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 25FCBC531FC for ; Mon, 27 Jul 2026 14:06:01 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 171A46B00A0; Mon, 27 Jul 2026 10:06:00 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 1486B6B00A1; Mon, 27 Jul 2026 10:06:00 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 086426B00A2; Mon, 27 Jul 2026 10:06:00 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0015.hostedemail.com [216.40.44.15]) by kanga.kvack.org (Postfix) with ESMTP id D5A1D6B00A0 for ; Mon, 27 Jul 2026 10:05:59 -0400 (EDT) Received: from smtpin03.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay02.hostedemail.com (Postfix) with ESMTP id 4F6DE120736 for ; Mon, 27 Jul 2026 14:05:59 +0000 (UTC) X-FDA: 85034730438.03.9DD48F1 Received: from out-173.mta1.migadu.com (out-173.mta1.migadu.com [95.215.58.173]) by imf07.hostedemail.com (Postfix) with ESMTP id 913A040012 for ; Mon, 27 Jul 2026 14:05:57 +0000 (UTC) Authentication-Results: imf07.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=gzl4GgGR; spf=pass (imf07.hostedemail.com: domain of baoquan.he@linux.dev designates 95.215.58.173 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=1785161157; 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=YIy7Qx8bWx3spNRm9c+a9lBeger9sWyHhg8HX/HO6dc=; b=zhnkPqVwvmLhiB0c4FMkwCeRsmDqriRz/FrRTn1DFj6kGjZ8RGSa7ZEKNt0UeqK3DcPfMo ypu3NOb+arWwrPcImcaUt54WY6qpT7jgobY+PL2a+OZ3X+I9G/6Y8t1CC9pF1bQIm0z4Zw 9gisLallaiRaUW0tGCcpIkmV5U6h2Cg= ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1785161157; b=dNjtLDv1A81GYLsDnS6KBDkMPDp8asMbUFwaT0Gy6d21UtEgJ0FUwS9y7Ul2Z9edtC6daW iGAxCdXFMNDEnDrLvSqwLMB+6uqAGvio7KUFbk3JqjUbOntjgoOX34YtqJwS1ElmrqBaSV Zu6cQhWLuSOvSP10LsW/3dIogi/U028= ARC-Authentication-Results: i=1; imf07.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=gzl4GgGR; spf=pass (imf07.hostedemail.com: domain of baoquan.he@linux.dev designates 95.215.58.173 as permitted sender) smtp.mailfrom=baoquan.he@linux.dev; dmarc=pass (policy=none) header.from=linux.dev 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=1785161156; 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=YIy7Qx8bWx3spNRm9c+a9lBeger9sWyHhg8HX/HO6dc=; b=gzl4GgGR4lMlT4GFvFX0H4fZvvSa2NxagVAz1kmeIT9am0LuT7+OuZjYu3dudnRZvFhOky AAXBCpsw1zqmvShsQCx76V1b5GncmImu0UdfcGWXCAA9GT6PdytI6yEHWCYGVore2Fxhf4 heog055s99I5etWPF+qIlajFLDAtnPM= From: Baoquan He To: linux-mm@kvack.org Cc: akpm@linux-foundation.org, 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 06/11] mm, swap: free backing pages in xswap_unmap_clusters Date: Mon, 27 Jul 2026 22:04:57 +0800 Message-ID: <20260727140503.1060918-5-baoquan.he@linux.dev> In-Reply-To: <20260727140503.1060918-1-baoquan.he@linux.dev> References: <20260727135029.1059441-1-baoquan.he@linux.dev> <20260727140503.1060918-1-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-Rspamd-Queue-Id: 913A040012 X-Stat-Signature: 563fddi8j5d4gdft17mq355ig89fxgzi X-Rspam-User: X-Rspamd-Server: rspam02 X-HE-Tag: 1785161157-258645 X-HE-Meta: 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 e/+DheOg 5fYL40Cb5jDznDEgri54ORxiic8FlkAySC9Jdr+nFFBPLHdVofEVMFtoytjIaInK99LWZgN+pW9JAqPeUv7P+ddYlt1MtoaIsEyrIkTrcuLThYikUXZKBNuj8b7GoOpHIrJoFzqSShf05XfjdAgwko4LBAc4oJcTGTrUmtI8sxGh9nRoBoKVR/nC7ubBAoSWTziwh6VV1q+FVuN3AAII75zQWh+cs3+eNSTtznUrygkGjMvPvGTBD/C16YgFsQUBFsqUxylo5qMANmWzwGmUjXvBT86wodVjtqFLPm5voJuC78v5v92CzgPN8K2I/gjj4JoGeiylD78UwHsf9NROnK1OP3Q== 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 | 51 +++++++++++++++++++++++++++++++++++++++++++++------ 1 file changed, 45 insertions(+), 6 deletions(-) diff --git a/mm/swapfile.c b/mm/swapfile.c index e0f5fe64de2a..7613ce231d70 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -3776,6 +3776,23 @@ 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) { @@ -3785,21 +3802,43 @@ 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; if (vm_start >= vm_end) 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); + } /* * Pairs with READ_ONCE() in shrink/grow paths. */ -- 2.54.0