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=-5.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable 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 36FD8C3A5A0 for ; Mon, 20 Apr 2020 19:51:46 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 06D442084D for ; Mon, 20 Apr 2020 19:51:45 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 06D442084D Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=stgolabs.net Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 8AE568E0005; Mon, 20 Apr 2020 15:51:45 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 85E678E0003; Mon, 20 Apr 2020 15:51:45 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 773AE8E0005; Mon, 20 Apr 2020 15:51:45 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0216.hostedemail.com [216.40.44.216]) by kanga.kvack.org (Postfix) with ESMTP id 5C03D8E0003 for ; Mon, 20 Apr 2020 15:51:45 -0400 (EDT) Received: from smtpin15.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id 1371E8245571 for ; Mon, 20 Apr 2020 19:51:45 +0000 (UTC) X-FDA: 76729278570.15.book27_2c517def4b862 X-HE-Tag: book27_2c517def4b862 X-Filterd-Recvd-Size: 3041 Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) by imf46.hostedemail.com (Postfix) with ESMTP for ; Mon, 20 Apr 2020 19:51:44 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id 42D0CAC20; Mon, 20 Apr 2020 19:51:41 +0000 (UTC) Date: Mon, 20 Apr 2020 12:48:13 -0700 From: Davidlohr Bueso To: Michel Lespinasse Cc: Andrew Morton , linux-mm , LKML , Peter Zijlstra , Laurent Dufour , Vlastimil Babka , Matthew Wilcox , Liam Howlett , Jerome Glisse , David Rientjes , Hugh Dickins , Ying Han , Jason Gunthorpe , Daniel Jordan Subject: Re: [PATCH v4 01/10] mmap locking API: initial implementation as rwsem wrappers Message-ID: <20200420194813.v7m7tmqhuza6qzoi@linux-p48b> Mail-Followup-To: Michel Lespinasse , Andrew Morton , linux-mm , LKML , Peter Zijlstra , Laurent Dufour , Vlastimil Babka , Matthew Wilcox , Liam Howlett , Jerome Glisse , David Rientjes , Hugh Dickins , Ying Han , Jason Gunthorpe , Daniel Jordan References: <20200415004353.130248-1-walken@google.com> <20200415004353.130248-2-walken@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: <20200415004353.130248-2-walken@google.com> User-Agent: NeoMutt/20180716 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: On Tue, 14 Apr 2020, Michel Lespinasse wrote: >This change wraps the existing mmap_sem related rwsem calls into a new >mmap locking API. There are two justifications for the new API: > >- At first, it provides an easy hooking point to instrument mmap_sem > locking latencies independently of any other rwsems. > >- In the future, it may be a starting point for replacing the rwsem > implementation with a different one, such as range locks. > >Signed-off-by: Michel Lespinasse >Reviewed-by: Daniel Jordan Reviewed-by: Davidlohr Bueso With one observation below. >+static inline void mmap_downgrade_write_lock(struct mm_struct *mm) >+{ >+ downgrade_write(&mm->mmap_sem); >+} Shouldn't this really be just mmap_downgrade_write()? In locking normally don't add the _lock at the end as it implies the operation of acquiring the lock. Thanks, Davidlohr