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authorAmerigo Wang <amwang@redhat.com>2009-12-15 16:47:46 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2009-12-16 07:20:13 -0800
commit06a7f711246b081afc21fff859f1003f1f2a0fbc (patch)
treeaece49693ad751923ce71387201d3c3e6214e335
parent1f2c19f8c959c1d0ccd3e33b1f480593b66d95dd (diff)
downloadlinux-sh-06a7f711246b081afc21fff859f1003f1f2a0fbc.tar.gz
kexec: premit reduction of the reserved memory size
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@redhat.com> Cc: Neil Horman <nhorman@redhat.com> Acked-by: Eric W. Biederman <ebiederm@xmission.com> Cc: Andi Kleen <andi@firstfloor.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--include/linux/kexec.h2
-rw-r--r--kernel/kexec.c59
-rw-r--r--kernel/ksysfs.c21
3 files changed, 82 insertions, 0 deletions
diff --git a/include/linux/kexec.h b/include/linux/kexec.h
index adc34f2c6eff..c356b6914ffd 100644
--- a/include/linux/kexec.h
+++ b/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 --git a/kernel/kexec.c b/kernel/kexec.c
index f336e2107f98..433e9fcc1fc5 100644
--- a/kernel/kexec.c
+++ b/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 --git a/kernel/ksysfs.c b/kernel/ksysfs.c
index 528dd78e7e7e..3feaf5a74514 100644
--- a/kernel/ksysfs.c
+++ b/kernel/ksysfs.c
@@ -100,6 +100,26 @@ static ssize_t kexec_crash_loaded_show(struct kobject *kobj,
}
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, "%zu\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