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 X-Spam-Level: X-Spam-Status: No, score=-3.7 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3D0DBC352A2 for ; Fri, 7 Feb 2020 13:17:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 14270218AC for ; Fri, 7 Feb 2020 13:17:56 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=shutemov-name.20150623.gappssmtp.com header.i=@shutemov-name.20150623.gappssmtp.com header.b="zXiaaJaV" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727018AbgBGNRz (ORCPT ); Fri, 7 Feb 2020 08:17:55 -0500 Received: from mail-lj1-f196.google.com ([209.85.208.196]:35651 "EHLO mail-lj1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727129AbgBGNRy (ORCPT ); Fri, 7 Feb 2020 08:17:54 -0500 Received: by mail-lj1-f196.google.com with SMTP id q8so2120154ljb.2 for ; Fri, 07 Feb 2020 05:17:51 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=shutemov-name.20150623.gappssmtp.com; s=20150623; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=ormWsvlEB3xaoLQJ32yqI2+YJjynCIo+Gkrsb90CUoc=; b=zXiaaJaV/6vtSOmP9ODS2FF3enQ9DrLr2xaXqFISXdgWNN7JEZGqqteYAJg8ilecHC ugo7pUkEj4BeIf0kvvpCo+9nvJTidcqrfgAKlXwcZrT/G25Hc0OKXxZ/73AFix6/STWU kzL1F0LE/LTZEKILuppx9YGI01N+5ZbDcEQGL0HvU+uZcMgWGZCPrEAiaZ+BllPyAS7f imqyuyZC2NI4FLBEhH4BIw6rEMsgDbGkg9nOxXihh8ryQwuUgPpw2KkNvbQrfWBn7wd+ mDYhZSynO7JxUG39HhOZIVunHOvL6zWKn3v9WqBVZysmR4JglhGrT7lyZay33uwkGfhZ Lp9g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=ormWsvlEB3xaoLQJ32yqI2+YJjynCIo+Gkrsb90CUoc=; b=QUUN+1JDQfQcNDVv7y95KNqeIsJvapyfXKAj4jVsT+2ysc2lk5N993PhjjFDoYnLED UF/dufdwUjzZqn9AjWzFpeznwkrZqffYJ2MkSrcfljWfiULB7RajldaFq9RetsnKM0WH JmKHYQvHdq5CPJKJudONPcznU/jrtB8Po3VPuZxDULzYylYoiAW8AJ+CJoEbtb64+N6T dC6brm1lmYDNwBjDC4RqBS5TDOhhaC0W739fzWXqlfMVCpOpV7eNW4Kjl3A8o3nk6HNL v2aOR8GMg6CorjCRVqv1RO1aqpmpcqEG+bo9k2SGTyzH8nmEFzy2AkgHQsXH67E4jfEb Keww== X-Gm-Message-State: APjAAAXe4r884i8R6W8onZdCCDnl6J6TjehvgGtOjJzxWf47n7QNNR61 dSytrbIrYmPSS+BqBCGgXx5rLg== X-Google-Smtp-Source: APXvYqxpnU/YqzHLLTtDrHtrmgEZwjR2XCzlQQy/QlYwTJZA8pqDeflD/7gMq3smNNvvvq1H14aHzw== X-Received: by 2002:a2e:7818:: with SMTP id t24mr5296927ljc.195.1581081470799; Fri, 07 Feb 2020 05:17:50 -0800 (PST) Received: from box.localdomain ([86.57.175.117]) by smtp.gmail.com with ESMTPSA id 3sm1236687lja.65.2020.02.07.05.17.49 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 07 Feb 2020 05:17:49 -0800 (PST) Received: by box.localdomain (Postfix, from userid 1000) id 623C7100B12; Fri, 7 Feb 2020 16:18:06 +0300 (+03) Date: Fri, 7 Feb 2020 16:18:06 +0300 From: "Kirill A. Shutemov" To: John Hubbard Cc: Andrew Morton , Al Viro , Christoph Hellwig , Dan Williams , Dave Chinner , Ira Weiny , Jan Kara , Jason Gunthorpe , Jonathan Corbet , =?utf-8?B?SsOpcsO0bWU=?= Glisse , Michal Hocko , Mike Kravetz , Shuah Khan , Vlastimil Babka , Matthew Wilcox , linux-doc@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-rdma@vger.kernel.org, linux-mm@kvack.org, LKML Subject: Re: [PATCH v5 04/12] mm: introduce page_ref_sub_return() Message-ID: <20200207131806.xwnhxomxgt3hoqcc@box> References: <20200207033735.308000-1-jhubbard@nvidia.com> <20200207033735.308000-5-jhubbard@nvidia.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200207033735.308000-5-jhubbard@nvidia.com> Sender: linux-rdma-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-rdma@vger.kernel.org On Thu, Feb 06, 2020 at 07:37:27PM -0800, John Hubbard wrote: > 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. > > Reviewed-by: Jan Kara > Signed-off-by: John Hubbard Acked-by: Kirill A. Shutemov -- Kirill A. Shutemov