Messages in this thread | | | Date | Fri, 20 Apr 2012 21:14:18 +0200 | From | Sam Ravnborg <> | Subject | Re: Weirdness in __alloc_bootmem_node_high |
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On Fri, Apr 20, 2012 at 11:29:07AM -0700, Tejun Heo wrote: > On Tue, Apr 17, 2012 at 05:55:02PM +0200, Michal Hocko wrote: > > Hi, > > I just come across the following condition in __alloc_bootmem_node_high > > which I have hard times to understand. I guess it is a bug and we need > > something like the following. But, to be honest, I have no idea why we > > care about those 128MB above MAX_DMA32_PFN. > > --- > > mm/bootmem.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/mm/bootmem.c b/mm/bootmem.c > > index 0131170..5adb072 100644 > > --- a/mm/bootmem.c > > +++ b/mm/bootmem.c > > @@ -737,7 +737,7 @@ void * __init __alloc_bootmem_node_high(pg_data_t *pgdat, unsigned long size, > > /* update goal according ...MAX_DMA32_PFN */ > > end_pfn = pgdat->node_start_pfn + pgdat->node_spanned_pages; > > > > - if (end_pfn > MAX_DMA32_PFN + (128 >> (20 - PAGE_SHIFT)) && > > + if (end_pfn > MAX_DMA32_PFN + (128 << (20 - PAGE_SHIFT)) && > > (goal >> PAGE_SHIFT) < MAX_DMA32_PFN) { > > void *ptr; > > unsigned long new_goal; > > Regardless of x86 not using it, this is a bug fix and this code path > seems to be used by mips at least.
I took a quick look at this. __alloc_bootmem_node_high() is used in mm/sparse.c - but only if SPARSEMEM_VMEMMAP is enabled.
mips has this:
config ARCH_SPARSEMEM_ENABLE bool select SPARSEMEM_STATIC
So SPARSEMEM_VMEMMAP is not enabled.
__alloc_bootmem_node_high() is used in mm/sparse-vmemmap.c which also depends on CONFIG_SPARSEMEM_VMEMMAP.
So I really do not see the logic in __alloc_bootmem_node_high() being used anymore and it can be replaced by __alloc_bootmem_node()
Sam
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