On 04/03/2018 03:21 PM, Hari Bathini wrote:
>
>
> On Monday 02 April 2018 12:00 PM, Mahesh J Salgaonkar wrote:
>> From: Mahesh Salgaonkar <mah...@linux.vnet.ibm.com>
>>
>> The second kernel, during early boot after the crash, reserves rest of
>> the memory above boot memory size to make sure it does not touch any
>> of the
>> dump memory area. It uses memblock_reserve() that reserves the specified
>> memory region irrespective of memory holes present within that region.
>> There are chances where previous kernel would have hot removed some of
>> its memory leaving memory holes behind. In such cases fadump kernel
>> reports
>> incorrect number of reserved pages through arch_reserved_kernel_pages()
>> hook causing kernel to hang or panic.
>>
>> Fix this by excluding memory holes while reserving rest of the memory
>> above boot memory size during second kernel boot after crash.
>>
>> Signed-off-by: Mahesh Salgaonkar <mah...@linux.vnet.ibm.com>
>> ---
>> arch/powerpc/kernel/fadump.c | 17 ++++++++++++++++-
>> 1 file changed, 16 insertions(+), 1 deletion(-)
>>
>> diff --git a/arch/powerpc/kernel/fadump.c b/arch/powerpc/kernel/fadump.c
>> index 011f1aa7abab..a497e9fb93fe 100644
>> --- a/arch/powerpc/kernel/fadump.c
>> +++ b/arch/powerpc/kernel/fadump.c
>> @@ -433,6 +433,21 @@ static inline unsigned long
>> get_fadump_metadata_base(
>> return be64_to_cpu(fdm->metadata_region.source_address);
>> }
>>
>> +static void fadump_memblock_reserve(unsigned long base, unsigned long
>> size)
>> +{
>> + struct memblock_region *reg;
>> + unsigned long start, end;
>> +
>> + for_each_memblock(memory, reg) {
>> + start = max(base, (unsigned long)reg->base);
>> + end = reg->base + reg->size;
>> + end = min(base + size, end);
>> +
>> + if (start < end)
>> + memblock_reserve(start, end - start);
>> + }
>> +}
>> +
>> int __init fadump_reserve_mem(void)
>> {
>> unsigned long base, size, memory_boundary;
>> @@ -487,7 +502,7 @@ int __init fadump_reserve_mem(void)
>> */
>> base = fw_dump.boot_memory_size;
>> size = memory_boundary - base;
>> - memblock_reserve(base, size);
>> + fadump_memblock_reserve(base, size);
>> printk(KERN_INFO "Reserved %ldMB of memory at %ldMB "
>
> Mahesh, you may want to change this print as well as it would be
> misleading in case of
> holes in the memory.
Yeah, may be we can just move that printk also inside
fadump_memblock_reserve().
Thanks,
-Mahesh.
>
> Thanks
> Hari
>
>> "for saving crash dump\n",
>> (unsigned long)(size >> 20),
>>
>
