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=-8.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 9471FC433E0 for ; Thu, 2 Jul 2020 07:50:10 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 5266020874 for ; Thu, 2 Jul 2020 07:50:10 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="1tzmwO6b" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5266020874 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id BB9BC8D0013; Thu, 2 Jul 2020 03:50:09 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id B69648D0001; Thu, 2 Jul 2020 03:50:09 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id A58258D0013; Thu, 2 Jul 2020 03:50:09 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0181.hostedemail.com [216.40.44.181]) by kanga.kvack.org (Postfix) with ESMTP id 910038D0001 for ; Thu, 2 Jul 2020 03:50:09 -0400 (EDT) Received: from smtpin04.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id 0C548180AD806 for ; Thu, 2 Jul 2020 07:50:09 +0000 (UTC) X-FDA: 76992362538.04.cent82_3f180db26e87 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin04.hostedemail.com (Postfix) with ESMTP id DE514800A335 for ; Thu, 2 Jul 2020 07:50:08 +0000 (UTC) X-HE-Tag: cent82_3f180db26e87 X-Filterd-Recvd-Size: 5527 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf49.hostedemail.com (Postfix) with ESMTP for ; Thu, 2 Jul 2020 07:50:08 +0000 (UTC) Received: from willie-the-truck (236.31.169.217.in-addr.arpa [217.169.31.236]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 5F9EB20936; Thu, 2 Jul 2020 07:50:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1593676207; bh=OPwzfImFs/6d/wxmTj/SDF/k3f/jGxD4d+RjrzyjUhY=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=1tzmwO6bBgv8e1nwdoCor7eoYs88C56cCi+b1LCWxsslV3Obsc9H5N3DTD0s4kOVb nkn4R3y7DQPj5Agqp5PfpNJs4ca/7dhafI+z0F6Kcb9Mkvdl0vYkOTgV86DU6NajuG s2sQPFWem5d6mVKrB7CLIcoWue9AxNGe9AlfXe3E= Date: Thu, 2 Jul 2020 08:50:02 +0100 From: Will Deacon To: Bhupesh Sharma Cc: cgroups@vger.kernel.org, linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org, bhupesh.linux@gmail.com, Johannes Weiner , Michal Hocko , Vladimir Davydov , James Morse , Mark Rutland , Catalin Marinas , linux-kernel@vger.kernel.org, kexec@lists.infradead.org Subject: Re: [PATCH 2/2] arm64: Allocate crashkernel always in ZONE_DMA Message-ID: <20200702075001.GA16113@willie-the-truck> References: <1593641660-13254-1-git-send-email-bhsharma@redhat.com> <1593641660-13254-3-git-send-email-bhsharma@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1593641660-13254-3-git-send-email-bhsharma@redhat.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-Rspamd-Queue-Id: DE514800A335 X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam05 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Thu, Jul 02, 2020 at 03:44:20AM +0530, Bhupesh Sharma wrote: > commit bff3b04460a8 ("arm64: mm: reserve CMA and crashkernel in > ZONE_DMA32") allocates crashkernel for arm64 in the ZONE_DMA32. > > However as reported by Prabhakar, this breaks kdump kernel booting in > ThunderX2 like arm64 systems. I have noticed this on another ampere > arm64 machine. The OOM log in the kdump kernel looks like this: > > [ 0.240552] DMA: preallocated 128 KiB GFP_KERNEL pool for atomic allocations > [ 0.247713] swapper/0: page allocation failure: order:1, mode:0xcc1(GFP_KERNEL|GFP_DMA), nodemask=(null),cpuset=/,mems_allowed=0 > <..snip..> > [ 0.274706] Call trace: > [ 0.277170] dump_backtrace+0x0/0x208 > [ 0.280863] show_stack+0x1c/0x28 > [ 0.284207] dump_stack+0xc4/0x10c > [ 0.287638] warn_alloc+0x104/0x170 > [ 0.291156] __alloc_pages_slowpath.constprop.106+0xb08/0xb48 > [ 0.296958] __alloc_pages_nodemask+0x2ac/0x2f8 > [ 0.301530] alloc_page_interleave+0x20/0x90 > [ 0.305839] alloc_pages_current+0xdc/0xf8 > [ 0.309972] atomic_pool_expand+0x60/0x210 > [ 0.314108] __dma_atomic_pool_init+0x50/0xa4 > [ 0.318504] dma_atomic_pool_init+0xac/0x158 > [ 0.322813] do_one_initcall+0x50/0x218 > [ 0.326684] kernel_init_freeable+0x22c/0x2d0 > [ 0.331083] kernel_init+0x18/0x110 > [ 0.334600] ret_from_fork+0x10/0x18 > > This patch limits the crashkernel allocation to the first 1GB of > the RAM accessible (ZONE_DMA), as otherwise we might run into OOM > issues when crashkernel is executed, as it might have been originally > allocated from either a ZONE_DMA32 memory or mixture of memory chunks > belonging to both ZONE_DMA and ZONE_DMA32. How does this interact with this ongoing series: https://lore.kernel.org/r/20200628083458.40066-1-chenzhou10@huawei.com (patch 4, in particular) > Fixes: bff3b04460a8 ("arm64: mm: reserve CMA and crashkernel in ZONE_DMA32") > Cc: Johannes Weiner > Cc: Michal Hocko > Cc: Vladimir Davydov > Cc: James Morse > Cc: Mark Rutland > Cc: Will Deacon > Cc: Catalin Marinas > Cc: cgroups@vger.kernel.org > Cc: linux-mm@kvack.org > Cc: linux-arm-kernel@lists.infradead.org > Cc: linux-kernel@vger.kernel.org > Cc: kexec@lists.infradead.org > Reported-by: Prabhakar Kushwaha > Signed-off-by: Bhupesh Sharma > --- > arch/arm64/mm/init.c | 16 ++++++++++++++-- > 1 file changed, 14 insertions(+), 2 deletions(-) > > diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c > index 1e93cfc7c47a..02ae4d623802 100644 > --- a/arch/arm64/mm/init.c > +++ b/arch/arm64/mm/init.c > @@ -91,8 +91,15 @@ static void __init reserve_crashkernel(void) > crash_size = PAGE_ALIGN(crash_size); > > if (crash_base == 0) { > - /* Current arm64 boot protocol requires 2MB alignment */ > - crash_base = memblock_find_in_range(0, arm64_dma32_phys_limit, > + /* Current arm64 boot protocol requires 2MB alignment. > + * Also limit the crashkernel allocation to the first > + * 1GB of the RAM accessible (ZONE_DMA), as otherwise we > + * might run into OOM issues when crashkernel is executed, > + * as it might have been originally allocated from > + * either a ZONE_DMA32 memory or mixture of memory > + * chunks belonging to both ZONE_DMA and ZONE_DMA32. > + */ This comment needs help. Why does putting the crashkernel in ZONE_DMA prevent "OOM issues"? Will