From patchwork Mon Jan 10 04:23:50 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Matthew Wilcox X-Patchwork-Id: 12708181 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 0D1E2C4332F for ; Mon, 10 Jan 2022 04:24:48 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id DFD296B0093; Sun, 9 Jan 2022 23:24:32 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id D83456B0096; Sun, 9 Jan 2022 23:24:32 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id C01886B0098; Sun, 9 Jan 2022 23:24:32 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0072.hostedemail.com [216.40.44.72]) by kanga.kvack.org (Postfix) with ESMTP id 9E5F36B0093 for ; Sun, 9 Jan 2022 23:24:32 -0500 (EST) Received: from smtpin21.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 5DCA493694 for ; Mon, 10 Jan 2022 04:24:32 +0000 (UTC) X-FDA: 79013085984.21.236D297 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) by imf10.hostedemail.com (Postfix) with ESMTP id 0CCB8C0005 for ; Mon, 10 Jan 2022 04:24:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=Content-Transfer-Encoding:MIME-Version: References:In-Reply-To:Message-Id:Date:Subject:Cc:To:From:Sender:Reply-To: Content-Type:Content-ID:Content-Description; bh=pr6dwM9p32xFGkENVfW8ccHIrI0fREnA+ZakTJ73Pp8=; b=diLvaBxsmnGNc0FH5T2NoqikDX Q4Ygnsy6APbDxF2yhgPg/bUDT/ZZl5VKG73fA3Wb/qUY1yr/6zw06e9ozJDWRpziaMw2g2IVFIu6U QnHwvyE3ecy9hBMdhQhrtNPVBoIQRVfVsI3wVBFTXIjA17sjB/F36yzkUY1r2uMTg8eCIyjpcgs9o HERYwayFGxgm8bF0MKu0UBGFNSiWSAGYzZjJQKryikGkg7Sgy50thISU/Y4S9hK8usWe9Zha3lydG neZjS1K3jtVAYFKarLfjPxhFpKfl6hIaB5iteXtDUv2QkKsgaiFuxpgj50rTbXDia0Jtfj3fRnA79 jjHXkc7g==; Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1n6mE8-0025wo-Pi; Mon, 10 Jan 2022 04:24:12 +0000 From: "Matthew Wilcox (Oracle)" To: linux-mm@kvack.org Cc: "Matthew Wilcox (Oracle)" , John Hubbard , Christoph Hellwig , William Kucharski , linux-kernel@vger.kernel.org, Jason Gunthorpe Subject: [PATCH v2 12/28] mm: Add folio_put_refs() Date: Mon, 10 Jan 2022 04:23:50 +0000 Message-Id: <20220110042406.499429-13-willy@infradead.org> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20220110042406.499429-1-willy@infradead.org> References: <20220110042406.499429-1-willy@infradead.org> MIME-Version: 1.0 X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 0CCB8C0005 X-Stat-Signature: f95rjwrkyahkrjs8f7zsekje6pjq99se Authentication-Results: imf10.hostedemail.com; dkim=pass header.d=infradead.org header.s=casper.20170209 header.b=diLvaBxs; dmarc=none; spf=none (imf10.hostedemail.com: domain of willy@infradead.org has no SPF policy when checking 90.155.50.34) smtp.mailfrom=willy@infradead.org X-HE-Tag: 1641788671-347042 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: This is like folio_put(), but puts N references at once instead of just one. It's like put_page_refs(), but does one atomic operation instead of two, and is available to more than just gup.c. Signed-off-by: Matthew Wilcox (Oracle) Reviewed-by: Christoph Hellwig Reviewed-by: John Hubbard --- include/linux/mm.h | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+) diff --git a/include/linux/mm.h b/include/linux/mm.h index 598be27d4d2e..bf9624ca61c3 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -1234,6 +1234,26 @@ static inline void folio_put(struct folio *folio) __put_page(&folio->page); } +/** + * folio_put_refs - Reduce the reference count on a folio. + * @folio: The folio. + * @refs: The number of references to reduce. + * + * If the folio's reference count reaches zero, the memory will be + * released back to the page allocator and may be used by another + * allocation immediately. Do not access the memory or the struct folio + * after calling folio_put_refs() unless you can be sure that these weren't + * the last references. + * + * Context: May be called in process or interrupt context, but not in NMI + * context. May be called while holding a spinlock. + */ +static inline void folio_put_refs(struct folio *folio, int refs) +{ + if (folio_ref_sub_and_test(folio, refs)) + __put_page(&folio->page); +} + static inline void put_page(struct page *page) { struct folio *folio = page_folio(page);