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=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 48F12ECE58E for ; Mon, 7 Oct 2019 16:34:47 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 193602067B for ; Mon, 7 Oct 2019 16:34:46 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 193602067B Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 949F08E0006; Mon, 7 Oct 2019 12:34:46 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 8FB018E0003; Mon, 7 Oct 2019 12:34:46 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 8112B8E0006; Mon, 7 Oct 2019 12:34:46 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0226.hostedemail.com [216.40.44.226]) by kanga.kvack.org (Postfix) with ESMTP id 5EF458E0003 for ; Mon, 7 Oct 2019 12:34:46 -0400 (EDT) Received: from smtpin27.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with SMTP id 0A00D40E8 for ; Mon, 7 Oct 2019 16:34:46 +0000 (UTC) X-FDA: 76017537372.27.horse20_c7a3e1d9ba11 X-HE-Tag: horse20_c7a3e1d9ba11 X-Filterd-Recvd-Size: 3148 Received: from mx1.suse.de (mx2.suse.de [195.135.220.15]) by imf19.hostedemail.com (Postfix) with ESMTP for ; Mon, 7 Oct 2019 16:34:45 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 5BB49AC8B; Mon, 7 Oct 2019 16:34:44 +0000 (UTC) Date: Mon, 7 Oct 2019 18:34:43 +0200 From: Daniel Wagner To: Uladzislau Rezki Cc: Sebastian Andrzej Siewior , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-rt-users@vger.kernel.org, Andrew Morton Subject: Re: [PATCH] mm: vmalloc: Use the vmap_area_lock to protect ne_fit_preload_node Message-ID: <20191007163443.6owts5jp2frum7cy@beryllium.lan> References: <20191003090906.1261-1-dwagner@suse.de> <20191004153728.c5xppuqwqcwecbe6@linutronix.de> <20191004162041.GA30806@pc636> <20191004163042.jpiau6dlxqylbpfh@linutronix.de> <20191007083037.zu3n5gindvo7damg@beryllium.lan> <20191007105631.iau6zhxqjeuzajnt@linutronix.de> <20191007162330.GA26503@pc636> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191007162330.GA26503@pc636> User-Agent: NeoMutt/20180716 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000003, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Mon, Oct 07, 2019 at 06:23:30PM +0200, Uladzislau Rezki wrote: > Hello, Daniel, Sebastian. > > > > On Fri, Oct 04, 2019 at 06:30:42PM +0200, Sebastian Andrzej Siewior wrote: > > > > On 2019-10-04 18:20:41 [+0200], Uladzislau Rezki wrote: > > > > > If we have migrate_disable/enable, then, i think preempt_enable/disable > > > > > should be replaced by it and not the way how it has been proposed > > > > > in the patch. > > > > > > > > I don't think this patch is appropriate for upstream. > > > > > > Yes, I agree. The discussion made this clear, this is only for -rt > > > trees. Initially I though this should be in mainline too. > > > > Sorry, this was _before_ Uladzislau pointed out that you *just* moved > > the lock that was there from the beginning. I missed that while looking > > over the patch. Based on that I don't think that this patch is not > > appropriate for upstream. > > > Yes that is a bit messy :) Then i do not see what that patch fixes in > mainline? Instead it will just add an extra blocking, i did not want that > therefore used preempt_enable/disable. But, when i saw this patch i got it > as a preparation of PREEMPT_RT merging work. Maybe I should add some background info here as well. Currently, I am creating an -rt tree on v5.3 for which I need this patch (or a migrate_disable() version of it). So this is slightly independent of the work Sebiastian is doing. Though the mainline effort of PREEMPT_RT will hit this problem as well. I understood Sebiastian wrong above. I thought he suggest to use the migrate_disable() approach even for mainline. I supppose, one thing which would help in this discussion, is what do you gain by using preempt_disable() instead of moving the lock up? Do you have performance numbers which could justify the code?