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=-8.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 AFA24C2D0A8 for ; Wed, 23 Sep 2020 14:33:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 782F5206FB for ; Wed, 23 Sep 2020 14:33:25 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="pA5Hd7/w"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="qGRiwr69" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726709AbgIWOdV (ORCPT ); Wed, 23 Sep 2020 10:33:21 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33960 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726587AbgIWOdV (ORCPT ); Wed, 23 Sep 2020 10:33:21 -0400 Received: from galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7B8F9C0613CE; Wed, 23 Sep 2020 07:33:21 -0700 (PDT) From: Thomas Gleixner DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1600871599; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=htFCLJWsNhxoKbCNWhQS/6Kyz86LUNNWBiBq6qkBFyQ=; b=pA5Hd7/wYPJW36CTtNNTbOYCzRvXBsTbhCHBjjmQZ01hpagIyv/VcnxLW17kJqMxHoJumz z5+hv3BrOqb8U7x+bnWe3Vg7hjpdsIzhk0Jj3S1z+5+winumEs8KsUyf1K1TnGwBajSWcB LPdDuPzlUY6BQkUL/KCzLAeEkhIHNDaswPGDWAOJny+dzcHlZahNl7c2FSd1xp6gP0rEgj KzUlj0Dxhw0txRUSLaqWlErEiWSU9Sozf2/yRD5Qwp08ro8Q2KjAE/20gQBa42apztEBT8 SUzGb5WlY8s1AJc0khV/84NW02EhLXtT8nMIfQBdpZd1EmcFI7Hj8Ky6D6u98A== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1600871599; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=htFCLJWsNhxoKbCNWhQS/6Kyz86LUNNWBiBq6qkBFyQ=; b=qGRiwr69/8k8ntlbQpv0icecJVUI4PbZN1b5MTw/xOk+gHpAMJmHhEqUxn40L21XWDImxq PUiJwewr0xn47MAg== To: Linus Torvalds Cc: LKML , linux-arch , Paul McKenney , the arch/x86 maintainers , Sebastian Andrzej Siewior , Peter Zijlstra , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Daniel Bristot de Oliveira , Will Deacon , Andrew Morton , Linux-MM , Russell King , Linux ARM , Chris Zankel , Max Filippov , linux-xtensa@linux-xtensa.org, Jani Nikula , Joonas Lahtinen , Rodrigo Vivi , David Airlie , Daniel Vetter , intel-gfx , dri-devel , Ard Biesheuvel , Herbert Xu , Vineet Gupta , "open list\:SYNOPSYS ARC ARCHITECTURE" , Arnd Bergmann , Guo Ren , linux-csky@vger.kernel.org, Michal Simek , Thomas Bogendoerfer , linux-mips@vger.kernel.org, Nick Hu , Greentime Hu , Vincent Chen , Michael Ellerman , Benjamin Herrenschmidt , Paul Mackerras , linuxppc-dev , "David S. Miller" , linux-sparc Subject: Re: [patch RFC 00/15] mm/highmem: Provide a preemptible variant of kmap_atomic & friends In-Reply-To: <87sgbbaq0y.fsf@nanos.tec.linutronix.de> References: <20200919091751.011116649@linutronix.de> <87mu1lc5mp.fsf@nanos.tec.linutronix.de> <87k0wode9a.fsf@nanos.tec.linutronix.de> <87eemwcpnq.fsf@nanos.tec.linutronix.de> <87a6xjd1dw.fsf@nanos.tec.linutronix.de> <87sgbbaq0y.fsf@nanos.tec.linutronix.de> Date: Wed, 23 Sep 2020 16:33:19 +0200 Message-ID: <877dska7gw.fsf@nanos.tec.linutronix.de> MIME-Version: 1.0 Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: linux-csky@vger.kernel.org On Mon, Sep 21 2020 at 21:27, Thomas Gleixner wrote: > On Mon, Sep 21 2020 at 09:24, Linus Torvalds wrote: >> On Mon, Sep 21, 2020 at 12:39 AM Thomas Gleixner wrote: >> Maybe we really *could* call this new kmap functionality something >> like "kmap_percpu()" (or maybe "local" is good enough), and make it >> act like your RT code does for spinlocks - not disable preemption, but >> only disabling CPU migration. > > I"m all for it, but the scheduler people have opinions :) I just took the latest version of migrate disable patches https://lore.kernel.org/r/20200921163557.234036895@infradead.org removed the RT dependency on top of them and adopted the kmap stuff (addressing the various comments while at it and unbreaking ARM). I'm not going to post that until there is consensus about the general availability of migrate disable, but for those who want to play with it I've pushed the resulting combo out to: git://git.kernel.org/pub/scm/linux/kernel/git/tglx/devel.git highmem For testing I've tweaked a few places to use the new _local() variants and it survived testing so far and I've verified that there is actual preemption which means zap/restore of the thread local kmaps. Thanks, tglx