[PATCH] crash_dump: remove saved_max_pfn

From: Kairui Song
Date: Mon Mar 30 2020 - 14:16:32 EST


This variable is no longer used.

saved_max_pfn was originally introduce in commit 92aa63a5a1bf ("[PATCH]
kdump: Retrieve saved max pfn"), used to make sure that user does not
try to read the physical memory beyond saved_max_pfn. But since
commit 921d58c0e699 ("vmcore: remove saved_max_pfn check")
it's no longer used for the check.

Only user left is Calary IOMMU, which start using it from
commit 95b68dec0d52 ("calgary iommu: use the first kernels TCE tables
in kdump"). But again, recently in commit 90dc392fc445 ("x86: Remove
the calgary IOMMU driver"), Calary IOMMU is removed and this variable
no longer have any user.

So just remove it.

Signed-off-by: Kairui Song <kasong@xxxxxxxxxx>
---
arch/x86/kernel/e820.c | 8 --------
include/linux/crash_dump.h | 2 --
kernel/crash_dump.c | 6 ------
3 files changed, 16 deletions(-)

diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c
index c5399e80c59c..4d13c57f370a 100644
--- a/arch/x86/kernel/e820.c
+++ b/arch/x86/kernel/e820.c
@@ -910,14 +910,6 @@ static int __init parse_memmap_one(char *p)
return -EINVAL;

if (!strncmp(p, "exactmap", 8)) {
-#ifdef CONFIG_CRASH_DUMP
- /*
- * If we are doing a crash dump, we still need to know
- * the real memory size before the original memory map is
- * reset.
- */
- saved_max_pfn = e820__end_of_ram_pfn();
-#endif
e820_table->nr_entries = 0;
userdef = 1;
return 0;
diff --git a/include/linux/crash_dump.h b/include/linux/crash_dump.h
index 4664fc1871de..bc156285d097 100644
--- a/include/linux/crash_dump.h
+++ b/include/linux/crash_dump.h
@@ -97,8 +97,6 @@ extern void unregister_oldmem_pfn_is_ram(void);
static inline bool is_kdump_kernel(void) { return 0; }
#endif /* CONFIG_CRASH_DUMP */

-extern unsigned long saved_max_pfn;
-
/* Device Dump information to be filled by drivers */
struct vmcoredd_data {
char dump_name[VMCOREDD_MAX_NAME_BYTES]; /* Unique name of the dump */
diff --git a/kernel/crash_dump.c b/kernel/crash_dump.c
index 9c23ae074b40..92da32275af5 100644
--- a/kernel/crash_dump.c
+++ b/kernel/crash_dump.c
@@ -5,12 +5,6 @@
#include <linux/errno.h>
#include <linux/export.h>

-/*
- * If we have booted due to a crash, max_pfn will be a very low value. We need
- * to know the amount of memory that the previous kernel used.
- */
-unsigned long saved_max_pfn;
-
/*
* stores the physical address of elf header of crash image
*
--
2.25.1