Re: [PATCH v3 1/1] kernel/crash_core: Add crashkernel=auto for vmcore creation
From: john . p . donnelly
Date: Mon Feb 22 2021 - 21:06:09 EST
On 2/17/21 8:02 PM, Baoquan He wrote:
On 02/11/21 at 10:08am, Saeed Mirzamohammadi wrote:
This adds crashkernel=auto feature to configure reserved memory for
vmcore creation. CONFIG_CRASH_AUTO_STR is defined to be set for
different kernel distributions and different archs based on their
needs.
Signed-off-by: Saeed Mirzamohammadi <saeed.mirzamohammadi@xxxxxxxxxx>
Signed-off-by: John Donnelly <john.p.donnelly@xxxxxxxxxx>
Tested-by: John Donnelly <john.p.donnelly@xxxxxxxxxx>
---
Documentation/admin-guide/kdump/kdump.rst | 3 ++-
.../admin-guide/kernel-parameters.txt | 6 +++++
arch/Kconfig | 24 +++++++++++++++++++
kernel/crash_core.c | 7 ++++++
4 files changed, 39 insertions(+), 1 deletion(-)
diff --git a/Documentation/admin-guide/kdump/kdump.rst b/Documentation/admin-guide/kdump/kdump.rst
index 2da65fef2a1c..e55cdc404c6b 100644
--- a/Documentation/admin-guide/kdump/kdump.rst
+++ b/Documentation/admin-guide/kdump/kdump.rst
@@ -285,7 +285,8 @@ This would mean:
2) if the RAM size is between 512M and 2G (exclusive), then reserve 64M
3) if the RAM size is larger than 2G, then reserve 128M
-
+Or you can use crashkernel=auto to choose the crash kernel memory size
+based on the recommended configuration set for each arch.
Boot into System Kernel
=======================
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 7d4e523646c3..aa2099465458 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -736,6 +736,12 @@
a memory unit (amount[KMG]). See also
Documentation/admin-guide/kdump/kdump.rst for an example.
+ crashkernel=auto
+ [KNL] This parameter will set the reserved memory for
+ the crash kernel based on the value of the CRASH_AUTO_STR
+ that is the best effort estimation for each arch. See also
+ arch/Kconfig for further details.
+
crashkernel=size[KMG],high
[KNL, X86-64] range could be above 4G. Allow kernel
to allocate physical memory region from top, so could
diff --git a/arch/Kconfig b/arch/Kconfig
index af14a567b493..f87c88ffa2f8 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -14,6 +14,30 @@ menu "General architecture-dependent options"
config CRASH_CORE
bool
+if CRASH_CORE
+
+config CRASH_AUTO_STR
+ string "Memory reserved for crash kernel"
+ depends on CRASH_CORE
+ default "1G-64G:128M,64G-1T:256M,1T-:512M"
+ help
+ This configures the reserved memory dependent
+ on the value of System RAM. The syntax is:
+ crashkernel=<range1>:<size1>[,<range2>:<size2>,...][@offset]
+ range=start-[end]
+
+ For example:
+ crashkernel=512M-2G:64M,2G-:128M
+
+ This would mean:
+
+ 1) if the RAM is smaller than 512M, then don't reserve anything
+ (this is the "rescue" case)
+ 2) if the RAM size is between 512M and 2G (exclusive), then reserve 64M
+ 3) if the RAM size is larger than 2G, then reserve 128M
+
+endif # CRASH_CORE
Wondering if this CRASH_CORE ifdeffery is a little redundent here
since CRASH_CORE dependency has been added. Except of this, I like this
patch. As we discussed in private threads, we can try to push it into
mainline and continue improving later.
Hi,
Are we good to move forward with this and apply it now?
Dave Young acked it.
Thank you,
John.
(Note - I am currently not on any vger.kernel.org dlist at the moment so
please cc me ).
+
config KEXEC_CORE
select CRASH_CORE
bool
diff --git a/kernel/crash_core.c b/kernel/crash_core.c
index 106e4500fd53..ab0a2b4b1ffa 100644
--- a/kernel/crash_core.c
+++ b/kernel/crash_core.c
@@ -7,6 +7,7 @@
#include <linux/crash_core.h>
#include <linux/utsname.h>
#include <linux/vmalloc.h>
+#include <linux/kexec.h>
#include <asm/page.h>
#include <asm/sections.h>
@@ -250,6 +251,12 @@ static int __init __parse_crashkernel(char *cmdline,
if (suffix)
return parse_crashkernel_suffix(ck_cmdline, crash_size,
suffix);
+#ifdef CONFIG_CRASH_AUTO_STR
+ if (strncmp(ck_cmdline, "auto", 4) == 0) {
+ ck_cmdline = CONFIG_CRASH_AUTO_STR;
+ pr_info("Using crashkernel=auto, the size chosen is a best effort estimation.\n");
+ }
+#endif
/*
* if the commandline contains a ':', then that's the extended
* syntax -- if not, it must be the classic syntax
--
2.27.0