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* [PATCH v4 1/1] kernel/crash_core: Add crashkernel=auto for vmcore creation
@ 2021-02-23 17:41 Saeed Mirzamohammadi
  2021-02-24  2:07 ` Baoquan He
                   ` (2 more replies)
  0 siblings, 3 replies; 5+ messages in thread
From: Saeed Mirzamohammadi @ 2021-02-23 17:41 UTC (permalink / raw)
  Cc: linux-doc, Peter Zijlstra (Intel), Christian Brauner, Ingo Molnar,
	Baoquan He, Jonathan Corbet, YiFei Zhu, Masahiro Yamada,
	Sami Tolvanen, Dave Young, Vivek Goyal, John Donnelly, Kees Cook,
	Paul E. McKenney, saeed.mirzamohammadi, Andrey Konovalov,
	Frederic Weisbecker, Guilherme G. Piccoli,
	Steven Rostedt (VMware), Josh Poimboeuf, Thomas Gleixner,
	Stephen Boyd, Randy Dunlap, kexec, linux-kernel,
	Mauro Carvalho Chehab, Colin Ian King, Andrew Morton,
	Mike Rapoport, Mike Kravetz

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@oracle.com>
Signed-off-by: John Donnelly <john.p.donnelly@oracle.com>
Tested-by: John Donnelly <john.p.donnelly@oracle.com>
---
 Documentation/admin-guide/kdump/kdump.rst     |  3 ++-
 .../admin-guide/kernel-parameters.txt         |  6 ++++++
 arch/Kconfig                                  | 20 +++++++++++++++++++
 kernel/crash_core.c                           |  7 +++++++
 4 files changed, 35 insertions(+), 1 deletion(-)

diff --git a/Documentation/admin-guide/kdump/kdump.rst b/Documentation/admin-guide/kdump/kdump.rst
index 75a9dd98e76e..ae030111e22a 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 9e3cdb271d06..a5deda5c85fe 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -747,6 +747,12 @@
 			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 24862d15f3a3..23d047548772 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -14,6 +14,26 @@ menu "General architecture-dependent options"
 config CRASH_CORE
 	bool
 
+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
+
 config KEXEC_CORE
 	select CRASH_CORE
 	bool
diff --git a/kernel/crash_core.c b/kernel/crash_core.c
index 825284baaf46..90f9e4bb6704 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


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Thread overview: 5+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2021-02-23 17:41 [PATCH v4 1/1] kernel/crash_core: Add crashkernel=auto for vmcore creation Saeed Mirzamohammadi
2021-02-24  2:07 ` Baoquan He
2021-02-24  6:21 ` Kairui Song
2021-02-26  0:38 ` Dave Young
2021-03-02 23:05   ` john.p.donnelly

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