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=-5.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 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 1AECBC433E0 for ; Fri, 19 Jun 2020 08:22:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E8A6120885 for ; Fri, 19 Jun 2020 08:22:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731380AbgFSIWP (ORCPT ); Fri, 19 Jun 2020 04:22:15 -0400 Received: from szxga06-in.huawei.com ([45.249.212.32]:39962 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1731369AbgFSIV1 (ORCPT ); Fri, 19 Jun 2020 04:21:27 -0400 Received: from DGGEMS401-HUB.china.huawei.com (unknown [172.30.72.60]) by Forcepoint Email with ESMTP id 2AE8129E78B79E999E1F; Fri, 19 Jun 2020 16:21:23 +0800 (CST) Received: from [127.0.0.1] (10.166.213.90) by DGGEMS401-HUB.china.huawei.com (10.3.19.201) with Microsoft SMTP Server id 14.3.487.0; Fri, 19 Jun 2020 16:21:16 +0800 Subject: Re: [PATCH v8 0/5] support reserving crashkernel above 4G on arm64 kdump To: John Donnelly , Nicolas Saenz Julienne , Bhupesh Sharma References: <20200521093805.64398-1-chenzhou10@huawei.com> <303695cc-d3ea-9f51-1489-07d27d4253d4@oracle.com> <6EA47B07-5119-49DF-9980-12A2066F22CA@oracle.com> <8463464e-5461-f328-621c-bacc6a3b88dd@huawei.com> <8E0D45DC-12BF-437D-A342-03E974D9C6D4@oracle.com> <751bbe2512628ff38002db33ce02af051d080cd2.camel@suse.de> <8ca6c3e9-b8ab-77c3-a1d3-beb513c22f1b@oracle.com> CC: Simon Horman , Devicetree List , Arnd Bergmann , Baoquan He , Linux Doc Mailing List , "Catalin Marinas" , , kexec mailing list , Linux Kernel Mailing List , Will Deacon , Rob Herring , James Morse , Prabhakar Kushwaha , Thomas Gleixner , "Prabhakar Kushwaha" , RuiRui Yang , "Ingo Molnar" , linux-arm-kernel From: chenzhou Message-ID: <03929ef5-7044-5610-c207-e497d3994f49@huawei.com> Date: Fri, 19 Jun 2020 16:21:15 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.7.1 MIME-Version: 1.0 In-Reply-To: <8ca6c3e9-b8ab-77c3-a1d3-beb513c22f1b@oracle.com> Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit X-Originating-IP: [10.166.213.90] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2020/6/19 10:32, John Donnelly wrote: > > On 6/4/20 12:01 PM, Nicolas Saenz Julienne wrote: >> On Thu, 2020-06-04 at 01:17 +0530, Bhupesh Sharma wrote: >>> Hi All, >>> >>> On Wed, Jun 3, 2020 at 9:03 PM John Donnelly >>> wrote: >>>> >>>>> On Jun 3, 2020, at 8:20 AM, chenzhou wrote: >>>>> >>>>> Hi, >>>>> >>>>> >>>>> On 2020/6/3 19:47, Prabhakar Kushwaha wrote: >>>>>> Hi Chen, >>>>>> >>>>>> On Tue, Jun 2, 2020 at 8:12 PM John Donnelly >>>>>> wrote: >>>>>>> >>>>>>>> On Jun 2, 2020, at 12:38 AM, Prabhakar Kushwaha < >>>>>>>> prabhakar.pkin@gmail.com> wrote: >>>>>>>> >>>>>>>> On Tue, Jun 2, 2020 at 3:29 AM John Donnelly < >>>>>>>> john.p.donnelly@oracle.com> wrote: >>>>>>>>> Hi . See below ! >>>>>>>>> >>>>>>>>>> On Jun 1, 2020, at 4:02 PM, Bhupesh Sharma >>>>>>>>>> wrote: >>>>>>>>>> >>>>>>>>>> Hi John, >>>>>>>>>> >>>>>>>>>> On Tue, Jun 2, 2020 at 1:01 AM John Donnelly < >>>>>>>>>> John.P.donnelly@oracle.com> wrote: >>>>>>>>>>> Hi, >>>>>>>>>>> >>>>>>>>>>> >>>>>>>>>>> On 6/1/20 7:02 AM, Prabhakar Kushwaha wrote: >>>>>>>>>>>> Hi Chen, >>>>>>>>>>>> >>>>>>>>>>>> On Thu, May 21, 2020 at 3:05 PM Chen Zhou < >>>>>>>>>>>> chenzhou10@huawei.com> wrote: >>>>>>>>>>>>> This patch series enable reserving crashkernel above 4G in >>>>>>>>>>>>> arm64. >>>>>>>>>>>>> >>>>>>>>>>>>> There are following issues in arm64 kdump: >>>>>>>>>>>>> 1. We use crashkernel=X to reserve crashkernel below 4G, >>>>>>>>>>>>> which will fail >>>>>>>>>>>>> when there is no enough low memory. >>>>>>>>>>>>> 2. Currently, crashkernel=Y@X can be used to reserve >>>>>>>>>>>>> crashkernel above 4G, >>>>>>>>>>>>> in this case, if swiotlb or DMA buffers are required, >>>>>>>>>>>>> crash dump kernel >>>>>>>>>>>>> will boot failure because there is no low memory available >>>>>>>>>>>>> for allocation. >>>>>>>>>>>>> >>>>>>>>>>>> We are getting "warn_alloc" [1] warning during boot of kdump >>>>>>>>>>>> kernel >>>>>>>>>>>> with bootargs as [2] of primary kernel. >>>>>>>>>>>> This error observed on ThunderX2 ARM64 platform. >>>>>>>>>>>> >>>>>>>>>>>> It is observed with latest upstream tag (v5.7-rc3) with this >>>>>>>>>>>> patch set >>>>>>>>>>>> and >>>>>>>>>>>> >> https://urldefense.com/v3/__https://lists.infradead.org/pipermail/kexec/2020-May/025128.html__;!!GqivPVa7Brio!LnTSARkCt0V0FozR0KmqooaH5ADtdXvs3mPdP3KRVqALmvSK2VmCkIPIhsaxbiIAAlzu$ >>>>>>>>>>>> Also **without** this patch-set >>>>>>>>>>>> " >>>>>>>>>>>> >> https://urldefense.com/v3/__https://www.spinics.net/lists/arm-kernel/msg806882.html__;!!GqivPVa7Brio!LnTSARkCt0V0FozR0KmqooaH5ADtdXvs3mPdP3KRVqALmvSK2VmCkIPIhsaxbjC6ujMA$ >>>>>>>>>>>> " >>>>>>>>>>>> >>>>>>>>>>>> This issue comes whenever crashkernel memory is reserved >>>>>>>>>>>> after 0xc000_0000. >>>>>>>>>>>> More details discussed earlier in >>>>>>>>>>>> >> https://urldefense.com/v3/__https://www.spinics.net/lists/arm-kernel/msg806882.html__;!!GqivPVa7Brio!LnTSARkCt0V0FozR0KmqooaH5ADtdXvs3mPdP3KRVqALmvSK2VmCkIPIhsaxbjC6ujMA$ >> without >>>>>>>>>>>> any >>>>>>>>>>>> solution >>>>>>>>>>>> >>>>>>>>>>>> This patch-set is expected to solve similar kind of issue. >>>>>>>>>>>> i.e. low memory is only targeted for DMA, swiotlb; So above >>>>>>>>>>>> mentioned >>>>>>>>>>>> observation should be considered/fixed. . >>>>>>>>>>>> >>>>>>>>>>>> --pk >>>>>>>>>>>> >>>>>>>>>>>> [1] >>>>>>>>>>>> [ 30.366695] DMI: Cavium Inc. Saber/Saber, BIOS >>>>>>>>>>>> TX2-FW-Release-3.1-build_01-2803-g74253a541a mm/dd/yyyy >>>>>>>>>>>> [ 30.367696] NET: Registered protocol family 16 >>>>>>>>>>>> [ 30.369973] swapper/0: page allocation failure: order:6, >>>>>>>>>>>> mode:0x1(GFP_DMA), nodemask=(null),cpuset=/,mems_allowed=0 >>>>>>>>>>>> [ 30.369980] CPU: 0 PID: 1 Comm: swapper/0 Not tainted >>>>>>>>>>>> 5.7.0-rc3+ #121 >>>>>>>>>>>> [ 30.369981] Hardware name: Cavium Inc. Saber/Saber, BIOS >>>>>>>>>>>> TX2-FW-Release-3.1-build_01-2803-g74253a541a mm/dd/yyyy >>>>>>>>>>>> [ 30.369984] Call trace: >>>>>>>>>>>> [ 30.369989] dump_backtrace+0x0/0x1f8 >>>>>>>>>>>> [ 30.369991] show_stack+0x20/0x30 >>>>>>>>>>>> [ 30.369997] dump_stack+0xc0/0x10c >>>>>>>>>>>> [ 30.370001] warn_alloc+0x10c/0x178 >>>>>>>>>>>> [ 30.370004] __alloc_pages_slowpath.constprop.111+0xb10/0 >>>>>>>>>>>> xb50 >>>>>>>>>>>> [ 30.370006] __alloc_pages_nodemask+0x2b4/0x300 >>>>>>>>>>>> [ 30.370008] alloc_page_interleave+0x24/0x98 >>>>>>>>>>>> [ 30.370011] alloc_pages_current+0xe4/0x108 >>>>>>>>>>>> [ 30.370017] dma_atomic_pool_init+0x44/0x1a4 >>>>>>>>>>>> [ 30.370020] do_one_initcall+0x54/0x228 >>>>>>>>>>>> [ 30.370027] kernel_init_freeable+0x228/0x2cc >>>>>>>>>>>> [ 30.370031] kernel_init+0x1c/0x110 >>>>>>>>>>>> [ 30.370034] ret_from_fork+0x10/0x18 >>>>>>>>>>>> [ 30.370036] Mem-Info: >>>>>>>>>>>> [ 30.370064] active_anon:0 inactive_anon:0 isolated_anon:0 >>>>>>>>>>>> [ 30.370064] active_file:0 inactive_file:0 >>>>>>>>>>>> isolated_file:0 >>>>>>>>>>>> [ 30.370064] unevictable:0 dirty:0 writeback:0 unstable:0 >>>>>>>>>>>> [ 30.370064] slab_reclaimable:34 slab_unreclaimable:4438 >>>>>>>>>>>> [ 30.370064] mapped:0 shmem:0 pagetables:14 bounce:0 >>>>>>>>>>>> [ 30.370064] free:1537719 free_pcp:219 free_cma:0 >>>>>>>>>>>> [ 30.370070] Node 0 active_anon:0kB inactive_anon:0kB >>>>>>>>>>>> active_file:0kB inactive_file:0kB unevictable:0kB >>>>>>>>>>>> isolated(anon):0kB >>>>>>>>>>>> isolated(file):0kB mapped:0kB dirty:0kB writeback:0kB >>>>>>>>>>>> shmem:0kB >>>>>>>>>>>> shmem_thp: 0kB shmem_pmdmapped: 0kB anon_thp: 0kB >>>>>>>>>>>> writeback_tmp:0kB >>>>>>>>>>>> unstable:0kB all_unreclaimable? no >>>>>>>>>>>> [ 30.370073] Node 1 active_anon:0kB inactive_anon:0kB >>>>>>>>>>>> active_file:0kB inactive_file:0kB unevictable:0kB >>>>>>>>>>>> isolated(anon):0kB >>>>>>>>>>>> isolated(file):0kB mapped:0kB dirty:0kB writeback:0kB >>>>>>>>>>>> shmem:0kB >>>>>>>>>>>> shmem_thp: 0kB shmem_pmdmapped: 0kB anon_thp: 0kB >>>>>>>>>>>> writeback_tmp:0kB >>>>>>>>>>>> unstable:0kB all_unreclaimable? no >>>>>>>>>>>> [ 30.370079] Node 0 DMA free:0kB min:0kB low:0kB high:0kB >>>>>>>>>>>> reserved_highatomic:0KB active_anon:0kB inactive_anon:0kB >>>>>>>>>>>> active_file:0kB inactive_file:0kB unevictable:0kB >>>>>>>>>>>> writepending:0kB >>>>>>>>>>>> present:128kB managed:0kB mlocked:0kB kernel_stack:0kB >>>>>>>>>>>> pagetables:0kB >>>>>>>>>>>> bounce:0kB free_pcp:0kB local_pcp:0kB free_cma:0kB >>>>>>>>>>>> [ 30.370084] lowmem_reserve[]: 0 250 6063 6063 >>>>>>>>>>>> [ 30.370090] Node 0 DMA32 free:256000kB min:408kB >>>>>>>>>>>> low:664kB >>>>>>>>>>>> high:920kB reserved_highatomic:0KB active_anon:0kB >>>>>>>>>>>> inactive_anon:0kB >>>>>>>>>>>> active_file:0kB inactive_file:0kB unevictable:0kB >>>>>>>>>>>> writepending:0kB >>>>>>>>>>>> present:269700kB managed:256000kB mlocked:0kB >>>>>>>>>>>> kernel_stack:0kB >>>>>>>>>>>> pagetables:0kB bounce:0kB free_pcp:0kB local_pcp:0kB >>>>>>>>>>>> free_cma:0kB >>>>>>>>>>>> [ 30.370094] lowmem_reserve[]: 0 0 5813 5813 >>>>>>>>>>>> [ 30.370100] Node 0 Normal free:5894876kB min:9552kB >>>>>>>>>>>> low:15504kB >>>>>>>>>>>> high:21456kB