On 09/27/2010 08:46 PM, H. Peter Anvin wrote:
> On 09/27/2010 05:53 PM, Vivek Goyal wrote:
>>
>> Actually, hardcoding the upper limit to 4G is probably not the best idea.
>> Kexec loads the the relocatable binary (purgatory) and I remember that
>> one of the generated relocation type was signed 32 bit and allowed max value
>> to be 2G only. So IIRC, purgatory code always needed to be loaded below 2G.
>>
>> I liked HPA's other idea better of introducing memblock_find_in_range_lowest()
>> so that we search bottom up and not rely on a specific upper limit.
>>
>
> No, it's just another crappy hack which is broken in the same way. It's
> better than open-coding, but it's still a hack.
>
> The Right Thing[TM] to do is for kexec to communicate the topmost
> address it wants to this code, so it has both the upper and the lower
> boundaries available to it instead of just one.
hope you are happy with this one.
[PATCH -v5] x86, memblock: Fix crashkernel allocation
Cai Qian found crashkernel is broken with x86 memblock changes
1. crashkernel=128M at 32M always reported that range is used, even first kernel is small
no one use that range
2. always get following report when using "kexec -p"
Could not find a free area of memory of a000 bytes...
locate_hole failed
The root cause is that generic memblock_find_in_range() will try to get range from top_down.
But crashkernel do need from low and specified range.
Let's limit the target range with rash_base + crash_size to make sure that
We get range from bottom.
-v5: use DEFAULT_BZIMAGE_ADDR_MAX to limit area that could be used by bzImge.
also second try for vmlinux or new kexec tools will use bzImage 64bit entry
Reported-and-Bisected-by: CAI Qian <caiqian at redhat.com>
Signed-off-by: Yinghai Lu <yinghai at kernel.org>
---
arch/x86/kernel/setup.c | 24 ++++++++++++++++++------
1 file changed, 18 insertions(+), 6 deletions(-)
Index: linux-2.6/arch/x86/kernel/setup.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/setup.c
+++ linux-2.6/arch/x86/kernel/setup.c
@@ -501,6 +501,7 @@ static inline unsigned long long get_tot
return total << PAGE_SHIFT;
}
+#define DEFAULT_BZIMAGE_ADDR_MAX 0x37FFFFFF
static void __init reserve_crashkernel(void)
{
unsigned long long total_mem;
@@ -518,17 +519,28 @@ static void __init reserve_crashkernel(v
if (crash_base <= 0) {
const unsigned long long alignment = 16<<20; /* 16M */
- crash_base = memblock_find_in_range(alignment, ULONG_MAX, crash_size,
- alignment);
+ /*
+ * Assume half crash_size is for bzImage
+ * kexec want bzImage is below DEFAULT_BZIMAGE_ADDR_MAX
+ */
+ crash_base = memblock_find_in_range(alignment,
+ DEFAULT_BZIMAGE_ADDR_MAX + crash_size/2,
+ crash_size, alignment);
+
if (crash_base == MEMBLOCK_ERROR) {
- pr_info("crashkernel reservation failed - No suitable area found.\n");
- return;
+ crash_base = memblock_find_in_range(alignment,
+ ULONG_MAX, crash_size, alignment);
+
+ if (crash_base == MEMBLOCK_ERROR) {
+ pr_info("crashkernel reservation failed - No suitable area found.\n");
+ return;
+ }
}
} else {
unsigned long long start;
- start = memblock_find_in_range(crash_base, ULONG_MAX, crash_size,
- 1<<20);
+ start = memblock_find_in_range(crash_base,
+ crash_base + crash_size, crash_size, 1<<20);
if (start != crash_base) {
pr_info("crashkernel reservation failed - memory is in use.\n");
return;
