Re: [tip:x86/mm] x86/mm/numa: Fix 32-bit kernel NUMA boot

[Lans Zhang]

On 12/20/2013 12:44 AM, Yinghai Lu wrote:
> On Thu, Dec 19, 2013 at 7:42 AM, tip-bot for Lans Zhang
> <tipbot@xxxxxxxxx>  wrote:
> > Commit-ID:  f3d815cb854b2f6262ade56a4d91a1ed3f1e50c4
> > Gitweb:     http://git.kernel.org/tip/f3d815cb854b2f6262ade56a4d91a1ed3f1e50c4
> > Author:     Lans Zhang<jia.zhang@xxxxxxxxxxxxx>
> > AuthorDate: Fri, 6 Dec 2013 12:18:30 +0800
> > Committer:  Ingo Molnar<mingo@xxxxxxxxxx>
> > CommitDate: Thu, 19 Dec 2013 13:58:36 +0100
> >
> > x86/mm/numa: Fix 32-bit kernel NUMA boot
> >
> > When booting a 32-bit x86 kernel on a NUMA machine, node data
> > cannot be allocated from local node if the account of memory for
> > node 0 covers the low memory space entirely:
> >
> >    [    0.000000] Initmem setup node 0 [mem 0x00000000-0x83fffffff]
> >    [    0.000000]   NODE_DATA [mem 0x367ed000-0x367edfff]
> >    [    0.000000] Initmem setup node 1 [mem 0x840000000-0xfffffffff]
> >    [    0.000000] Cannot find 4096 bytes in node 1
> >    [    0.000000] 64664MB HIGHMEM available.
> >    [    0.000000] 871MB LOWMEM available.
> >
> > To fix this issue, node data is allowed to be allocated from
> > other nodes if the memory of local node is still not mapped. The
> > expected result looks like this:
> >
> >    [    0.000000] Initmem setup node 0 [mem 0x00000000-0x83fffffff]
> >    [    0.000000]   NODE_DATA [mem 0x367ed000-0x367edfff]
> >    [    0.000000] Initmem setup node 1 [mem 0x840000000-0xfffffffff]
> >    [    0.000000]   NODE_DATA [mem 0x367ec000-0x367ecfff]
> >    [    0.000000]     NODE_DATA(1) on node 0
> >    [    0.000000] 64664MB HIGHMEM available.
> >    [    0.000000] 871MB LOWMEM available.
> >
> > Signed-off-by: Lans Zhang<jia.zhang@xxxxxxxxxxxxx>
> > Cc:<andi@xxxxxxxxxxxxxx>
> > Cc: Yinghai Lu<yinghai@xxxxxxxxxx>
> > Link: http://lkml.kernel.org/r/1386303510-18574-1-git-send-email-jia.zhang@xxxxxxxxxxxxx
> > Signed-off-by: Ingo Molnar<mingo@xxxxxxxxxx>
> > ---
> >   arch/x86/mm/numa.c | 10 +++++++---
> >   1 file changed, 7 insertions(+), 3 deletions(-)
> >
> > diff --git a/arch/x86/mm/numa.c b/arch/x86/mm/numa.c
> > index 24aec58..c85da7b 100644
> > --- a/arch/x86/mm/numa.c
> > +++ b/arch/x86/mm/numa.c
> > @@ -211,9 +211,13 @@ static void __init setup_node_data(int nid, u64 start, u64 end)
> >           */
> >          nd_pa = memblock_alloc_nid(nd_size, SMP_CACHE_BYTES, nid);
> >          if (!nd_pa) {
> > -               pr_err("Cannot find %zu bytes in node %d\n",
> > -                      nd_size, nid);
> > -               return;
> > +               nd_pa = __memblock_alloc_base(nd_size, SMP_CACHE_BYTES,
> > +                                             MEMBLOCK_ALLOC_ACCESSIBLE);
> > +               if (!nd_pa) {
> > +                       pr_err("Cannot find %zu bytes in node %d\n",
> > +                              nd_size, nid);
> > +                       return;
> > +               }
> >          }
> >          nd = __va(nd_pa);
>
> Can you just use memblock_alloc_try_nid instead memblock_alloc_nid?

But memblock_alloc_base() inside memblock_alloc_try_nid() may cause kernel panic
if __memblock_alloc_base() inside it fails. In current stage, it is allowed if
node data fails to be allocated.

Thanks,
lz

> Thanks
>
> Yinghai

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