reserved_highatomic:0KB active_anon:0kB >>>>>>>>>>>> inactive_anon:0kB >>>>>>>>>>>> active_file:0kB inactive_file:0kB unevictable:0kB >>>>>>>>>>>> writepending:0kB >>>>>>>>>>>> present:8388608kB managed:5953112kB mlocked:0kB >>>>>>>>>>>> kernel_stack:21672kB >>>>>>>>>>>> pagetables:56kB bounce:0kB free_pcp:876kB local_pcp:176kB >>>>>>>>>>>> free_cma:0kB >>>>>>>>>>>> [ 30.370104] lowmem_reserve[]: 0 0 0 0 >>>>>>>>>>>> [ 30.370107] Node 0 DMA: 0*4kB 0*8kB 0*16kB 0*32kB 0*64kB >>>>>>>>>>>> 0*128kB >>>>>>>>>>>> 0*256kB 0*512kB 0*1024kB 0*2048kB 0*4096kB = 0kB >>>>>>>>>>>> [ 30.370113] Node 0 DMA32: 0*4kB 0*8kB 0*16kB 0*32kB >>>>>>>>>>>> 0*64kB 0*128kB >>>>>>>>>>>> 0*256kB 0*512kB 0*1024kB 1*2048kB (M) 62*4096kB (M) = >>>>>>>>>>>> 256000kB >>>>>>>>>>>> [ 30.370119] Node 0 Normal: 2*4kB (M) 3*8kB (ME) 2*16kB >>>>>>>>>>>> (UE) 3*32kB >>>>>>>>>>>> (UM) 1*64kB (U) 2*128kB (M) 2*256kB (ME) 3*512kB (ME) >>>>>>>>>>>> 3*1024kB (ME) >>>>>>>>>>>> 3*2048kB (UME) 1436*4096kB (M) = 5893600kB >>>>>>>>>>>> [ 30.370129] Node 0 hugepages_total=0 hugepages_free=0 >>>>>>>>>>>> hugepages_surp=0 hugepages_size=1048576kB >>>>>>>>>>>> [ 30.370130] 0 total pagecache pages >>>>>>>>>>>> [ 30.370132] 0 pages in swap cache >>>>>>>>>>>> [ 30.370134] Swap cache stats: add 0, delete 0, find 0/0 >>>>>>>>>>>> [ 30.370135] Free swap = 0kB >>>>>>>>>>>> [ 30.370136] Total swap = 0kB >>>>>>>>>>>> [ 30.370137] 2164609 pages RAM >>>>>>>>>>>> [ 30.370139] 0 pages HighMem/MovableOnly >>>>>>>>>>>> [ 30.370140] 612331 pages reserved >>>>>>>>>>>> [ 30.370141] 0 pages hwpoisoned >>>>>>>>>>>> [ 30.370143] DMA: failed to allocate 256 KiB pool for >>>>>>>>>>>> atomic >>>>>>>>>>>> coherent allocation >>>>>>>>>>> During my testing I saw the same error and Chen's solution >>>>>>>>>>> corrected it . >>>>>>>>>> Which combination you are using on your side? I am using >>>>>>>>>> Prabhakar's >>>>>>>>>> suggested environment and can reproduce the issue >>>>>>>>>> with or without Chen's crashkernel support above 4G patchset. >>>>>>>>>> >>>>>>>>>> I am also using a ThunderX2 platform with latest makedumpfile >>>>>>>>>> code and >>>>>>>>>> kexec-tools (with the suggested patch >>>>>>>>>> < >>>>>>>>>> >> https://urldefense.com/v3/__https://lists.infradead.org/pipermail/kexec/2020-May/025128.html__;!!GqivPVa7Brio!J6lUig58-Gw6TKZnEEYzEeSU36T-1SqlB1kImU00xtX_lss5Tx-JbUmLE9TJC3foXBLg$ >>>>>>>>>>> ). >>>>>>>>>> Thanks, >>>>>>>>>> Bhupesh >>>>>>>>> I did this activity 5 months ago and I have moved on to other >>>>>>>>> activities. My DMA failures were related to PCI devices that could >>>>>>>>> not be enumerated because low-DMA space was not available when >>>>>>>>> crashkernel was moved above 4G; I don’t recall the exact platform. >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> For this failure , >>>>>>>>> >>>>>>>>>>>> DMA: failed to allocate 256 KiB pool for atomic >>>>>>>>>>>> coherent allocation >>>>>>>>> Is due to : >>>>>>>>> >>>>>>>>> >>>>>>>>> 3618082c >>>>>>>>> ("arm64 use both ZONE_DMA and ZONE_DMA32") >>>>>>>>> >>>>>>>>> With