* [PATCH] kdump x86: fix total mem size calculation for reservation
@ 2012-03-09 8:30 Dave Young
2012-03-10 3:27 ` Cong Wang
0 siblings, 1 reply; 6+ messages in thread
From: Dave Young @ 2012-03-09 8:30 UTC (permalink / raw)
To: linux-kernel, x86, linux, vgoyal
crashkernel reservation need know the total memory size. Current get_total_mem
simply use max_pfn - min_low_pfn. It is wrong because it will including
memory holes in the middle.
Especially for kvm guest with memory > 0xe0000000, there's below in qemu code:
qemu split memory as below:
if (ram_size >= 0xe0000000 ) {
above_4g_mem_size = ram_size - 0xe0000000;
below_4g_mem_size = 0xe0000000;
} else {
below_4g_mem_size = ram_size;
}
So for 4G mem guest, seabios will insert a 512M usable region beyond of 4G.
Thus in above case max_pfn - min_low_pfn will be more than original memsize.
Fixing this issue by using memblock_phys_mem_size() to get the total memsize.
Signed-off-by: Dave Young <dyoung@redhat.com>
---
[Ther's similar code in arm, I'm not sure whether the memblock_phys_mem_size
works with arm or not. If it works I can also update that part of code.]
arch/x86/kernel/setup.c | 12 +-----------
1 file changed, 1 insertion(+), 11 deletions(-)
--- linux-2.6.orig/arch/x86/kernel/setup.c 2012-03-09 11:27:30.000000000 +0800
+++ linux-2.6/arch/x86/kernel/setup.c 2012-03-09 15:41:29.666530976 +0800
@@ -509,16 +509,6 @@ static void __init memblock_x86_reserve_
#ifdef CONFIG_KEXEC
-static inline unsigned long long get_total_mem(void)
-{
- unsigned long long total;
-
- total = max_pfn - min_low_pfn;
- printk("hidave: memsize=%llu\n", memblock_phys_mem_size());
-
- return total << PAGE_SHIFT;
-}
-
/*
* Keep the crash kernel below this limit. On 32 bits earlier kernels
* would limit the kernel to the low 512 MiB due to mapping restrictions.
@@ -537,7 +527,7 @@ static void __init reserve_crashkernel(v
unsigned long long crash_size, crash_base;
int ret;
- total_mem = get_total_mem();
+ total_mem = memblock_phys_mem_size();
ret = parse_crashkernel(boot_command_line, total_mem,
&crash_size, &crash_base);
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] kdump x86: fix total mem size calculation for reservation
2012-03-09 8:30 [PATCH] kdump x86: fix total mem size calculation for reservation Dave Young
@ 2012-03-10 3:27 ` Cong Wang
2012-03-10 4:32 ` Dave Young
2012-03-10 4:56 ` [PATCH v2] " Dave Young
0 siblings, 2 replies; 6+ messages in thread
From: Cong Wang @ 2012-03-10 3:27 UTC (permalink / raw)
To: Dave Young; +Cc: linux-kernel, x86, linux, vgoyal
On 03/09/2012 04:30 PM, Dave Young wrote:
> crashkernel reservation need know the total memory size. Current get_total_mem
> simply use max_pfn - min_low_pfn. It is wrong because it will including
> memory holes in the middle.
>
> Especially for kvm guest with memory> 0xe0000000, there's below in qemu code:
> qemu split memory as below:
> if (ram_size>= 0xe0000000 ) {
> above_4g_mem_size = ram_size - 0xe0000000;
> below_4g_mem_size = 0xe0000000;
> } else {
> below_4g_mem_size = ram_size;
> }
> So for 4G mem guest, seabios will insert a 512M usable region beyond of 4G.
> Thus in above case max_pfn - min_low_pfn will be more than original memsize.
>
> Fixing this issue by using memblock_phys_mem_size() to get the total memsize.
>
Makes sense for me!
> -static inline unsigned long long get_total_mem(void)
> -{
> - unsigned long long total;
> -
> - total = max_pfn - min_low_pfn;
> - printk("hidave: memsize=%llu\n", memblock_phys_mem_size());
This debugging line does not exist... so this patch can't be applied.
