On 9/15/21 6:11 AM, zhenguo yao wrote:
> Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> 于2021年9月15日周三 上午11:50写道：
>>
>> On Thu, 9 Sep 2021 22:16:55 +0800 yaozhenguo <yaozhenguo1@xxxxxxxxx> wrote:
>>
>>> We can specify the number of hugepages to allocate at boot. But the
>>> hugepages is balanced in all nodes at present. In some scenarios,
>>> we only need hugepages in one node. For example: DPDK needs hugepages
>>> which are in the same node as NIC. if DPDK needs four hugepages of 1G
>>> size in node1 and system has 16 numa nodes. We must reserve 64 hugepages
>>> in kernel cmdline. But, only four hugepages are used. The others should
>>> be free after boot. If the system memory is low(for example: 64G), it will
>>> be an impossible task. So, Extending hugepages parameter to support
>>> specifying hugepages at a specific node.
>>> For example add following parameter:
>>>
>>> hugepagesz=1G hugepages=0:1,1:3
>>>
>>> It will allocate 1 hugepage in node0 and 3 hugepages in node1.
>>>
>>> ...
>>>
>>> @@ -2842,10 +2843,75 @@ static void __init gather_bootmem_prealloc(void)
>>> }
>>> }
>>>
>>> +static void __init hugetlb_hstate_alloc_pages_onenode(struct hstate *h, int nid)
>>> +{
>>> + unsigned long i;
>>> + char buf[32];
>>> +
>>> + for (i = 0; i < h->max_huge_pages_node[nid]; ++i) {
>>> + if (hstate_is_gigantic(h)) {
>>> + struct huge_bootmem_page *m;
>>> + void *addr;
>>> +
>>> + addr = memblock_alloc_try_nid_raw(
>>> + huge_page_size(h), huge_page_size(h),
>>> + 0, MEMBLOCK_ALLOC_ACCESSIBLE, nid);
>>> + if (!addr)
>>> + break;
>>> + m = addr;
>>> + BUG_ON(!IS_ALIGNED(virt_to_phys(m), huge_page_size(h)));
>>
>> We try very hard to avoid adding BUG calls. Is there any way in which
>> this code can emit a WARNing then permit the kernel to keep operating?
>>
> Maybe we can rewrite it as below:
> if (WARN(!IS_ALIGNED(virt_to_phys(m),
> huge_page_size(h)),
> "HugeTLB: page addr:%p is not aligned\n", m))
> break;
> @Mike, Do you think it's OK?
Sorry, I have not yet reviewed the latest version of this patch.
Quick thought on this question.
The required alignment passed to memblock_alloc_try_nid_raw() is
huge_page_size(h). Therefore, we know the virtual address m is
huge_page_size(h) aligned. The BUG is just checking to make sure
the physical address associated with the virtual address is aligned
the same. I really do not see how this could not be the case.
In fact, the memblock allocator finds a physical address with the
required alignment and then returns phys_to_virt(alloc).
Someone please correct me if I am wrong. Otherwise, we can drop
the BUG.
Adding Mike Rapport on Cc:
This allocation code and the associated BUG was copied from
__alloc_bootmem_huge_page(). The BUG was added 12 years ago before
the memblock allocator existed and we were using the bootmem allocator.
If there is no need for a BUG in hugetlb_hstate_alloc_pages_onenode,
there is no need for one in __alloc_bootmem_huge_page.
--
Mike Kravetz
