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=2.2 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, UNWANTED_LANGUAGE_BODY 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 3C2A3C43331 for ; Wed, 1 Apr 2020 13:42:45 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 007AD2073B for ; Wed, 1 Apr 2020 13:42:44 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="kwi78sSE" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 007AD2073B Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 8C2FD8E0005; Wed, 1 Apr 2020 09:42:44 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 872898E0001; Wed, 1 Apr 2020 09:42:44 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 788438E0005; Wed, 1 Apr 2020 09:42:44 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0025.hostedemail.com [216.40.44.25]) by kanga.kvack.org (Postfix) with ESMTP id 601508E0001 for ; Wed, 1 Apr 2020 09:42:44 -0400 (EDT) Received: from smtpin14.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 2083F2479 for ; Wed, 1 Apr 2020 13:42:44 +0000 (UTC) X-FDA: 76659401448.14.pie57_520c1c671b828 X-HE-Tag: pie57_520c1c671b828 X-Filterd-Recvd-Size: 3145 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) by imf37.hostedemail.com (Postfix) with ESMTP for ; Wed, 1 Apr 2020 13:42:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=phd5kLezoWzhv+zq6NfHJxhtn1HcBOvVhCX2VSrRkwI=; b=kwi78sSEhcSExLqgEM42sBDLP2 pymfreP9aKaw+oPmxQyAOGWC55oHYud4NULSY/XurHbnuAp8qqAlk7lvIUxQKGdF30AmrIKwnhlc3 OLHaY05QFmREqtXPAiOcJE+URAvKhhoRVREtM58NP8tF7flo4NioCtJiCsjSVAZ8mCIBRPlLdKxJn lAXwH06dgYnsGmeWHUOGRD4rjDVv2e2Ap9WCwVQfJHRwOO/ABMi23/05faNVhZCatw4g1NYu1DHqN 575/s7NZ4WC2DHxKJs4MrJkCfPWwZQuAgXli0l5Bo0fRDYQjvLgK2izGf9QbGz/Iu1lb4bpfcdm+h 5oOpQP3g==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by bombadil.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1jJddd-0004vK-Uh; Wed, 01 Apr 2020 13:42:38 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 2496C3025C3; Wed, 1 Apr 2020 15:42:35 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 0876B29D8616E; Wed, 1 Apr 2020 15:42:35 +0200 (CEST) Date: Wed, 1 Apr 2020 15:42:34 +0200 From: Peter Zijlstra To: Michel Lespinasse Cc: Andrew Morton , linux-mm , LKML , Laurent Dufour , Vlastimil Babka , Matthew Wilcox , Liam Howlett , Jerome Glisse , Davidlohr Bueso , David Rientjes , Hugh Dickins , Ying Han , Jason Gunthorpe , Markus Elfring Subject: Re: [PATCH v3 06/10] mmap locking API: convert nested write lock sites Message-ID: <20200401134234.GR20696@hirez.programming.kicks-ass.net> References: <20200327225102.25061-1-walken@google.com> <20200327225102.25061-7-walken@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200327225102.25061-7-walken@google.com> 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 Fri, Mar 27, 2020 at 03:50:58PM -0700, Michel Lespinasse wrote: > @@ -26,6 +31,12 @@ static inline void mmap_write_unlock(struct mm_struct *mm) > up_write(&mm->mmap_sem); > } > > +/* Pairs with mmap_write_lock_nested() */ > +static inline void mmap_write_unlock_nested(struct mm_struct *mm) > +{ > + up_write(&mm->mmap_sem); > +} > + > static inline void mmap_downgrade_write_lock(struct mm_struct *mm) > { > downgrade_write(&mm->mmap_sem); Why does unlock_nested() make sense ?