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] kdump x86: fix total mem size calculation for reservation
2012-03-10 3:27 ` Cong Wang
@ 2012-03-10 4:32 ` Dave Young
2012-03-10 4:56 ` [PATCH v2] " Dave Young
1 sibling, 0 replies; 6+ messages in thread
From: Dave Young @ 2012-03-10 4:32 UTC (permalink / raw)
To: Cong Wang; +Cc: linux-kernel, x86, linux, vgoyal
On 03/10/2012 11:27 AM, Cong Wang wrote:
> On 03/09/2012 04:30 PM, Dave Young wrote:
>> crashkernel reservation need know the total memory size. Current
>> get_total_mem
>> simply use max_pfn - min_low_pfn. It is wrong because it will including
>> memory holes in the middle.
>>
>> Especially for kvm guest with memory> 0xe0000000, there's below in
>> qemu code:
>> qemu split memory as below:
>> if (ram_size>= 0xe0000000 ) {
>> above_4g_mem_size = ram_size - 0xe0000000;
>> below_4g_mem_size = 0xe0000000;
>> } else {
>> below_4g_mem_size = ram_size;
>> }
>> So for 4G mem guest, seabios will insert a 512M usable region beyond
>> of 4G.
>> Thus in above case max_pfn - min_low_pfn will be more than original
>> memsize.
>>
>> Fixing this issue by using memblock_phys_mem_size() to get the total
>> memsize.
>>
>
> Makes sense for me!
>
>> -static inline unsigned long long get_total_mem(void)
>> -{
>> - unsigned long long total;
>> -
>> - total = max_pfn - min_low_pfn;
>> - printk("hidave: memsize=%llu\n", memblock_phys_mem_size());
>
> This debugging line does not exist... so this patch can't be applied.
Yes, good catch, will remove the line and resend.
--
Thanks
Dave
^ permalink raw reply [flat|nested] 6+ messages in thread
* [PATCH v2] kdump x86: fix total mem size calculation for reservation
2012-03-10 3:27 ` Cong Wang
2012-03-10 4:32 ` Dave Young
@ 2012-03-10 4:56 ` Dave Young
2012-03-10 8:38 ` Cong Wang
1 sibling, 1 reply; 6+ messages in thread
From: Dave Young @ 2012-03-10 4:56 UTC (permalink / raw)
To: Cong Wang; +Cc: linux-kernel, x86, linux, vgoyal
crashkernel reservation need know the total memory size. Current get_total_mem
simply use max_pfn - min_low_pfn. It is wrong because it will including
memory holes in the middle.
Especially for kvm guest with memory > 0xe0000000, there's below in qemu code:
qemu split memory as below:
if (ram_size >= 0xe0000000 ) {
above_4g_mem_size = ram_size - 0xe0000000;
below_4g_mem_size = 0xe0000000;
} else {
below_4g_mem_size = ram_size;
}
So for 4G mem guest, seabios will insert a 512M usable region beyond of 4G.
Thus in above case max_pfn - min_low_pfn will be more than original memsize.
Fixing this issue by using memblock_phys_mem_size() to get the total memsize.
[v1 -> v2]: refresh the patch based on latest linus tree
Signed-off-by: Dave Young <dyoung@redhat.com>
---
[Ther's similar code in arm, I'm not sure whether the memblock_phys_mem_size
works with arm or not. If it works I can also update that part of code.]
arch/x86/kernel/setup.c | 11 +----------
1 file changed, 1 insertion(+), 10 deletions(-)
--- linux-2.6.orig/arch/x86/kernel/setup.c 2012-03-04 03:46:35.000000000 +0800
+++ linux-2.6/arch/x86/kernel/setup.c 2012-03-10 12:44:58.133300788 +0800
@@ -509,15 +509,6 @@ static void __init memblock_x86_reserve_
#ifdef CONFIG_KEXEC
-static inline unsigned long long get_total_mem(void)
-{
- unsigned long long total;
-
- total = max_pfn - min_low_pfn;
-
- return total << PAGE_SHIFT;
-}
-
/*
* Keep the crash kernel below this limit. On 32 bits earlier kernels
* would limit the kernel to the low 512 MiB due to mapping restrictions.
