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kexec: premit reduction of the reserved memory size

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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
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59
kernel/kexec.c
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@ -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)
{