Re: [PATCH v4 1/1] kernel/crash_core: Add crashkernel=auto for vmcore creation
From: Dave Young
Date: Thu Feb 25 2021 - 19:41:03 EST
On 02/23/21 at 09:41am, Saeed Mirzamohammadi wrote:
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This adds crashkernel=auto feature to configure reserved memory for
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vmcore creation. CONFIG_CRASH_AUTO_STR is defined to be set for
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different kernel distributions and different archs based on their
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needs.
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Signed-off-by: Saeed Mirzamohammadi <saeed.mirzamohammadi@xxxxxxxxxx>
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Signed-off-by: John Donnelly <john.p.donnelly@xxxxxxxxxx>
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Tested-by: John Donnelly <john.p.donnelly@xxxxxxxxxx>
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---
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Documentation/admin-guide/kdump/kdump.rst | 3 ++-
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.../admin-guide/kernel-parameters.txt | 6 ++++++
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arch/Kconfig | 20 +++++++++++++++++++
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kernel/crash_core.c | 7 +++++++
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4 files changed, 35 insertions(+), 1 deletion(-)
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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 75a9dd98e76e..ae030111e22a 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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@@ -285,7 +285,8 @@ 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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>
-
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+Or you can use crashkernel=auto to choose the crash kernel memory size
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+based on the recommended configuration set for each arch.
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>
Boot into System Kernel
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=======================
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diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
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index 9e3cdb271d06..a5deda5c85fe 100644
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--- a/Documentation/admin-guide/kernel-parameters.txt
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+++ b/Documentation/admin-guide/kernel-parameters.txt
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@@ -747,6 +747,12 @@
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a memory unit (amount[KMG]). See also
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Documentation/admin-guide/kdump/kdump.rst for an example.
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+ crashkernel=auto
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+ [KNL] This parameter will set the reserved memory for
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+ the crash kernel based on the value of the CRASH_AUTO_STR
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+ that is the best effort estimation for each arch. See also
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+ arch/Kconfig for further details.
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+
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crashkernel=size[KMG],high
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[KNL, X86-64] range could be above 4G. Allow kernel
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to allocate physical memory region from top, so could
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diff --git a/arch/Kconfig b/arch/Kconfig
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index 24862d15f3a3..23d047548772 100644
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--- a/arch/Kconfig
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+++ b/arch/Kconfig
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@@ -14,6 +14,26 @@ menu "General architecture-dependent options"
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config CRASH_CORE
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bool
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+config CRASH_AUTO_STR
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+ string "Memory reserved for crash kernel"
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+ depends on CRASH_CORE
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+ default "1G-64G:128M,64G-1T:256M,1T-:512M"
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+ help
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+ This configures the reserved memory dependent
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+ on the value of System RAM. The syntax is:
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+ crashkernel=<range1>:<size1>[,<range2>:<size2>,...][@offset]
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+ range=start-[end]
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+
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+ For example:
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+ crashkernel=512M-2G:64M,2G-:128M
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+
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+ This would mean:
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+
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+ 1) if the RAM is smaller than 512M, then don't reserve anything
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+ (this is the "rescue" case)
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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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+
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config KEXEC_CORE
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select CRASH_CORE
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bool
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diff --git a/kernel/crash_core.c b/kernel/crash_core.c
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index 825284baaf46..90f9e4bb6704 100644
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--- a/kernel/crash_core.c
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+++ b/kernel/crash_core.c
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@@ -7,6 +7,7 @@
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#include <linux/crash_core.h>
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#include <linux/utsname.h>
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#include <linux/vmalloc.h>
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+#include <linux/kexec.h>
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#include <asm/page.h>
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#include <asm/sections.h>
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@@ -250,6 +251,12 @@ 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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+#ifdef CONFIG_CRASH_AUTO_STR
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+ if (strncmp(ck_cmdline, "auto", 4) == 0) {
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+ ck_cmdline = CONFIG_CRASH_AUTO_STR;
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+ pr_info("Using crashkernel=auto, the size chosen is a best effort estimation.\n");
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+ }
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+#endif
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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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2.27.0
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Acked-by: Dave Young <dyoung@xxxxxxxxxx>
Thanks
Dave