the introduction of ZONE_DMA to support the Raspberry DMA >>>>>>>>> region below 1G, the crashkernel is placed in the upper 4G >>>>>>>>> ZONE_DMA_32 region. Since the crashkernel does not have access >>>>>>>>> to the ZONE_DMA region, it prints out call trace during bootup. >>>>>>>>> >>>>>>>>> It is due to having this CONFIG item ON : >>>>>>>>> >>>>>>>>> >>>>>>>>> CONFIG_ZONE_DMA=y >>>>>>>>> >>>>>>>>> Turning off ZONE_DMA fixes a issue and Raspberry PI 4 will >>>>>>>>> use the device tree to specify memory below 1G. >>>>>>>>> >>>>>>>>> >>>>>>>> Disabling ZONE_DMA is temporary solution. We may need proper >>>>>>>> solution >>>>>>> Perhaps the Raspberry platform configuration dependencies need >>>>>>> separated from “server class” Arm equipment ? Or auto-configured on >>>>>>> boot ? Consult an expert ;-) >>>>>>> >>>>>>> >>>>>>> >>>>>>>>> I would like to see Chen’s feature added , perhaps as >>>>>>>>> EXPERIMENTAL, so we can get some configuration testing done on >>>>>>>>> it. It corrects having a DMA zone in low memory while crash- >>>>>>>>> kernel is above 4GB. This has been going on for a year now. >>>>>>>> I will also like this patch to be added in Linux as early as >>>>>>>> possible. >>>>>>>> >>>>>>>> Issue mentioned by me happens with or without this patch. >>>>>>>> >>>>>>>> This patch-set can consider fixing because it uses low memory for >>>>>>>> DMA >>>>>>>> & swiotlb only. >>>>>>>> We can consider restricting crashkernel within the required range >>>>>>>> like below >>>>>>>> >>>>>>>> diff --git a/kernel/crash_core.c b/kernel/crash_core.c >>>>>>>> index 7f9e5a6dc48c..bd67b90d35bd 100644 >>>>>>>> --- a/kernel/crash_core.c >>>>>>>> +++ b/kernel/crash_core.c >>>>>>>> @@ -354,7 +354,7 @@ int __init reserve_crashkernel_low(void) >>>>>>>> return 0; >>>>>>>> } >>>>>>>> >>>>>>>> - low_base = memblock_find_in_range(0, 1ULL << 32, low_size, >>>>>>>> CRASH_ALIGN); >>>>>>>> + low_base = memblock_find_in_range(0,0xc0000000, low_size, >>>>>>>> CRASH_ALIGN); >>>>>>>> if (!low_base) { >>>>>>>> pr_err("Cannot reserve %ldMB crashkernel low memory, >>>>>>>> please try smaller size.\n", >>>>>>>> (unsigned long)(low_size >> 20)); >>>>>>>> >>>>>>>> >>>>>>> I suspect 0xc0000000 would need to be a CONFIG item and not >>>>>>> hard-coded. >>>>>>> >>>>>> if you consider this as valid change, can you please incorporate as >>>>>> part of your patch-set. >>>>> After commit 1a8e1cef7 ("arm64: use both ZONE_DMA and ZONE_DMA32")，the 0- >>>>> 4G memory is splited >>>>> to DMA [mem 0x0000000000000000-0x000000003fffffff] and DMA32 [mem >>>>> 0x0000000040000000-0x00000000ffffffff] on arm64. >>>>> >>>>> From the above discussion, on your platform, the low crashkernel fall in >>>>> DMA32 region, but your environment needs to access DMA >>>>> region, so there is the call trace. >>>>> >>>>> I have a question, why do you choose 0xc0000000 here? >>>>> >>>>> Besides, this is common code, we also need to consider about x86. >>>>> >>>> + nsaenzjulienne@suse.de >> Thanks for adding me to the conversation, and