From patchwork Tue Nov 8 19:41:37 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Linus Torvalds X-Patchwork-Id: 13036781 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]) by smtp.lore.kernel.org (Postfix) with ESMTP id F2C7AC4332F for ; Tue, 8 Nov 2022 19:41:43 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 3E7588E0003; Tue, 8 Nov 2022 14:41:43 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 397648E0001; Tue, 8 Nov 2022 14:41:43 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 25FDA8E0003; Tue, 8 Nov 2022 14:41:43 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0014.hostedemail.com [216.40.44.14]) by kanga.kvack.org (Postfix) with ESMTP id 134998E0001 for ; Tue, 8 Nov 2022 14:41:43 -0500 (EST) Received: from smtpin29.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay01.hostedemail.com (Postfix) with ESMTP id A15F21C6B46 for ; Tue, 8 Nov 2022 19:41:42 +0000 (UTC) X-FDA: 80111294844.29.5C398AB Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by imf04.hostedemail.com (Postfix) with ESMTP id 2419340003 for ; Tue, 8 Nov 2022 19:41:41 +0000 (UTC) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 5195261779; Tue, 8 Nov 2022 19:41:41 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8D899C433D7; Tue, 8 Nov 2022 19:41:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1667936500; bh=bgbt2enUCqI8iRJ3RLKDZTlxwyLbgJ8OtsM1oeqQotc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=yqjVAyZd9QMNx7zvF9RtUrYl2DUpE3QM9v79JHlipIOyabYoezYTfg7mvFoKlO5HA u+Be86X/jvDj085UDR3r30GnW1oO8qZQUTKVkgquJotczGNAYXFFbsqWbny7SRK37i dvVjGLO4A8tis77odWALXcqs8tdGEWCYKv256b/U= From: Linus Torvalds To: Hugh Dickins , Johannes Weiner , Andrew Morton Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: [PATCH 2/4] mm: teach release_pages() to take an array of encoded page pointers too Date: Tue, 8 Nov 2022 11:41:37 -0800 Message-Id: <20221108194139.57604-2-torvalds@linux-foundation.org> X-Mailer: git-send-email 2.38.1.284.gfd9468d787 In-Reply-To: References: MIME-Version: 1.0 ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1667936502; 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=Hmz0BPz5K3mm7/cFxcxshgj5LagSPu177E0OJnHGgRM=; b=CM1Wn84py5Y5zyvRiA18Ii+5G9ZGsAowUFhzfrnY1ULc1HDOQOhIqbQ6B7v1JFVoqrSEcG XmD2f0GRmKDQmB5iQL0Ij3MNHsmCYNXlUi1d+5CdCqVK7Rklk3+tEg7b7NygGGCoVwbqEa Eyu7lM/TiHZh0r/oxVF+S9XZFzJC/co= ARC-Authentication-Results: i=1; imf04.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=korg header.b=yqjVAyZd; spf=pass (imf04.hostedemail.com: domain of torvalds@linux-foundation.org designates 139.178.84.217 as permitted sender) smtp.mailfrom=torvalds@linux-foundation.org; dmarc=none ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1667936502; a=rsa-sha256; cv=none; b=gb2wctohfqqI4wh1GfyqIGe8VPBxvn8NUkTaRYjvY50S4q4h7aZzjSZIhXKeMg4JnjjSYv BZltpCAikcIW+1SSQTH6uGQzaagST9dMCY4IwV02bOmbPNKz1EK8Hs7gN7bL9rM5sQ+9Ea ylSyqPu5qGt21lNxSoUMrsyPhvhv/kQ= X-Rspamd-Queue-Id: 2419340003 Authentication-Results: imf04.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=korg header.b=yqjVAyZd; spf=pass (imf04.hostedemail.com: domain of torvalds@linux-foundation.org designates 139.178.84.217 as permitted sender) smtp.mailfrom=torvalds@linux-foundation.org; dmarc=none X-Rspamd-Server: rspam10 X-Rspam-User: X-Stat-Signature: f73kwuph799at35881w4xcqexn1udghf X-HE-Tag: 1667936501-241259 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: release_pages() already could take either an array of page pointers, or an array of folio pointers. Expand it to also accept an array of encoded page pointers, which is what both the existing mlock() use and the upcoming mmu_gather use of encoded page pointers wants. Note that release_pages() won't actually use, or react to, any extra encoded bits. Instead, this is very much a case of "I have walked the array of encoded pages and done everything the extra bits tell me to do, now release it all". Also, while the "either page or folio pointers" dual use was handled with a cast of the pointer in "release_folios()", this takes a slightly different approach and uses the "transparent union" attribute to describe the set of arguments to the function: https://gcc.gnu.org/onlinedocs/gcc/Common-Type-Attributes.html which has been supported by gcc forever, but the kernel hasn't used before. That allows us to avoid using various wrappers with casts, and just use the same function regardless of use. Signed-off-by: Linus Torvalds --- include/linux/mm.h | 21 +++++++++++++++++++-- mm/swap.c | 16 ++++++++++++---- 2 files changed, 31 insertions(+), 6 deletions(-) diff --git a/include/linux/mm.h b/include/linux/mm.h index 8bbcccbc5565..d9fb5c3e3045 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -1179,7 +1179,24 @@ static inline void folio_put_refs(struct folio *folio, int refs) __folio_put(folio); } -void release_pages(struct page **pages, int nr); +/** + * release_pages - release an array of pages or folios + * + * This just releases a simple array of multiple pages, and + * accepts various different forms of said page array: either + * a regular old boring array of pages, an array of folios, or + * an array of encoded page pointers. + * + * The transparent union syntax for this kind of "any of these + * argument types" is all kinds of ugly, so look away. + */ +typedef union { + struct page **pages; + struct folio **folios; + struct encoded_page **encoded_pages; +} release_pages_arg __attribute__ ((__transparent_union__)); + +void release_pages(release_pages_arg, int nr); /** * folios_put - Decrement the reference count on an array of folios. @@ -1195,7 +1212,7 @@ void release_pages(struct page **pages, int nr); */ static inline void folios_put(struct folio **folios, unsigned int nr) { - release_pages((struct page **)folios, nr); + release_pages(folios, nr); } static inline void put_page(struct page *page) diff --git a/mm/swap.c b/mm/swap.c index 955930f41d20..596ed226ddb8 100644 --- a/mm/swap.c +++ b/mm/swap.c @@ -968,22 +968,30 @@ void lru_cache_disable(void) /** * release_pages - batched put_page() - * @pages: array of pages to release + * @arg: array of pages to release * @nr: number of pages * - * Decrement the reference count on all the pages in @pages. If it + * Decrement the reference count on all the pages in @arg. If it * fell to zero, remove the page from the LRU and free it. + * + * Note that the argument can be an array of pages, encoded pages, + * or folio pointers. We ignore any encoded bits, and turn any of + * them into just a folio that gets free'd. */ -void release_pages(struct page **pages, int nr) +void release_pages(release_pages_arg arg, int nr) { int i; + struct encoded_page **encoded = arg.encoded_pages; LIST_HEAD(pages_to_free); struct lruvec *lruvec = NULL; unsigned long flags = 0; unsigned int lock_batch; for (i = 0; i < nr; i++) { - struct folio *folio = page_folio(pages[i]); + struct folio *folio; + + /* Turn any of the argument types into a folio */ + folio = page_folio(encoded_page_ptr(encoded[i])); /* * Make sure the IRQ-safe lock-holding time does not get