4fdfe982ae
* Tue May 05 2020 CKI@GitLab <cki-project@redhat.com> [5.7.0-0.rc4.20200505git47cf1b422e60.1]
- 47cf1b422e60 rebase
- Build ARK against ELN (Don Zickus)
- Updated changelog for the release based on v5.7-rc4 ("CKI@GitLab")
Resolves: rhbz#
Signed-off-by: Justin M. Forbes <jforbes@fedoraproject.org>
190 lines
8.7 KiB
Diff
190 lines
8.7 KiB
Diff
From 35b5bc3c0ae5a8665954bc7ab8500c254e8837d3 Mon Sep 17 00:00:00 2001
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From: Jeremy Cline <jcline@redhat.com>
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Date: Tue, 23 Jul 2019 15:24:30 +0000
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Subject: [PATCH] kdump: add support for crashkernel=auto
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Rebased for v5.3-rc1 because the documentation has moved.
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Message-id: <20180604013831.574215750@redhat.com>
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Patchwork-id: 8166
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O-Subject: [kernel team] [PATCH RHEL8.0 V2 2/2] kdump: add support for crashkernel=auto
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Bugzilla: 1507353
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RH-Acked-by: Don Zickus <dzickus@redhat.com>
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RH-Acked-by: Baoquan He <bhe@redhat.com>
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RH-Acked-by: Pingfan Liu <piliu@redhat.com>
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Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1507353
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Build: https://brewweb.engineering.redhat.com/brew/taskinfo?taskID=16534135
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Tested: ppc64le, x86_64 with several memory sizes.
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kdump qe tested 160M on various x86 machines in lab.
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We continue to provide crashkernel=auto like we did in RHEL6
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and RHEL7, this will simplify the kdump deployment for common
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use cases that kdump just works with the auto reserved values.
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But this is still a best effort estimation, we can not know the
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exact memory requirement because it depends on a lot of different
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factors.
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The implementation of crashkernel=auto is simplified as a wrapper
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to use below kernel cmdline:
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x86_64: crashkernel=1G-64G:160M,64G-1T:256M,1T-:512M
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s390x: crashkernel=4G-64G:160M,64G-1T:256M,1T-:512M
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arm64: crashkernel=2G-:512M
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ppc64: crashkernel=2G-4G:384M,4G-16G:512M,16G-64G:1G,64G-128G:2G,128G-:4G
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The difference between this way and the old implementation in
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RHEL6/7 is we do not scale the crash reserved memory size according
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to system memory size anymore.
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Latest effort to move upstream is below thread:
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https://lkml.org/lkml/2018/5/20/262
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But unfortunately it is still unlikely to be accepted, thus we
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will still use a RHEL only patch in RHEL8.
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Copied old patch description about the history reason see below:
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'''
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Non-upstream explanations:
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Besides "crashkenrel=X@Y" format, upstream also has advanced
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"crashkernel=range1:size1[,range2:size2,...][@offset]", and
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"crashkernel=X,high{low}" formats, but they need more careful
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manual configuration, and have different values for different
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architectures.
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Most of the distributions use the standard "crashkernel=X@Y"
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upstream format, and use crashkernel range format for advanced
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scenarios, heavily relying on the user's involvement.
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While "crashkernel=auto" is redhat's special feature, it exists
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and has been used as the default boot cmdline since 2008 rhel6.
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It does not require users to figure out how many crash memory
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size for their systems, also has been proved to be able to work
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pretty well for common scenarios.
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"crashkernel=auto" was tested/based on rhel-related products, as
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we have stable kernel configurations which means more or less
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stable memory consumption. In 2014 we tried to post them again to
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upstream but NACKed by people because they think it's not general
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and unnecessary, users can specify their own values or do that by
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scripts. However our customers insist on having it added to rhel.
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Also see one previous discussion related to this backport to Pegas:
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On 10/17/2016 at 10:15 PM, Don Zickus wrote:
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> On Fri, Oct 14, 2016 at 10:57:41AM +0800, Dave Young wrote:
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>> Don, agree with you we should evaluate them instead of just inherit
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>> them blindly. Below is what I think about kdump auto memory:
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>> There are two issues for crashkernel=auto in upstream:
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>> 1) It will be seen as a policy which should not go to kernel
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>> 2) It is hard to get a good number for the crash reserved size,
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>> considering various different kernel config options one can setups.
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>> In RHEL we are easier because our supported Kconfig is limited.
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>> I digged the upstream mail archive, but I'm not sure I got all the
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>> information, at least Michael Ellerman was objecting the series for
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>> 1).
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> Yes, I know. Vivek and I have argued about this for years. :-)
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>
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> I had hoped all the changes internally to the makedumpfile would allow
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> the memory configuration to stabilize at a number like 192M or 128M and
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> only in the rare cases extend beyond that.