sorry for the headaches. >> >>>> Exactly . This is why it needs to be a CONFIG option for Raspberry >>>> .., or device tree option. >>>> >>>> >>>> We could revert 1a8e1cef7 since it broke Arm kdump too. >>> Well, unfortunately the patch for commit 1a8e1cef7603 ("arm64: use >>> both ZONE_DMA and ZONE_DMA32") was not Cc'ed to the kexec mailing >>> list, thus we couldn't get many eyes on it for a thorough review from >>> kexec/kdump p-o-v. >>> >>> Also we historically never had distinction in common arch code on the >>> basis of the intended end use-case: embedded, server or automotive, so >>> I am not sure introducing a Raspberry specific CONFIG option would be >>> a good idea. >> +1 >> >> From the distros perspective it's very important to keep a single kernel image. >> >>> So, rather than reverting the patch, we can look at addressing the >>> same properly this time - especially from a kdump p-o-v. >>> This issue has been reported by some Red Hat arm64 partners with >>> upstream kernel also and as we have noticed in the past as well, >>> hardcoding the placement of the crashkernel base address (unless the >>> base address is specified by a crashkernel=X@Y like bootargs) is also >>> not a portable suggestion. >>> >>> I am working on a possible fix and will have more updates on the same >>> in a day-or-two. >> Please keep me in the loop, we've also had issues pointing to this reported by >> SUSE partners. I can do some testing both on the RPi4 and on big servers that >> need huge crashkernel sizes. >> >> Regards, >> Nicolas >> > > Hi > > Has there been any progress on this ? It appears we are stalled because Nicolas's and Chen's changes are not compatible . One is needed for RPi4 and the other for server class equipment. > > > Thanks, > > John > > Hi all, Thanks for John's reminder. commit 1a8e1cef7 ("arm64: use both ZONE_DMA and ZONE_DMA32") broken the arm64 kdump, there is a simple solution similar to pk's to fix this, see below: In crash dump kernel, if the peripherals need to use ZONE_DMA like the the Raspberry Pi 4, based on my solution, we adjusted the memory range in memblock_find_in_range. diff --git a/kernel/crash_core.c b/kernel/crash_core.c index a7580d291c37..eb16c6d54b73 100644 --- a/kernel/crash_core.c +++ b/kernel/crash_core.c @@ -320,6 +320,7 @@ int __init reserve_crashkernel_low(void) unsigned long long base, low_base = 0, low_size = 0; unsigned long total_low_mem; int ret; + phys_addr_t crash_max = 1ULL << 32; total_low_mem = memblock_mem_size(1UL << (32 - PAGE_SHIFT)); @@ -352,7 +353,12 @@ int __init reserve_crashkernel_low(void) return 0; } - low_base = memblock_find_in_range(0, 1ULL << 32, low_size, CRASH_ALIGN); +#ifdef CONFIG_ARM64 + if (IS_ENABLED(CONFIG_ZONE_DMA)) { + crash_max = arm64_dma_phys_limit; + } +#endif + low_base = memblock_find_in_range(0, crash_max, low_size, CRASH_ALIGN); if (!low_base) { pr_err("Cannot reserve %ldMB crashkernel low memory, please try smaller size.\n", (unsigned long)(low_size >> 20)); Thanks, Chen Zhou > > . >