@@ -536,7 +527,7 @@ static void __init reserve_crashkernel(v
unsigned long long crash_size, crash_base;
int ret;
- total_mem = get_total_mem();
+ total_mem = memblock_phys_mem_size();
ret = parse_crashkernel(boot_command_line, total_mem,
&crash_size, &crash_base);
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH v2] kdump x86: fix total mem size calculation for reservation
2012-03-10 4:56 ` [PATCH v2] " Dave Young
@ 2012-03-10 8:38 ` Cong Wang
2012-03-10 16:06 ` Dave Young
0 siblings, 1 reply; 6+ messages in thread
From: Cong Wang @ 2012-03-10 8:38 UTC (permalink / raw)
To: Dave Young; +Cc: linux-kernel, x86, linux, vgoyal
On 03/10/2012 12:56 PM, Dave Young wrote:
> crashkernel reservation need know the total memory size. Current get_total_mem
> simply use max_pfn - min_low_pfn. It is wrong because it will including
> memory holes in the middle.
>
> Especially for kvm guest with memory> 0xe0000000, there's below in qemu code:
> qemu split memory as below:
> if (ram_size>= 0xe0000000 ) {
> above_4g_mem_size = ram_size - 0xe0000000;
> below_4g_mem_size = 0xe0000000;
> } else {
> below_4g_mem_size = ram_size;
> }
> So for 4G mem guest, seabios will insert a 512M usable region beyond of 4G.
> Thus in above case max_pfn - min_low_pfn will be more than original memsize.
>
> Fixing this issue by using memblock_phys_mem_size() to get the total memsize.
>
> [v1 -> v2]: refresh the patch based on latest linus tree
>
Looks good to my eyes,
Reviewed-by: WANG Cong <xiyou.wangcong@gmail.com>
Can you post the result of crashkernel after this patch to convince people?
Thanks.
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH v2] kdump x86: fix total mem size calculation for reservation
2012-03-10 8:38 ` Cong Wang
@ 2012-03-10 16:06 ` Dave Young
0 siblings, 0 replies; 6+ messages in thread
From: Dave Young @ 2012-03-10 16:06 UTC (permalink / raw)
To: Cong Wang; +Cc: Dave Young, linux-kernel, x86, linux, vgoyal
On Sat, Mar 10, 2012 at 4:38 PM, Cong Wang <xiyou.wangcong@gmail.com> wrote:
> On 03/10/2012 12:56 PM, Dave Young wrote:
>>
>> crashkernel reservation need know the total memory size. Current
>> get_total_mem
>> simply use max_pfn - min_low_pfn. It is wrong because it will including
>> memory holes in the middle.
>>
>> Especially for kvm guest with memory> 0xe0000000, there's below in qemu
>> code:
>> qemu split memory as below:
>> if (ram_size>= 0xe0000000 ) {
>> above_4g_mem_size = ram_size - 0xe0000000;
>> below_4g_mem_size = 0xe0000000;
>> } else {
>> below_4g_mem_size = ram_size;
>> }
>> So for 4G mem guest, seabios will insert a 512M usable region beyond of
>> 4G.
>> Thus in above case max_pfn - min_low_pfn will be more than original
>> memsize.
>>
>> Fixing this issue by using memblock_phys_mem_size() to get the total
>> memsize.
>>
>> [v1 -> v2]: refresh the patch based on latest linus tree
>>
>
> Looks good to my eyes,
>
> Reviewed-by: WANG Cong <xiyou.wangcong@gmail.com>
>
> Can you post the result of crashkernel after this patch to convince people?
Sure, for the qemu 4G vm results below:
-[ 0.000000] Reserving 128MB of memory at 768MB for crashkernel
(System RAM: 4608MB)
+[ 0.000000] Reserving 128MB of memory at 768MB for crashkernel
(System RAM: 4095MB)
>
> Thanks.
>
> --
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--
Regards
Dave
^ permalink raw reply [flat|nested] 6+ messages in thread
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2012-03-09 8:30 [PATCH] kdump x86: fix total mem size calculation for reservation Dave Young
2012-03-10 3:27 ` Cong Wang
2012-03-10 4:32 ` Dave Young
2012-03-10 4:56 ` [PATCH v2] " Dave Young
2012-03-10 8:38 ` Cong Wang
2012-03-10 16:06 ` Dave Young
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