On 2023/3/3 11:01, Baoquan He wrote:
> On 03/02/23 at 11:32am, Leizhen (ThunderTown) wrote:
> ......
>>> @@ -166,31 +169,51 @@ static void __init reserve_crashkernel(void)
>>> /* User specifies base address explicitly. */
>>> if (crash_base) {
>>> fixed_base = true;
>>> + search_base = crash_base;
>>> crash_max = crash_base + crash_size;
>>> }
>>>
>>> retry:
>>> crash_base = memblock_phys_alloc_range(crash_size, CRASH_ALIGN,
>>> - crash_base, crash_max);
>>> + search_base, crash_max);
>>> if (!crash_base) {
>>> /*
>>> - * If the first attempt was for low memory, fall back to
>>> - * high memory, the minimum required low memory will be
>>> - * reserved later.
>>> + * For crashkernel=size[KMG]@offset[KMG], print out failure
>>> + * message if can't reserve the specified region.
>>> */
>>> - if (!fixed_base && (crash_max == CRASH_ADDR_LOW_MAX)) {
>>> + if (fixed_base) {
>>> + pr_info("crashkernel reservation failed - memory is in use.\n");
>>
>> How about changing pr_info to pr_warn?
>>
>>> + return;
>>> + }
>>> +
>>> + /*
>>> + * For crashkernel=size[KMG], if the first attempt was for
>>> + * low memory, fall back to high memory, the minimum required
>>> + * low memory will be reserved later.
>>> + */
>>> + if (!high && crash_max == CRASH_ADDR_LOW_MAX) {
>>> crash_max = CRASH_ADDR_HIGH_MAX;
>>> + search_base = CRASH_ADDR_LOW_MAX;
>>> crash_low_size = DEFAULT_CRASH_KERNEL_LOW_SIZE;
>>> goto retry;
>>> }
>>>
>>> + /*
>>> + * For crashkernel=size[KMG],high, if the first attempt was
>>> + * for high memory, fall back to low memory.
>>> + */
>>> + if (high && crash_max == CRASH_ADDR_HIGH_MAX) {
>>
>> Adding unlikely to indicate that it is rare would be better.
>>
>> if (unlikely(high && crash_max == CRASH_ADDR_HIGH_MAX))
>
> Rethink about this and checked code in kernel, seems likely|unlikely are
> mostly used in highly frequent execution branch optimize code path, while
> crashkernel resevatoin is one time execution during boot, we may not
> need to bother to add unlikely. What do you think?
OK.
>
>
>>
>>> + crash_max = CRASH_ADDR_LOW_MAX;
>>> + search_base = 0;
>>> + goto retry;
>>> + }
>>> pr_warn("cannot allocate crashkernel (size:0x%llx)\n",
>>> crash_size);
>>> return;
>>> }
>>>
>>> - if ((crash_base > CRASH_ADDR_LOW_MAX - crash_low_size) &&
>>> - crash_low_size && reserve_crashkernel_low(crash_low_size)) {
>>> + if ((crash_base >= CRASH_ADDR_LOW_MAX) && crash_low_size &&
>>> + reserve_crashkernel_low(crash_low_size)) {
>>> memblock_phys_free(crash_base, crash_size);
>>> return;
>>> }
>>>
>>
>> --
>> Regards,
>> Zhen Lei
>>
>
> .
>
--
Regards,
Zhen Lei
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