From patchwork Wed Nov 9 20:30:49 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Linus Torvalds X-Patchwork-Id: 13038033 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 70131C433FE for ; Wed, 9 Nov 2022 20:31:01 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 0747F6B0074; Wed, 9 Nov 2022 15:31:01 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 04C246B0075; Wed, 9 Nov 2022 15:31:00 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id E55AD6B0078; Wed, 9 Nov 2022 15:31:00 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id D5E586B0074 for ; Wed, 9 Nov 2022 15:31:00 -0500 (EST) Received: from smtpin20.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay08.hostedemail.com (Postfix) with ESMTP id AD803140797 for ; Wed, 9 Nov 2022 20:31:00 +0000 (UTC) X-FDA: 80115047880.20.4C5CFB9 Received: from sin.source.kernel.org (sin.source.kernel.org [145.40.73.55]) by imf04.hostedemail.com (Postfix) with ESMTP id 6BF5E4000D for ; Wed, 9 Nov 2022 20:30:58 +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 sin.source.kernel.org (Postfix) with ESMTPS id D8F5DCE206D; Wed, 9 Nov 2022 20:30:55 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id EFF72C433D6; Wed, 9 Nov 2022 20:30:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1668025854; bh=jfWc6kn68kAyUZF8S+7X4sveku1vOvDNUz/xy6wAir4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=xAEEZ1gj7l/8wAdz869fjwgcq9wqP+Dk9DLHIoqpv7MpspKrUddN8gJBa9flxuM9G Vrz2Zp2MCnXa6CWwwcVkFSlbSQHlIrFSXzHlH1b8ADAoxLYHHvXiB9fJOStTLi+dBv CJTPJDnlQrjEPOrNEJgV2mPcJCmjITlERtnVSK7U= 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: Wed, 9 Nov 2022 12:30:49 -0800 Message-Id: <20221109203051.1835763-2-torvalds@linux-foundation.org> X-Mailer: git-send-email 2.38.1.284.gfd9468d787 In-Reply-To: <20221109203051.1835763-1-torvalds@linux-foundation.org> References: <20221109203051.1835763-1-torvalds@linux-foundation.org> MIME-Version: 1.0 ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1668025860; 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=UkzXwuIPer6m1qfUHwUxQj1lq9ihfcZ5svVTS/LLtro=; b=QbRLUpzxyurkbws9qseD3v1z2oMzgwl8T4POJMox+F+AnjFMeIQVBPiiun7+U1nC3613sn +yUISwqKY2qsPpccDS9v1ZI7T06GIakBSknDOYvSe+fShmY2HyQ75gIaUN+Gn57gIwd7YL AVAAvyqLr5f0azpaLm7ShJTXCl1XUtU= ARC-Authentication-Results: i=1; imf04.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=korg header.b=xAEEZ1gj; spf=pass (imf04.hostedemail.com: domain of torvalds@linux-foundation.org designates 145.40.73.55 as permitted sender) smtp.mailfrom=torvalds@linux-foundation.org; dmarc=none ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1668025860; a=rsa-sha256; cv=none; b=bwcbOJipW3UlRQE61sfxjf8B4OpvvlD3GDC0wXoRkjtp3dxkPsabrxGQCz74skBuYk58EC WHz6AWM9ZZZAPv2NfNzGQhamBF22DkLpnn2vuoRUnVTRA3Ewii7xRazBD051G5kLMeMsAU 2SuQ8Hmb6cMhZBtXaZtbocnBZikcWMc= X-Rspamd-Queue-Id: 6BF5E4000D X-Rspam-User: X-Rspamd-Server: rspam08 Authentication-Results: imf04.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=korg header.b=xAEEZ1gj; spf=pass (imf04.hostedemail.com: domain of torvalds@linux-foundation.org designates 145.40.73.55 as permitted sender) smtp.mailfrom=torvalds@linux-foundation.org; dmarc=none X-Stat-Signature: c5u4zdkqw4384xz6hsir3huj465rwz7f X-HE-Tag: 1668025858-701520 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. Acked-by: Johannes Weiner Acked-by: Hugh Dickins Signed-off-by: Linus Torvalds Reviewed-by: David Hildenbrand --- 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