max = npages; + apply_to_existing_page_range(&init_mm, vm_start, size, + xswap_collect_page, &xpd); + } + + vm_area_unmap_pages(si->cluster_vm, vm_start, vm_end); + + /* Free the collected backing pages */ + if (xpd.pages) { + for (i = 0; i < xpd.nr; i++) + __free_page(xpd.pages[i]); + kfree(xpd.pages); + } + mutex_unlock(&si->xswap_lock); out: -- 2.54.0