On 09/17/2014 02:07 AM, Michael Ellerman wrote:
>
> On Mon, 2014-09-15 at 15:33 -0500, Nathan Fontenot wrote:
>> This patch adds the ability to do memory hotplug remove in the kernel.
>>
>> Currently the hotplug add/remove of memory is handled by the drmgr
>> command. The drmgr command performs the add/remove by performing
>> some work in user-space and making requests to the kernel to handle
>> other pieces. By moving all of the work to the kernel we can do the
>> add and remove faster, and provide a common place to do memory hotplug
>> for both the PowerVM and PowerKVM environments.
>>
>> Signed-off-by: Nathan Fontenot <nf...@linux.vnet.ibm.com>
>> ---
>> arch/powerpc/platforms/pseries/hotplug-memory.c | 140
>> +++++++++++++++++++++++
>> 1 file changed, 139 insertions(+), 1 deletion(-)
>>
>> diff --git a/arch/powerpc/platforms/pseries/hotplug-memory.c
>> b/arch/powerpc/platforms/pseries/hotplug-memory.c
>> index b254773..160c424 100644
>> --- a/arch/powerpc/platforms/pseries/hotplug-memory.c
>> +++ b/arch/powerpc/platforms/pseries/hotplug-memory.c
>> @@ -193,7 +193,137 @@ static int pseries_remove_mem_node(struct device_node
>> *np)
>> pseries_remove_memblock(base, lmb_size);
>> return 0;
>> }
>> +
>> +static int lmb_is_removable(struct of_drconf_cell *lmb)
>> +{
>
> Do we not already have something like this?
No. Perhaps your thinking of the code in drivers/base/memory.c that
handles the sysfs removable file. That code just calls the same
is_mem_section_removable() routine.
>
>> + int i, scns_per_block;
>> + int rc = 1;
>
> I can see this makes the &= work below.
>
> But what if block_sz / MIN_MEMORY_BLOCK_SIZE = 0 ?
If that happens, something else is really wrong. Most
likely a malformed device tree.
For pseries MIN_MEMORY_BLOCK_SIZE is defined to be the smallest
LMB size we suppport, 16MB.
I can add a pr_warn() statement here and bail if that happens.
>
>> + unsigned long pfn, block_sz;
>> + u64 phys_addr;
>> +
>> + phys_addr = be64_to_cpu(lmb->base_addr);
>> + block_sz = memory_block_size_bytes();
>> + scns_per_block = block_sz / MIN_MEMORY_BLOCK_SIZE;
>> +
>> + for (i = 0; i < scns_per_block; i++) {
>> + pfn = PFN_DOWN(phys_addr);
>> + if (!pfn_present(pfn))
>> + continue;
>> +
>> + rc &= is_mem_section_removable(pfn, PAGES_PER_SECTION);
>> + phys_addr += MIN_MEMORY_BLOCK_SIZE;
>> + }
>> +
>> + return rc;
>> +}
>
>> +static int dlpar_memory_remove(struct pseries_hp_errorlog *hp_elog)
>> +{
>
> ...
>
>> +}
>
> Most of the same comments as for add.
>
ok, I'll go through them and apply them to the remove code.
Thanks for the review.
-Nathan
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