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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 34524C433FE for ; Mon, 21 Nov 2022 12:00:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231421AbiKUMAV (ORCPT ); Mon, 21 Nov 2022 07:00:21 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58270 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231325AbiKUMAP (ORCPT ); Mon, 21 Nov 2022 07:00:15 -0500 Received: from szxga01-in.huawei.com (szxga01-in.huawei.com [45.249.212.187]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 59C1951309; Mon, 21 Nov 2022 04:00:14 -0800 (PST) Received: from dggpemm500024.china.huawei.com (unknown [172.30.72.56]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4NG5Xv5FzGzmW5v; Mon, 21 Nov 2022 19:59:43 +0800 (CST) Received: from dggpemm500006.china.huawei.com (7.185.36.236) by dggpemm500024.china.huawei.com (7.185.36.203) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.31; Mon, 21 Nov 2022 20:00:12 +0800 Received: from [10.174.178.55] (10.174.178.55) by dggpemm500006.china.huawei.com (7.185.36.236) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.31; Mon, 21 Nov 2022 20:00:11 +0800 Subject: Re: [PATCH v4 2/2] arm64: kdump: Support crashkernel=X fall back to reserve region above DMA zones To: Baoquan He CC: Dave Young , Vivek Goyal , , , Catalin Marinas , Will Deacon , , Jonathan Corbet , , "Eric W . Biederman" , Randy Dunlap , Feng Zhou , Kefeng Wang , Chen Zhou , John Donnelly , "Dave Kleikamp" References: <20221116121044.1690-1-thunder.leizhen@huawei.com> <20221116121044.1690-3-thunder.leizhen@huawei.com> From: "Leizhen (ThunderTown)" Message-ID: <0c3358aa-251f-cd47-e6d6-6408abacdea5@huawei.com> Date: Mon, 21 Nov 2022 20:00:11 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.7.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.174.178.55] X-ClientProxiedBy: dggems705-chm.china.huawei.com (10.3.19.182) To dggpemm500006.china.huawei.com (7.185.36.236) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2022/11/21 16:31, Baoquan He wrote: > On 11/16/22 at 08:10pm, Zhen Lei wrote: >> For crashkernel=X without '@offset', select a region within DMA zones >> first, and fall back to reserve region above DMA zones. This allows >> users to use the same configuration on multiple platforms. >> >> Signed-off-by: Zhen Lei >> Acked-by: Baoquan He >> --- >> Documentation/admin-guide/kernel-parameters.txt | 2 +- >> arch/arm64/mm/init.c | 17 ++++++++++++++++- >> 2 files changed, 17 insertions(+), 2 deletions(-) >> >> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt >> index a7b7147447b8bf8..ef6d922ed26b9dc 100644 >> --- a/Documentation/admin-guide/kernel-parameters.txt >> +++ b/Documentation/admin-guide/kernel-parameters.txt >> @@ -842,7 +842,7 @@ >> memory region [offset, offset + size] for that kernel >> image. If '@offset' is omitted, then a suitable offset >> is selected automatically. >> - [KNL, X86-64] Select a region under 4G first, and >> + [KNL, X86-64, ARM64] Select a region under 4G first, and >> fall back to reserve region above 4G when '@offset' >> hasn't been specified. >> See Documentation/admin-guide/kdump/kdump.rst for further details. >> diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c >> index ba7227179822d10..58a0bb2c17f18cf 100644 >> --- a/arch/arm64/mm/init.c >> +++ b/arch/arm64/mm/init.c >> @@ -132,6 +132,7 @@ static void __init reserve_crashkernel(void) >> unsigned long long crash_max = CRASH_ADDR_LOW_MAX; >> char *cmdline = boot_command_line; >> int ret; >> + bool fixed_base = false; >> >> if (!IS_ENABLED(CONFIG_KEXEC_CORE)) >> return; >> @@ -163,12 +164,26 @@ static void __init reserve_crashkernel(void) >> crash_size = PAGE_ALIGN(crash_size); >> >> /* User specifies base address explicitly. */ >> - if (crash_base) >> + if (crash_base) { >> + fixed_base = true; >> crash_max = crash_base + crash_size; >> + } >> >> +retry: >> crash_base = memblock_phys_alloc_range(crash_size, CRASH_ALIGN, >> crash_base, crash_max); > > This pachset looks good to me. While we observed a unexpected case, > where a reserved region cross the high and low meomry region. I noticed > Catalin has pointed that out. Even with the suggested code, we could > have the kernel parameters like: crashkernel=512M,high > crashkernel=128M,low, we finally have [4G-126M, 4G+386M], [1G, 1G+128M] > regions in running kernel. This looks strange. Is high-end memory fragmented? Add boot option memblock=debug and watch? > > I am wondering if we can specify explicit search_base in > memblock_phys_alloc_range() to avoid above case. Like this, > crashkernel,high region will only exist in high memory, crashkernel,low > region only exists in low memory region. I made a draft patch based on > this patchset to present what the code looks like. Looks good to me. > > diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c > index 58a0bb2c17f1..fd9d35e17a62 100644 > --- a/arch/arm64/mm/init.c > +++ b/arch/arm64/mm/init.c > @@ -127,7 +127,7 @@ static int __init reserve_crashkernel_low(unsigned long long low_size) > */ > static void __init reserve_crashkernel(void) > { > - unsigned long long crash_base, crash_size; > + unsigned long long crash_base, crash_size, search_base; search_base needs to be initialized to 0. > unsigned long long crash_low_size = 0; > unsigned long long crash_max = CRASH_ADDR_LOW_MAX; > char *cmdline = boot_command_line; > @@ -155,6 +155,7 @@ static void __init reserve_crashkernel(void) > else if (ret) > return; > > + search_base = CRASH_ADDR_LOW_MAX; > crash_max = CRASH_ADDR_HIGH_MAX; > } else if (ret || !crash_size) { > /* The specified value is invalid */ > @@ -166,12 +167,13 @@ static void __init reserve_crashkernel(void) > /* User specifies base address explicitly. */ > if (crash_base) { > fixed_base = true; > + search_base = crash_base; > crash_max = crash_base + crash_size; > } > > retry: > crash_base = memblock_phys_alloc_range(crash_size, CRASH_ALIGN, > - crash_base, crash_max); > + search_base, crash_max); > if (!crash_base) { > /* > * If the first attempt was for low memory, fall back to > @@ -180,6 +182,7 @@ static void __init reserve_crashkernel(void) > */ > if (!fixed_base && (crash_max == CRASH_ADDR_LOW_MAX)) { > crash_max = CRASH_ADDR_HIGH_MAX; > + search_base = CRASH_ADDR_LOW_MAX; > crash_low_size = DEFAULT_CRASH_KERNEL_LOW_SIZE; > goto retry; > } > @@ -189,7 +192,7 @@ static void __init reserve_crashkernel(void) > return; > } > > - if ((crash_base > CRASH_ADDR_LOW_MAX - crash_low_size) && > + if ((crash_base > CRASH_ADDR_LOW_MAX) && > crash_low_size && reserve_crashkernel_low(crash_low_size)) { > memblock_phys_free(crash_base, crash_size); > return; > > . > -- Regards, Zhen Lei