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SubjectRe: [RFC][PATCH v2 11/21] kvm: allocate page table pages from DRAM
On Tue, Jan 01, 2019 at 02:53:07PM +0530, Aneesh Kumar K.V wrote:
> Fengguang Wu <fengguang.wu@intel.com> writes:
>
> > From: Yao Yuan <yuan.yao@intel.com>
> >
> > Signed-off-by: Yao Yuan <yuan.yao@intel.com>
> > Signed-off-by: Fengguang Wu <fengguang.wu@intel.com>
> > ---
> > arch/x86/kvm/mmu.c | 12 +++++++++++-
> > 1 file changed, 11 insertions(+), 1 deletion(-)
> >
> > --- linux.orig/arch/x86/kvm/mmu.c 2018-12-26 20:54:48.846720344 +0800
> > +++ linux/arch/x86/kvm/mmu.c 2018-12-26 20:54:48.842719614 +0800
> > @@ -950,6 +950,16 @@ static void mmu_free_memory_cache(struct
> > kmem_cache_free(cache, mc->objects[--mc->nobjs]);
> > }
> >
> > +static unsigned long __get_dram_free_pages(gfp_t gfp_mask)
> > +{
> > + struct page *page;
> > +
> > + page = __alloc_pages(GFP_KERNEL_ACCOUNT, 0, numa_node_id());
> > + if (!page)
> > + return 0;
> > + return (unsigned long) page_address(page);
> > +}
> > +
>
> May be it is explained in other patches. What is preventing the
> allocation from pmem here? Is it that we are not using the memory
> policy prefered node id and hence the zone list we built won't have the
> PMEM node?

That because the PMEM nodes are memory-only node in the patchset,
so numa_node_id() will always return the node id from DRAM nodes.

About the zone list, yes in patch 10/21 we build the PMEM nodes to
seperate zonelist, so DRAM nodes will not fall back to PMEM nodes.

>
> > static int mmu_topup_memory_cache_page(struct kvm_mmu_memory_cache *cache,
> > int min)
> > {
> > @@ -958,7 +968,7 @@ static int mmu_topup_memory_cache_page(s
> > if (cache->nobjs >= min)
> > return 0;
> > while (cache->nobjs < ARRAY_SIZE(cache->objects)) {
> > - page = (void *)__get_free_page(GFP_KERNEL_ACCOUNT);
> > + page = (void *)__get_dram_free_pages(GFP_KERNEL_ACCOUNT);
> > if (!page)
> > return cache->nobjs >= min ? 0 : -ENOMEM;
> > cache->objects[cache->nobjs++] = page;
>
> -aneesh
>

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