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 EE798ECE58C for ; Mon, 7 Oct 2019 16:34:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id BED352067B for ; Mon, 7 Oct 2019 16:34:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728019AbfJGQeq (ORCPT ); Mon, 7 Oct 2019 12:34:46 -0400 Received: from mx2.suse.de ([195.135.220.15]:50500 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727801AbfJGQeq (ORCPT ); Mon, 7 Oct 2019 12:34:46 -0400 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 Sender: linux-rt-users-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-rt-users@vger.kernel.org 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?