The patch titled
kexec: premit reduction of the reserved memory size
has been added to the -mm tree. Its filename is
kexec-premit-reduction-of-the-reserved-memory-size.patch
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------------------------------------------------------
Subject: kexec: premit reduction of the reserved memory size
From: Amerigo Wang <amwang@xxxxxxxxxx>
Implement shrinking the reserved memory for crash kernel, if it is more
than enough.
For example, if you have already reserved 128M, now you just want 100M,
you can do:
# echo $((100*1024*1024)) > /sys/kernel/kexec_crash_size
Note, you can only do this before loading the crash kernel.
Signed-off-by: WANG Cong <amwang@xxxxxxxxxx>
Cc: Neil Horman <nhorman@xxxxxxxxxx>
Acked-by: Eric W. Biederman <ebiederm@xxxxxxxxxxxx>
Cc: Andi Kleen <andi@xxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/kexec.h | 2 +
kernel/kexec.c | 59 ++++++++++++++++++++++++++++++++++++++++
kernel/ksysfs.c | 21 ++++++++++++++
3 files changed, 82 insertions(+)
diff -puN include/linux/kexec.h~kexec-premit-reduction-of-the-reserved-memory-size include/linux/kexec.h
--- a/include/linux/kexec.h~kexec-premit-reduction-of-the-reserved-memory-size
+++ a/include/linux/kexec.h
@@ -206,6 +206,8 @@ extern size_t vmcoreinfo_max_size;
int __init parse_crashkernel(char *cmdline, unsigned long long system_ram,
unsigned long long *crash_size, unsigned long long *crash_base);
+int crash_shrink_memory(unsigned long new_size);
+size_t crash_get_memory_size(void);
#else /* !CONFIG_KEXEC */
struct pt_regs;
diff -puN kernel/kexec.c~kexec-premit-reduction-of-the-reserved-memory-size kernel/kexec.c
--- a/kernel/kexec.c~kexec-premit-reduction-of-the-reserved-memory-size
+++ a/kernel/kexec.c
@@ -31,6 +31,7 @@
#include <linux/cpu.h>
#include <linux/console.h>
#include <linux/vmalloc.h>
+#include <linux/swap.h>
#include <asm/page.h>
#include <asm/uaccess.h>
@@ -1082,6 +1083,64 @@ void crash_kexec(struct pt_regs *regs)
}
}
+size_t crash_get_memory_size(void)
+{
+ size_t size;
+ mutex_lock(&kexec_mutex);
+ size = crashk_res.end - crashk_res.start + 1;
+ mutex_unlock(&kexec_mutex);
+ return size;
+}
+
+static void free_reserved_phys_range(unsigned long begin, unsigned long end)
+{
+ unsigned long addr;
+
+ for (addr = begin; addr < end; addr += PAGE_SIZE) {
+ ClearPageReserved(pfn_to_page(addr >> PAGE_SHIFT));
+ init_page_count(pfn_to_page(addr >> PAGE_SHIFT));
+ free_page((unsigned long)__va(addr));
+ totalram_pages++;
+ }
+}
+
+int crash_shrink_memory(unsigned long new_size)
+{
+ int ret = 0;
+ unsigned long start, end;
+
+ mutex_lock(&kexec_mutex);
+
+ if (kexec_crash_image) {
+ ret = -ENOENT;
+ goto unlock;
+ }
+ start = crashk_res.start;
+ end = crashk_res.end;
+
+ if (new_size >= end - start + 1) {
+ ret = -EINVAL;
+ if (new_size == end - start + 1)
+ ret = 0;
+ goto unlock;
+ }
+
+ start = roundup(start, PAGE_SIZE);
+ end = roundup(start + new_size, PAGE_SIZE);
+
+ free_reserved_phys_range(end, crashk_res.end);
+
+ if (start == end) {
+ crashk_res.end = end;
+ release_resource(&crashk_res);
+ } else
+ crashk_res.end = end - 1;
+
+unlock:
+ mutex_unlock(&kexec_mutex);
+ return ret;
+}
+
static u32 *append_elf_note(u32 *buf, char *name, unsigned type, void *data,
size_t data_len)
{
diff -puN kernel/ksysfs.c~kexec-premit-reduction-of-the-reserved-memory-size kernel/ksysfs.c
--- a/kernel/ksysfs.c~kexec-premit-reduction-of-the-reserved-memory-size
+++ a/kernel/ksysfs.c
@@ -100,6 +100,26 @@ static ssize_t kexec_crash_loaded_show(s
}
KERNEL_ATTR_RO(kexec_crash_loaded);
+static ssize_t kexec_crash_size_show(struct kobject *kobj,
+ struct kobj_attribute *attr, char *buf)
+{
+ return sprintf(buf, "%lu\n", crash_get_memory_size());
+}
+static ssize_t kexec_crash_size_store(struct kobject *kobj,
+ struct kobj_attribute *attr,
+ const char *buf, size_t count)
+{
+ unsigned long cnt;
+ int ret;
+
+ if (strict_strtoul(buf, 0, &cnt))
+ return -EINVAL;
+
+ ret = crash_shrink_memory(cnt);
+ return ret < 0 ? ret : count;
+}
+KERNEL_ATTR_RW(kexec_crash_size);
+
static ssize_t vmcoreinfo_show(struct kobject *kobj,
struct kobj_attribute *attr, char *buf)
{
@@ -147,6 +167,7 @@ static struct attribute * kernel_attrs[]
#ifdef CONFIG_KEXEC
&kexec_loaded_attr.attr,
&kexec_crash_loaded_attr.attr,
+ &kexec_crash_size_attr.attr,
&vmcoreinfo_attr.attr,
#endif
NULL
_
Patches currently in -mm which might be from amwang@xxxxxxxxxx are
linux-next.patch
xtensa-use-generic-sys_pipe.patch
rwsem-spinlock-remove-useless-function-exports.patch
rwsem-fix-rwsem_is_locked-bugs.patch
rwsem-fix-rwsem_is_locked-bugs-fix.patch
kallsyms-remove-deprecated-print_fn_descriptor_symbol.patch
kexec-premit-reduction-of-the-reserved-memory-size.patch
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