From patchwork Thu Apr 2 04:05:18 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Andrew Morton X-Patchwork-Id: 11469877 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 5E76D92A for ; Thu, 2 Apr 2020 04:05:22 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 221632078B for ; Thu, 2 Apr 2020 04:05:22 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="sauyYYRL" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 221632078B Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 133DC8E0028; Thu, 2 Apr 2020 00:05:21 -0400 (EDT) Delivered-To: linux-mm-outgoing@kvack.org Received: by kanga.kvack.org (Postfix, from userid 40) id 10D0A8E000D; Thu, 2 Apr 2020 00:05:21 -0400 (EDT) X-Original-To: int-list-linux-mm@kvack.org X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 04D488E0028; Thu, 2 Apr 2020 00:05:20 -0400 (EDT) X-Original-To: linux-mm@kvack.org X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0090.hostedemail.com [216.40.44.90]) by kanga.kvack.org (Postfix) with ESMTP id D6F458E000D for ; Thu, 2 Apr 2020 00:05:20 -0400 (EDT) Received: from smtpin28.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id 95FAB180AD80F for ; Thu, 2 Apr 2020 04:05:20 +0000 (UTC) X-FDA: 76661575200.28.rate80_2e9afc6613514 X-Spam-Summary: 2,0,0,bff915a3f2f54713,d41d8cd98f00b204,akpm@linux-foundation.org,,RULES_HIT:41:152:355:379:800:960:967:973:988:989:1260:1263:1277:1311:1313:1314:1345:1359:1381:1431:1437:1513:1515:1516:1518:1521:1534:1542:1593:1594:1711:1730:1747:1777:1792:2198:2199:2393:2525:2553:2559:2563:2682:2685:2859:2902:2933:2937:2939:2942:2945:2947:2951:2954:3022:3138:3139:3140:3141:3142:3352:3865:3866:3867:3868:3871:3872:3874:3934:3936:3938:3941:3944:3947:3950:3953:3956:3959:4321:5007:6261:6653:6737:7576:8599:9025:9545:10004:10400:10913:11026:11658:11914:12043:12048:12114:12297:12438:12517:12519:12555:12679:12783:12986:13846:14093:14097:14181:14721:14849:21080:21325:21451:21611:21627:21939:21990:30054:30064:30070:30090,0,RBL:198.145.29.99:@linux-foundation.org:.lbl8.mailshell.net-62.2.0.100 64.100.201.201,CacheIP:none,Bayesian:0.5,0.5,0.5,Netcheck:none,DomainCache:0,MSF:not bulk,SPF:fp,MSBL:0,DNSBL:neutral,Custom_rules:0:0:0,LFtime:2,LUA_SUMMARY:none X-HE-Tag: rate80_2e9afc6613514 X-Filterd-Recvd-Size: 3803 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf48.hostedemail.com (Postfix) with ESMTP for ; Thu, 2 Apr 2020 04:05:20 +0000 (UTC) Received: from localhost.localdomain (c-73-231-172-41.hsd1.ca.comcast.net [73.231.172.41]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id C116220784; Thu, 2 Apr 2020 04:05:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1585800319; bh=6gpJXWdBT0OV9ZFUCDG8rPypgrfPoy4LsmI6aQX/6H0=; h=Date:From:To:Subject:In-Reply-To:From; b=sauyYYRLZa/r1zo04++T2EAnanmbVI+K+QVimhS7LzN5QAfQqXNGfdTcXqtKhQmMu 2IfWFF4eV1eLcW/+ghzhl08sItOyKPWVyQJDY2Xg8OlodoiA0+74spiOsSUnZ7tPRM xEHR/m/Nvwbl2wzXCCL75rVgonZlEmAX4oVr+Et4= Date: Wed, 01 Apr 2020 21:05:18 -0700 From: Andrew Morton To: akpm@linux-foundation.org, corbet@lwn.net, dan.j.williams@intel.com, david@fromorbit.com, hch@infradead.org, ira.weiny@intel.com, jack@suse.cz, jgg@ziepe.ca, jglisse@redhat.com, jhubbard@nvidia.com, kirill.shutemov@linux.intel.com, linux-mm@kvack.org, mhocko@suse.com, mike.kravetz@oracle.com, mm-commits@vger.kernel.org, shuah@kernel.org, torvalds@linux-foundation.org, vbabka@suse.cz, viro@zeniv.linux.org.uk, willy@infradead.org Subject: [patch 040/155] mm: introduce page_ref_sub_return() Message-ID: <20200402040518.lEoJTr-YH%akpm@linux-foundation.org> In-Reply-To: <20200401210155.09e3b9742e1c6e732f5a7250@linux-foundation.org> User-Agent: s-nail v14.8.16 MIME-Version: 1.0 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: From: John Hubbard Subject: mm: introduce page_ref_sub_return() An upcoming patch requires subtracting a large chunk of refcounts from a page, and checking what the resulting refcount is. This is a little different than the usual "check for zero refcount" that many of the page ref functions already do. However, it is similar to a few other routines that (like this one) are generally useful for things such as 1-based refcounting. Add page_ref_sub_return(), that subtracts a chunk of refcounts atomically, and returns an atomic snapshot of the result. Link: http://lkml.kernel.org/r/20200211001536.1027652-4-jhubbard@nvidia.com Signed-off-by: John Hubbard Reviewed-by: Jan Kara Acked-by: Kirill A. Shutemov Cc: Ira Weiny Cc: Jérôme Glisse Cc: "Matthew Wilcox (Oracle)" Cc: Al Viro Cc: Christoph Hellwig Cc: Dan Williams Cc: Dave Chinner Cc: Jason Gunthorpe Cc: Jonathan Corbet Cc: Michal Hocko Cc: Mike Kravetz Cc: Shuah Khan Cc: Vlastimil Babka Signed-off-by: Andrew Morton --- include/linux/page_ref.h | 9 +++++++++ 1 file changed, 9 insertions(+) --- a/include/linux/page_ref.h~mm-introduce-page_ref_sub_return +++ a/include/linux/page_ref.h @@ -102,6 +102,15 @@ static inline void page_ref_sub(struct p __page_ref_mod(page, -nr); } +static inline int page_ref_sub_return(struct page *page, int nr) +{ + int ret = atomic_sub_return(nr, &page->_refcount); + + if (page_ref_tracepoint_active(__tracepoint_page_ref_mod_and_return)) + __page_ref_mod_and_return(page, -nr, ret); + return ret; +} + static inline void page_ref_inc(struct page *page) { atomic_inc(&page->_refcount);