linux-kernel - Re: [PATCH v4] hugetlbfs: Extend the definition of hugepages parameter to support node allocation

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Date:   Wed, 15 Sep 2021 21:11:18 +0800
From:   zhenguo yao <yaozhenguo1@...il.com>
To:     Andrew Morton <akpm@...ux-foundation.org>,
        Mike Kravetz <mike.kravetz@...cle.com>
Cc:     corbet@....net, yaozhenguo@...com,
        Matthew Wilcox <willy@...radead.org>,
        linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org,
        Linux Memory Management List <linux-mm@...ck.org>
Subject: Re: [PATCH v4] hugetlbfs: Extend the definition of hugepages
 parameter to support node allocation

Andrew Morton <akpm@...ux-foundation.org> 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@...il.com> 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?
> > +                     /*
> > +                      * Put them into a private list first because mem_map
> > +                      * is not up yet
> > +                      */
> > +                     INIT_LIST_HEAD(&m->list);
> > +                     list_add(&m->list, &huge_boot_pages);
> > +                     m->hstate = h;
> > +             } else {
> > +                     struct page *page;
> > +
> > +                     gfp_t gfp_mask = htlb_alloc_mask(h) | __GFP_THISNODE;
> > +
> > +                     page = alloc_fresh_huge_page(h, gfp_mask, nid,
> > +                                     &node_states[N_MEMORY], NULL);
> > +                     if (!page)
> > +                             break;
> > +                     put_page(page); /* free it into the hugepage allocator */
> > +             }
> > +             cond_resched();
> > +     }
> > +     if (i == h->max_huge_pages_node[nid])
> > +             return;
> > +
> > +     string_get_size(huge_page_size(h), 1, STRING_UNITS_2, buf, 32);
> > +     pr_warn("HugeTLB: allocating %u of page size %s failed node%d.  Only allocated %lu hugepages.\n",
> > +             h->max_huge_pages_node[nid], buf, nid, i);
> > +     h->max_huge_pages_node[nid] = i;
> > +     h->max_huge_pages -= (h->max_huge_pages_node[nid] - i);
> > +}
> > +
>