> return 0;
> @@ -1505,7 +1505,7 @@ int __meminit vmemmap_populate(unsigned long start,
> unsigned long end, int node,
> int err;
>
> if (end - start < PAGES_PER_SECTION * sizeof(struct page))
> - err = vmemmap_populate_basepages(start, end, node);
> + err = vmemmap_populate_basepages(start, end, node, NULL);
> else if (boot_cpu_has(X86_FEATURE_PSE))
> err = vmemmap_populate_hugepages(start, end, node, altmap);
> else if (altmap) {
It's somewhat weird that we don't allocate basepages from altmap on x86
(both for sub-sections and without PSE). I wonder if we can simply
unlock that with your change. Especially, also handle the
!X86_FEATURE_PSE case below properly with an altmap.
a) all hw with PMEM has PSE - except special QEMU setups, so nobody
cared to implement. For the sub-section special case, nobody cared about
a handfull of memmap not ending up on the altmap. (but it's still wasted
system memory IIRC).
b) the pagetable overhead for small pages is not-neglectable and might
result in similar issues as solved by the switch to altmap on very huge
PMEM (with small amount of system RAM).
I guess it is due to a).
[...]
>
> -pte_t * __meminit vmemmap_pte_populate(pmd_t *pmd, unsigned long addr, int
> node)
> +pte_t * __meminit vmemmap_pte_populate(pmd_t *pmd, unsigned long addr, int
> node,
> + struct vmem_altmap *altmap)
> {
> pte_t *pte = pte_offset_kernel(pmd, addr);
> if (pte_none(*pte)) {
> pte_t entry;
> - void *p = vmemmap_alloc_block_buf(PAGE_SIZE, node);
> + void *p;
> +
> + if (altmap)
> + p = altmap_alloc_block_buf(PAGE_SIZE, altmap);
> + else
> + p = vmemmap_alloc_block_buf(PAGE_SIZE, node);
> if (!p)
> return NULL;
I was wondering if
if (altmap)
p = altmap_alloc_block_buf(PAGE_SIZE, altmap);
if (!p)
p = vmemmap_alloc_block_buf(PAGE_SIZE, node);
if (!p)
return NULL
Would make sense. But I guess this isn't really relevant in practice,
because the altmap is usually sized properly.
In general, LGTM.
--
Thanks,
David / dhildenb
