Re: [patch 02/18] hugetlb: factor out huge_new_page

[Nishanth Aravamudan <nacc@us.ibm.com>]

On 25.04.2008 [09:10:52 +0200], Andi Kleen wrote:
> Nishanth Aravamudan wrote:
> > On 24.04.2008 [16:54:31 -0700], Nishanth Aravamudan wrote:
> >> On 23.04.2008 [11:53:04 +1000], npiggin@suse.de wrote:
> >>> Needed to avoid code duplication in follow up patches.
> >>>
> >>> This happens to fix a minor bug. When alloc_bootmem_node returns
> >>> a fallback node on a different node than passed the old code
> >>> would have put it into the free lists of the wrong node.
> >>> Now it would end up in the freelist of the correct node.
> >> This is rather frustrating. The whole point of having the __GFP_THISNODE
> >> flag is to indicate off-node allocations are *not* supported from the
> >> caller... This was all worked on quite heavily a while back.
> 
> Perhaps it was, but the result in hugetlb.c was not correct.

Huh? There is a case in current code (current hugepage sizes) that
allows __GFP_THISNODE to go off-node?

> > Oh I see. This patch refers to a bug that only is introduced by patch
> > 12/18...perhaps *that* patch should add the nid calculation in the
> > helper, if it is truly needed.
> 
> No, the bug is already there even without the bootmem patch.

Where does alloc_pages_node go off-node? It is a bug in the core VM if
it does, as we decided __GFP_THISNODE semantics with a nid specified
indicates *no* fallback should occur.

Thanks,
Nish

-- 
Nishanth Aravamudan <nacc@us.ibm.com>
IBM Linux Technology Center

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