[patch 3/9] kernel/crash_core: suppress unknown crashkernel parameter warning

[Andrew Morton <akpm@linux-foundation.org>]

From: Philipp Rudo <prudo@redhat.com>
Subject: kernel/crash_core: suppress unknown crashkernel parameter warning

When booting with crashkernel= on the kernel command line a warning
similar to

[    0.038294] Kernel command line: ro console=ttyS0 crashkernel=256M
[    0.038353] Unknown kernel command line parameters "crashkernel=256M", will be passed to user space.

is printed.  This comes from crashkernel= being parsed independent from
the kernel parameter handling mechanism.  So the code in init/main.c
doesn't know that crashkernel= is a valid kernel parameter and prints this
incorrect warning.  Suppress the warning by adding a dummy early_param
handler for crashkernel=.

Link: https://lkml.kernel.org/r/20211208133443.6867-1-prudo@redhat.com
Fixes: 86d1919a4fb0 ("init: print out unknown kernel parameters")
Signed-off-by: Philipp Rudo <prudo@redhat.com>
Acked-by: Baoquan He <bhe@redhat.com>
Cc: Andrew Halaney <ahalaney@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 kernel/crash_core.c |   11 +++++++++++
 1 file changed, 11 insertions(+)

--- a/kernel/crash_core.c~kernel-crash_core-suppress-unknown-crashkernel-parameter-warning
+++ a/kernel/crash_core.c
@@ -6,6 +6,7 @@
 
 #include <linux/buildid.h>
 #include <linux/crash_core.h>
+#include <linux/init.h>
 #include <linux/utsname.h>
 #include <linux/vmalloc.h>
 
@@ -295,6 +296,16 @@ int __init parse_crashkernel_low(char *c
 				"crashkernel=", suffix_tbl[SUFFIX_LOW]);
 }
 
+/*
+ * Add a dummy early_param handler to mark crashkernel= as a known command line
+ * parameter and suppress incorrect warnings in init/main.c.
+ */
+static int __init parse_crashkernel_dummy(char *arg)
+{
+	return 0;
+}
+early_param("crashkernel", parse_crashkernel_dummy);
+
 Elf_Word *append_elf_note(Elf_Word *buf, char *name, unsigned int type,
 			  void *data, size_t data_len)
 {
_