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=-10.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING, NICE_REPLY_A,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 7F93FC43461 for ; Tue, 15 Sep 2020 07:17:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3367E2080C for ; Tue, 15 Sep 2020 07:17:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726091AbgIOHRI (ORCPT ); Tue, 15 Sep 2020 03:17:08 -0400 Received: from szxga05-in.huawei.com ([45.249.212.191]:12260 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726062AbgIOHRF (ORCPT ); Tue, 15 Sep 2020 03:17:05 -0400 Received: from DGGEMS405-HUB.china.huawei.com (unknown [172.30.72.58]) by Forcepoint Email with ESMTP id 7EDE4213A5CEF33B6F5B; Tue, 15 Sep 2020 15:17:00 +0800 (CST) Received: from [10.174.176.220] (10.174.176.220) by DGGEMS405-HUB.china.huawei.com (10.3.19.205) with Microsoft SMTP Server id 14.3.487.0; Tue, 15 Sep 2020 15:16:53 +0800 Subject: Re: [PATCH v12 0/9] support reserving crashkernel above 4G on arm64 kdump To: , References: <20200907134745.25732-1-chenzhou10@huawei.com> CC: , , , , , , , , , , , , , , , , , , , , From: chenzhou Message-ID: <05b1fdbb-5bb3-1345-14ac-9bf91df16aa4@huawei.com> Date: Tue, 15 Sep 2020 15:16:51 +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: <20200907134745.25732-1-chenzhou10@huawei.com> Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.174.176.220] X-CFilter-Loop: Reflected Sender: linux-doc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org On 2020/9/7 21:47, Chen Zhou wrote: > 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. If reserving crashkernel above 4G, in this case, crash dump > kernel will boot failure because there is no low memory available > for allocation. > 3. Since commit 1a8e1cef7603 ("arm64: use both ZONE_DMA and ZONE_DMA32"), > if the memory reserved for crash dump kernel falled in ZONE_DMA32, > the devices in crash dump kernel need to use ZONE_DMA will alloc > fail. > > To solve these issues, change the behavior of crashkernel=X. > crashkernel=X tries low allocation in DMA zone, and fall back to > high allocation if it fails. > If requized size X is too large and leads to very little low memory > in DMA zone after low allocation, the system may not work normally. > So add a threshold and go for high allocation directly if the required > size is too large. The value of threshold is set as the half of > the low memory. > > We can also use "crashkernel=X,high" to select a high region above > DMA zone, which also tries to allocate at least 256M low memory in > DMA zone automatically. > "crashkernel=Y,low" can be used to allocate specified size low memory. > For non-RPi4 platforms, change DMA zone memtioned above to DMA32 zone. > > When reserving crashkernel in high memory, some low memory is reserved > for crash dump kernel devices. So there may be two regions reserved for > crash dump kernel. > In order to distinct from the high region and make no effect to the use > of existing kexec-tools, rename the low region as "Crash kernel (low)", > and pass the low region by reusing DT property > "linux,usable-memory-range". We made the low memory region as the last > range of "linux,usable-memory-range" to keep compatibility with existing > user-space and older kdump kernels. > > Besides, we need to modify kexec-tools: > arm64: support more than one crash kernel regions(see [1]) > > Another update is document about DT property 'linux,usable-memory-range': > schemas: update 'linux,usable-memory-range' node schema(see [2]) > > This patchset contains the following nine patches: > 0001-x86-kdump-move-CRASH_ALIGN-to-2M.patch > 0002-x86-kdump-make-the-lower-bound-of-crash-kernel-reser.patch > 0003-x86-kdump-use-macro-CRASH_ADDR_LOW_MAX-in-functions-.patch > 0004-x86-kdump-move-reserve_crashkernel-_low-into-crash_c.patch > 0005-arm64-kdump-introduce-some-macroes-for-crash-kernel-.patch > 0006-arm64-kdump-reimplement-crashkernel-X.patch > 0007-kdump-add-threshold-for-the-required-memory.patch > 0008-arm64-kdump-add-memory-for-devices-by-DT-property-li.patch > 0009-kdump-update-Documentation-about-crashkernel.patch > > 0001-0003 are some x86 cleanups which prepares for making > functionsreserve_crashkernel[_low]() generic. > > 0004 makes functions reserve_crashkernel[_low]() generic. > 0005-0006 reimplements crashkernel=X. > 0007 adds threshold for the required memory. > 0008 