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=-3.5 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED 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 16991C43469 for ; Mon, 21 Sep 2020 07:35:15 +0000 (UTC) Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id C290C2158C for ; Mon, 21 Sep 2020 07:35:14 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="tzqY9X8f"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="Ajg419VR" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C290C2158C Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linutronix.de Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=dri-devel-bounces@lists.freedesktop.org Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 7EB126E217; Mon, 21 Sep 2020 07:35:00 +0000 (UTC) Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) by gabe.freedesktop.org (Postfix) with ESMTPS id 66AF36E0CA; Sun, 20 Sep 2020 17:24:52 +0000 (UTC) From: Thomas Gleixner DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1600622689; 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=ELUNMLCQYXoHQWzGjHTiBi/GvrgBrzUdsStDgdETjPA=; b=tzqY9X8fLvmtivfsbNK0pUu8YiUj7NKf7+bQzIN33nK/SwghNMa2rz52k7m9LEaGnDxB4p 5uJRP8jzSGhdLLpPzoF07YS1dppzeAHFuaRXBxkQ6eQFewoBrpPutv3yBGdR9YKqd5UnMc Lfw64Wh81l4jTzfijbUVM/G1PeB+l9wpVjsRPd3Xz3aQUHw9+Bu78ZLn5k1aNaH9Pkc5ms Lg9Dct8esi3AxOTl0URAWW4pIL6LMaz6yDqISWtV082sZby+eUJYHhPHZSuxMGdcllbxYl qQ/7nvxbGePtOn6SDA8Bi+zAxXBj+TvBWAwr7ALWt4wsGLJLJU/NhQ4k2+3KDg== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1600622689; 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=ELUNMLCQYXoHQWzGjHTiBi/GvrgBrzUdsStDgdETjPA=; b=Ajg419VRwVNBaCnESvnWBGYX1dQ8DDFprO3wwe5+UvEno+/XgboH3A5bxhtY6hr785JAXL VPGuKWoChMzzg9BQ== To: Daniel Vetter Subject: Re: [patch RFC 00/15] mm/highmem: Provide a preemptible variant of kmap_atomic & friends In-Reply-To: <20200920082353.GG438822@phenom.ffwll.local> References: <20200919091751.011116649@linutronix.de> <87pn6hc6g1.fsf@nanos.tec.linutronix.de> <20200920082353.GG438822@phenom.ffwll.local> Date: Sun, 20 Sep 2020 19:24:49 +0200 Message-ID: <87h7rscqe6.fsf@nanos.tec.linutronix.de> MIME-Version: 1.0 X-Mailman-Approved-At: Mon, 21 Sep 2020 07:34:45 +0000 X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Juri Lelli , Peter Zijlstra , Sebastian Andrzej Siewior , dri-devel , linux-mips@vger.kernel.org, Ben Segall , Max Filippov , Guo Ren , sparclinux@vger.kernel.org, Vincent Chen , Will Deacon , Ard Biesheuvel , "open list:GENERIC INCLUDE/A..." , Vincent Guittot , Herbert Xu , Michael Ellerman , X86 ML , Russell King , linux-csky@vger.kernel.org, David Airlie , Mel Gorman , arcml , linux-xtensa@linux-xtensa.org, Paul McKenney , intel-gfx , linuxppc-dev , Steven Rostedt , Linus Torvalds , Rodrigo Vivi , Dietmar Eggemann , Linux ARM , Chris Zankel , Michal Simek , Thomas Bogendoerfer , Nick Hu , Linux-MM , Vineet Gupta , LKML , Arnd Bergmann , Paul Mackerras , Andrew Morton , Daniel Bristot de Oliveira , "David S. Miller" , Greentime Hu Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" On Sun, Sep 20 2020 at 10:23, Daniel Vetter wrote: > On Sun, Sep 20, 2020 at 08:23:26AM +0200, Thomas Gleixner wrote: >> On Sat, Sep 19 2020 at 12:37, Daniel Vetter wrote: >> > On Sat, Sep 19, 2020 at 12:35 PM Daniel Vetter wrote: >> >> I think it should be the case, but I want to double check: Will >> >> copy_*_user be allowed within a kmap_temporary section? This would >> >> allow us to ditch an absolute pile of slowpaths. >> > >> > (coffee just kicked in) copy_*_user is ofc allowed, but if you hit a >> > page fault you get a short read/write. This looks like it would remove >> > the need to handle these in a slowpath, since page faults can now be >> > served in this new kmap_temporary sections. But this sounds too good >> > to be true, so I'm wondering what I'm missing. >> >> In principle we could allow pagefaults, but not with the currently >> proposed interface which can be called from any context. Obviously if >> called from atomic context it can't handle user page faults. > > Yeah that's clear, but does the implemention need to disable pagefaults > unconditionally? As I wrote in the other reply it's not required and the final interface will neither disable preemption nor pagefaults (except for the atomic wrapper around it). Thanks, tglx _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel