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=-8.1 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_2 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 502E2C54FC9 for ; Tue, 21 Apr 2020 09:35:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3083E206E9 for ; Tue, 21 Apr 2020 09:35:38 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=flygoat.com header.i=@flygoat.com header.b="pN+fuGxU" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728548AbgDUJfh (ORCPT ); Tue, 21 Apr 2020 05:35:37 -0400 Received: from vultr.net.flygoat.com ([149.28.68.211]:59174 "EHLO vultr.net.flygoat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725920AbgDUJfg (ORCPT ); Tue, 21 Apr 2020 05:35:36 -0400 Received: from flygoat-x1e (unknown [IPv6:240e:390:49b:be80::d68]) by vultr.net.flygoat.com (Postfix) with ESMTPSA id 39CFA20CD4; Tue, 21 Apr 2020 09:35:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=flygoat.com; s=vultr; t=1587461736; bh=SunN0yp4ZrEQa6v2RmilOpKDVg1C0zEfHQyzzIU14rk=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=pN+fuGxUC6T5VsMYLJDJBMXAE4pcc4TP0CjBJ2bn2Ki88GX52hnp/UJcNAS3wXiRo 9jfN6v/y2ZuJHxiI3PZPsbQn8oULibbLyt6xVKOCszDOw+YAdW1QiR6iXuf+Xl7DPv zmdkafKG0vrf58lQHRl3XPJeAXiLZUDk8VO6xu1aPEzsQ/po2wpgje87bt3ET5HttT rBDtMVMjstGSXRoUzNvMy20py6vSu+HM3AvzO8rcGslbaLs7qigKYXrxF84NKch8Tz 5mGTf5YYmLJuKfq7wQX4UCuxS5SR9KggwjK8x0suNC7U4hIYNrfDFphTydFfrM3syF /Im6eyY9Tq+Kg== Date: Tue, 21 Apr 2020 17:35:25 +0800 From: Jiaxun Yang To: Tiezhu Yang Cc: Thomas Bogendoerfer , linux-mips@vger.kernel.org, linux-kernel@vger.kernel.org, Xuefeng Li , Juxin Gao Subject: Re: [PATCH 3/3] MIPS: Reduce possibility of kernel panic under CONFIG_SWIOTLB Message-ID: <20200421173525.460949b0@flygoat-x1e> In-Reply-To: <1587459869-12183-4-git-send-email-yangtiezhu@loongson.cn> References: <1587459869-12183-1-git-send-email-yangtiezhu@loongson.cn> <1587459869-12183-4-git-send-email-yangtiezhu@loongson.cn> X-Mailer: Claws Mail 3.17.5 (GTK+ 2.24.32; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 21 Apr 2020 17:04:29 +0800 Tiezhu Yang wrote: > In the current code, if CONFIG_SWIOTLB is set, when failed to get IO > TLB memory from the low pages by plat_swiotlb_setup(), it may lead to > the boot process failed with kernel panic. Hi Tiezhu, Thanks for you patch. Firstly, your commit message should be more straight forward. Please describe what you have changed (e.g. MIPS: Set memblock bottom up) instead of what you solved. > > (1) On the Loongson and SiByte platform > arch/mips/loongson64/dma.c > arch/mips/sibyte/common/dma.c > void __init plat_swiotlb_setup(void) > { > swiotlb_init(1); > } > > kernel/dma/swiotlb.c > void __init > swiotlb_init(int verbose) > { > ... > vstart = memblock_alloc_low(PAGE_ALIGN(bytes), PAGE_SIZE); > if (vstart && !swiotlb_init_with_tbl(vstart, io_tlb_nslabs, > verbose)) return; > ... > pr_warn("Cannot allocate buffer"); > no_iotlb_memory = true; > } > > phys_addr_t swiotlb_tbl_map_single() > { > ... > if (no_iotlb_memory) > panic("Can not allocate SWIOTLB buffer earlier ..."); > ... > } > > (2) On the Cavium OCTEON platform > arch/mips/cavium-octeon/dma-octeon.c > void __init plat_swiotlb_setup(void) > { > ... > octeon_swiotlb = memblock_alloc_low(swiotlbsize, PAGE_SIZE); > if (!octeon_swiotlb) > panic("%s: Failed to allocate %zu bytes align=%lx\n", > __func__, swiotlbsize, PAGE_SIZE); > ... > } > > Because IO_TLB_DEFAULT_SIZE is 64M, if the rest size of low memory is > less than 64M when call plat_swiotlb_setup(), we can easily reproduce > the panic case. > > In order to reduce the possibility of kernel panic when failed to get > IO TLB memory under CONFIG_SWIOTLB, it is better to allocate low > memory as small as possible before plat_swiotlb_setup(), so make > sparse_init() using top-down allocation. AFAIK there are some reasons that we set it to bottom_up. On some platforms, bootloader won't place cmdline & devicetree into reserved memory but place them just after kernel in memory. That means if you set it as bottom up, then early allocate memory might collide with these boot arguments. I'm not even sure if it works fine on Loongson with early PMON. I had met that issue before, the solution for me is to reduce SWIOTLB size. > > Reported-by: Juxin Gao > Co-developed-by: Juxin Gao > Signed-off-by: Juxin Gao > Signed-off-by: Tiezhu Yang > --- > arch/mips/kernel/setup.c | 10 ++++++++++ > 1 file changed, 10 insertions(+) > > diff --git a/arch/mips/kernel/setup.c b/arch/mips/kernel/setup.c > index 5481a0c..8db533c 100644 > --- a/arch/mips/kernel/setup.c > +++ b/arch/mips/kernel/setup.c > @@ -700,7 +700,17 @@ static void __init arch_mem_init(char > **cmdline_p) memblock_reserve(crashk_res.start, > resource_size(&crashk_res)); #endif > device_tree_init(); > + > + /* > + * In order to reduce the possibility of kernel panic when > failed to > + * get IO TLB memory under CONFIG_SWIOTLB, it is better to > allocate > + * low memory as small as possible before > plat_swiotlb_setup(), so > + * make sparse_init() using top-down allocation. > + */ > + memblock_set_bottom_up(false); > sparse_init(); > + memblock_set_bottom_up(true); > + > plat_swiotlb_setup(); > > dma_contiguous_reserve(PFN_PHYS(max_low_pfn)); -- Jiaxun Yang