adds memory for devices by DT property linux,usable-memory-range. > 0009 updates the doc. Hi Catalin and Dave, Any other suggestions about this patchset? Let me know if you have any questions. Thanks, Chen Zhou > > Changes since [v11] > - Rebased on top of 5.9-rc4. > - Make the function reserve_crashkernel() of x86 generic. > Suggested by Catalin, make the function reserve_crashkernel() of x86 generic > and arm64 use the generic version to reimplement crashkernel=X. > > Changes since [v10] > - Reimplement crashkernel=X suggested by Catalin, Many thanks to Catalin. > > Changes since [v9] > - Patch 1 add Acked-by from Dave. > - Update patch 5 according to Dave's comments. > - Update chosen schema. > > Changes since [v8] > - Reuse DT property "linux,usable-memory-range". > Suggested by Rob, reuse DT property "linux,usable-memory-range" to pass the low > memory region. > - Fix kdump broken with ZONE_DMA reintroduced. > - Update chosen schema. > > Changes since [v7] > - Move x86 CRASH_ALIGN to 2M > Suggested by Dave and do some test, move x86 CRASH_ALIGN to 2M. > - Update Documentation/devicetree/bindings/chosen.txt. > Add corresponding documentation to Documentation/devicetree/bindings/chosen.txt > suggested by Arnd. > - Add Tested-by from Jhon and pk. > > Changes since [v6] > - Fix build errors reported by kbuild test robot. > > Changes since [v5] > - Move reserve_crashkernel_low() into kernel/crash_core.c. > - Delete crashkernel=X,high. > - Modify crashkernel=X,low. > If crashkernel=X,low is specified simultaneously, reserve spcified size low > memory for crash kdump kernel devices firstly and then reserve memory above 4G. > In addition, rename crashk_low_res as "Crash kernel (low)" for arm64, and then > pass to crash dump kernel by DT property "linux,low-memory-range". > - Update Documentation/admin-guide/kdump/kdump.rst. > > Changes since [v4] > - Reimplement memblock_cap_memory_ranges for multiple ranges by Mike. > > Changes since [v3] > - Add memblock_cap_memory_ranges back for multiple ranges. > - Fix some compiling warnings. > > Changes since [v2] > - Split patch "arm64: kdump: support reserving crashkernel above 4G" as > two. Put "move reserve_crashkernel_low() into kexec_core.c" in a separate > patch. > > Changes since [v1]: > - Move common reserve_crashkernel_low() code into kernel/kexec_core.c. > - Remove memblock_cap_memory_ranges() i added in v1 and implement that > in fdt_enforce_memory_region(). > There are at most two crash kernel regions, for two crash kernel regions > case, we cap the memory range [min(regs[*].start), max(regs[*].end)] > and then remove the memory range in the middle. > > [1]: http://lists.infradead.org/pipermail/kexec/2020-June/020737.html > [2]: https://github.com/robherring/dt-schema/pull/19 > [v1]: https://lkml.org/lkml/2019/4/2/1174 > [v2]: https://lkml.org/lkml/2019/4/9/86 > [v3]: https://lkml.org/lkml/2019/4/9/306 > [v4]: https://lkml.org/lkml/2019/4/15/273 > [v5]: https://lkml.org/lkml/2019/5/6/1360 > [v6]: https://lkml.org/lkml/2019/8/30/142 > [v7]: https://lkml.org/lkml/2019/12/23/411 > [v8]: https://lkml.org/lkml/2020/5/21/213 > [v9]: https://lkml.org/lkml/2020/6/28/73 > [v10]: https://lkml.org/lkml/2020/7/2/1443 > [v11]: https://lkml.org/lkml/2020/8/1/150 > > Chen Zhou (9): > x86: kdump: move CRASH_ALIGN to 2M > x86: kdump: make the lower bound of crash kernel reservation > consistent > x86: kdump: use macro CRASH_ADDR_LOW_MAX in functions > reserve_crashkernel[_low]() > x86: kdump: move reserve_crashkernel[_low]() into crash_core.c > arm64: kdump: introduce some macroes for crash kernel reservation > arm64: kdump: reimplement crashkernel=X > kdump: add threshold for the required memory > arm64: kdump: add memory for devices by DT property > linux,usable-memory-range > kdump: update Documentation about crashkernel > > Documentation/admin-guide/kdump/kdump.rst | 25 ++- > .../admin-guide/kernel-parameters.txt | 13 +- > arch/arm64/include/asm/kexec.h | 15 ++ > arch/arm64/include/asm/processor.h | 1 + > arch/arm64/kernel/setup.c | 13 +- > arch/arm64/mm/init.c | 105 ++++------ > arch/arm64/mm/mmu.c | 4 + > arch/x86/include/asm/kexec.h | 28 +++ > arch/x86/kernel/setup.c | 165 +-------------- > include/linux/crash_core.h | 4 + > include/linux/kexec.h | 2 - > kernel/crash_core.c | 192 ++++++++++++++++++ > kernel/kexec_core.c | 17 -- > 13 files changed, 328 insertions(+), 256 deletions(-) >