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=-6.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=ham 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 F2553C43603 for ; Mon, 9 Dec 2019 05:43:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C5AD8206D3 for ; Mon, 9 Dec 2019 05:43:24 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=ellerman.id.au header.i=@ellerman.id.au header.b="igRorkS9" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726960AbfLIFnX (ORCPT ); Mon, 9 Dec 2019 00:43:23 -0500 Received: from ozlabs.org ([203.11.71.1]:37465 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726408AbfLIFnX (ORCPT ); Mon, 9 Dec 2019 00:43:23 -0500 Received: from authenticated.ozlabs.org (localhost [127.0.0.1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange ECDHE (P-256) server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by mail.ozlabs.org (Postfix) with ESMTPSA id 47WXD73mCSz9sP6; Mon, 9 Dec 2019 16:43:19 +1100 (AEDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ellerman.id.au; s=201909; t=1575870201; bh=EU4lPc5IWHfktnisegd6j5Y6xKovFoBVkVjlsMX4/pE=; h=From:To:Cc:Subject:In-Reply-To:References:Date:From; b=igRorkS97HOON5GNqt21oBCytjvq3MO/I/pbqKeA+/w/EC95/C9ComNHV83pfOIJo b4BGFIKg3r1DHuXk2sPf8s03P3Ccx8hYkery5YB1CDqnFS8wlBMbZBLR3vtejfl7jy h6x4j9eJEGkJyxOc4uI8gM+N1rH/AVk/tDaClHwM+fcgo3GK4PTf+I/L3YSt4sLzOe RiNCkQNfxvAXHlPpCsDKltYrZ92IGr8D/O4Hj8MjwAiYJrgDx589PIR6zviioFUxG3 +7ISbse34yFB4L6wshgcHwRY2JHcyhf5nNMe6B1HMP9BmG6lP0V29ZZes4qk3i1bZa 6BWY4Z7Sl5Y9Q== From: Michael Ellerman To: Mike Rapoport , linux-kernel@vger.kernel.org Cc: linuxppc-dev@lists.ozlabs.org, linux-arch@vger.kernel.org, linux-mm@kvack.org, iommu@lists.linux-foundation.org, Mike Rapoport , Christian Zigotzky , Benjamin Herrenschmidt , Christoph Hellwig , Darren Stevens , mad skateman , Nicolas Saenz Julienne , Paul Mackerras , Robin Murphy , Rob Herring Subject: Re: [PATCH] powerpc: ensure that swiotlb buffer is allocated from low memory In-Reply-To: <20191204123524.22919-1-rppt@kernel.org> References: <20191204123524.22919-1-rppt@kernel.org> Date: Mon, 09 Dec 2019 16:43:17 +1100 Message-ID: <87h82aqcju.fsf@mpe.ellerman.id.au> MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Mike Rapoport writes: > From: Mike Rapoport > > Some powerpc platforms (e.g. 85xx) limit DMA-able memory way below 4G. If a > system has more physical memory than this limit, the swiotlb buffer is not > addressable because it is allocated from memblock using top-down mode. > > Force memblock to bottom-up mode before calling swiotlb_init() to ensure > that the swiotlb buffer is DMA-able. > > Link: https://lkml.kernel.org/r/F1EBB706-73DF-430E-9020-C214EC8ED5DA@xenosoft.de This wasn't bisected, but I thought it was a regression. Do we know what commit caused it? Was it 25078dc1f74b ("powerpc: use mm zones more sensibly") ? Or was that a red herring? cheers > Reported-by: Christian Zigotzky > Signed-off-by: Mike Rapoport > Cc: Benjamin Herrenschmidt > Cc: Christoph Hellwig > Cc: Darren Stevens > Cc: mad skateman > Cc: Michael Ellerman > Cc: Nicolas Saenz Julienne > Cc: Paul Mackerras > Cc: Robin Murphy > Cc: Rob Herring > --- > arch/powerpc/mm/mem.c | 8 ++++++++ > 1 file changed, 8 insertions(+) > > diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c > index be941d382c8d..14c2c53e3f9e 100644 > --- a/arch/powerpc/mm/mem.c > +++ b/arch/powerpc/mm/mem.c > @@ -260,6 +260,14 @@ void __init mem_init(void) > BUILD_BUG_ON(MMU_PAGE_COUNT > 16); > > #ifdef CONFIG_SWIOTLB > + /* > + * Some platforms (e.g. 85xx) limit DMA-able memory way below > + * 4G. We force memblock to bottom-up mode to ensure that the > + * memory allocated in swiotlb_init() is DMA-able. > + * As it's the last memblock allocation, no need to reset it > + * back to to-down. > + */ > + memblock_set_bottom_up(true); > swiotlb_init(0); > #endif > > -- > 2.24.0