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 <[email protected]>
Cc: Neil Horman <[email protected]>
Acked-by: Eric W. Biederman <[email protected]>
Cc: Andi Kleen <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
This commit is contained in:
Amerigo Wang 2009-12-15 16:47:46 -08:00 • committed by Linus Torvalds
commit 06a7f71124
3 changed files with 82 additions and 0 deletions

View file

@ -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