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=-0.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS 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 1EE3DFC6194 for ; Fri, 8 Nov 2019 03:22:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E916221882 for ; Fri, 8 Nov 2019 03:22:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1573183329; bh=TtcIWVFvH8sO1mq2610KXVS5GHlyLmK8WHMed4U9AGE=; h=Date:From:To:Cc:Subject:In-Reply-To:References:List-ID:From; b=dZEd1BZ65c7BEqXVfLtC9WuUitVqbcm9QMbbYYz/ejgjmDCvQKY3DcYRKAF6CFc+I U4JZa8P3u6b0OwgYu/WScWKwYICJ0yKEzWYQE9KXykijiu7HSvsMdRqThHQCmlBz4m 21EH6AeTVhma+fcBdhvCIKOKOEGq3safxezz8L7U= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729219AbfKHDWH (ORCPT ); Thu, 7 Nov 2019 22:22:07 -0500 Received: from mail.kernel.org ([198.145.29.99]:37540 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726094AbfKHDWH (ORCPT ); Thu, 7 Nov 2019 22:22:07 -0500 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 5786D2084D; Fri, 8 Nov 2019 03:22:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1573183325; bh=TtcIWVFvH8sO1mq2610KXVS5GHlyLmK8WHMed4U9AGE=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=goM3px9yVWQf4lLKGGqGOlhfcK257j/88y22lMvV/faxJTGgCRbxIR8rGfQ5CGTIi TIA7RiicdBJaz8LkMEIljlJGPwo9VhlEl2Wt45XF5wMI7vFupjlApXz/vFhXW1ujnA 7tioyhL0YMkILin71mygpOcnIGD90V0T2nbXh7zs= Date: Thu, 7 Nov 2019 19:22:02 -0800 From: Andrew Morton To: Davidlohr Bueso Cc: Mike Kravetz , Matthew Wilcox , Waiman Long , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Peter Zijlstra , Ingo Molnar , Will Deacon Subject: Re: [PATCH] hugetlbfs: Take read_lock on i_mmap for PMD sharing Message-Id: <20191107192202.8869589f225132480d77a33b@linux-foundation.org> In-Reply-To: <20191108020456.sulyjskhq3s5zcaa@linux-p48b> References: <20191107190628.22667-1-longman@redhat.com> <20191107195441.GF11823@bombadil.infradead.org> <20191108020456.sulyjskhq3s5zcaa@linux-p48b> X-Mailer: Sylpheed 3.5.1 (GTK+ 2.24.31; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 7 Nov 2019 18:04:56 -0800 Davidlohr Bueso wrote: > On Thu, 07 Nov 2019, Mike Kravetz wrote: > > >Note that huge_pmd_share now increments the page count with the semaphore > >held just in read mode. It is OK to do increments in parallel without > >synchronization. However, we don't want anyone else changing the count > >while that check in huge_pmd_unshare is happening. Hence, the need for > >taking the semaphore in write mode. > > This would be a nice addition to the changelog methinks. Done.