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>
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> So I always treated that as a temporary hack until things were better.
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> With the hope of every new RHEL release we get smarter and better. :-)
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> Ideally it would be great if we could get the number down to 64M for most
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> cases and just turn it on in Fedora. Maybe someday.... ;-)
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>
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> We can have this conversation when the patch gets reposted/refreshed
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> for upstream on rhkl?
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>
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> Cheers,
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> Don
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We had proposed to drop the historic crashkernel=auto code and move
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to use crashkernel=range:size format and pass them in anaconda.
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The initial reason is crashkernel=range:size works just fine because
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we do not need complex algorithm to scale crashkernel reserved size
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any more. The old linear scaling is mainly for old makedumpfile
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requirements, now it is not necessary.
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But With the new approach, backward compatibility is potentially at risk.
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For e.g. let's consider the following cases:
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1) When we upgrade from an older distribution like rhel-alt-7.4(which
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uses crashkernel=auto) to rhel-alt-7.5 (which uses the crashkernel=xY
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format)
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In this case we can use anaconda scripts for checking
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'crashkernel=auto' in kernel spec and update to the new
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'crashkernel=range:size' format.
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2) When we upgrade from rhel-alt-7.5(which uses crashkernel=xY format)
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to rhel-alt-7.6(which uses crashkernel=xY format), but the x and/or Y
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values are changed in rhel-alt-7.6.
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For example from crashkernel=2G-:160M to crashkernel=2G-:192M, then we have
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no way to determine if the X and/or Y values were distribution
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provided or user specified ones.
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Since it is recommended to give precedence to user-specified values,
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so we cannot do an upgrade in such a case."
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Thus turn back to resolve it in kernel, and add a simpler version
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which just hacks to use the range:size style in code, and make
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rhel-only code easily to maintain.
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'''
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Signed-off-by: Dave Young <dyoung@redhat.com>
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Signed-off-by: Herton R. Krzesinski <herton@redhat.com>
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Upstream Status: RHEL only
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Signed-off-by: Jeremy Cline <jcline@redhat.com>
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---
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Documentation/admin-guide/kdump/kdump.rst | 11 +++++++++++
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kernel/crash_core.c | 14 ++++++++++++++
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2 files changed, 25 insertions(+)
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diff --git a/Documentation/admin-guide/kdump/kdump.rst b/Documentation/admin-guide/kdump/kdump.rst
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index ac7e131d2935..3b3bf30e537d 100644
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--- a/Documentation/admin-guide/kdump/kdump.rst
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+++ b/Documentation/admin-guide/kdump/kdump.rst
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@@ -285,6 +285,17 @@ This would mean:
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2) if the RAM size is between 512M and 2G (exclusive), then reserve 64M
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3) if the RAM size is larger than 2G, then reserve 128M
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+Or you can use crashkernel=auto if you have enough memory. The threshold
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+is 2G on x86_64, arm64, ppc64 and ppc64le. The threshold is 4G for s390x.
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+If your system memory is less than the threshold crashkernel=auto will not
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+reserve memory.
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+
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+The automatically reserved memory size varies based on architecture.
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+The size changes according to system memory size like below:
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+ x86_64: 1G-64G:160M,64G-1T:256M,1T-:512M
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+ s390x: 4G-64G:160M,64G-1T:256M,1T-:512M
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+ arm64: 2G-:512M
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+ ppc64: 2G-4G:384M,4G-16G:512M,16G-64G:1G,64G-128G:2G,128G-:4G
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Boot into System Kernel
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diff --git a/kernel/crash_core.c b/kernel/crash_core.c
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index d631d22089ba..c252221b2f4b 100644
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--- a/kernel/crash_core.c
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+++ b/kernel/crash_core.c
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@@ -258,6 +258,20 @@ static int __init __parse_crashkernel(char *cmdline,
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if (suffix)
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return parse_crashkernel_suffix(ck_cmdline, crash_size,
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suffix);
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+
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+ if (strncmp(ck_cmdline, "auto", 4) == 0) {
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+#ifdef CONFIG_X86_64
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+ ck_cmdline = "1G-64G:160M,64G-1T:256M,1T-:512M";
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+#elif defined(CONFIG_S390)
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+ ck_cmdline = "4G-64G:160M,64G-1T:256M,1T-:512M";
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+#elif defined(CONFIG_ARM64)
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+ ck_cmdline = "2G-:512M";
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+#elif defined(CONFIG_PPC64)
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+ ck_cmdline = "2G-4G:384M,4G-16G:512M,16G-64G:1G,64G-128G:2G,128G-:4G";
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+#endif
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+ pr_info("Using crashkernel=auto, the size choosed is a best effort estimation.\n");
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+ }
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+
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/*
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* if the commandline contains a ':', then that's the extended
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* syntax -- if not, it must be the classic syntax
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--
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2.26.2
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