Messages in this thread | | | Subject | Re: [PATCH] mm: rename and document alloc_pages_exact_node | From | Michael Ellerman <> | Date | Wed, 22 Jul 2015 11:23:00 +1000 |
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On Tue, 2015-07-21 at 15:55 +0200, Vlastimil Babka wrote: > The function alloc_pages_exact_node() was introduced in 6484eb3e2a81 ("page > allocator: do not check NUMA node ID when the caller knows the node is valid") > as an optimized variant of alloc_pages_node(), that doesn't allow the node id > to be -1. Unfortunately the name of the function can easily suggest that the > allocation is restricted to the given node. In truth, the node is only > preferred, unless __GFP_THISNODE is among the gfp flags. > > The misleading name has lead to mistakes in the past, see 5265047ac301 ("mm, > thp: really limit transparent hugepage allocation to local node") and > b360edb43f8e ("mm, mempolicy: migrate_to_node should only migrate to node"). > > To prevent further mistakes, this patch renames the function to > alloc_pages_prefer_node() and documents it together with alloc_pages_node(). > > Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
> I'm CC'ing also maintainers of the callsites so they can verify that the > callsites that don't pass __GFP_THISNODE are really not intended to restrict > allocation to the given node. I went through them myself and each looked like > it's better off if it can successfully allocate on a fallback node rather > than fail. DavidR checked them also I think, but it's better if maintainers > can verify that. I'm not completely sure about all the usages in sl*b due to > multiple layers through which gfp flags are being passed.
> diff --git a/arch/powerpc/platforms/cell/ras.c b/arch/powerpc/platforms/cell/ras.c > index e865d74..646a310 100644 > --- a/arch/powerpc/platforms/cell/ras.c > +++ b/arch/powerpc/platforms/cell/ras.c > @@ -123,7 +123,7 @@ static int __init cbe_ptcal_enable_on_node(int nid, int order) > > area->nid = nid; > area->order = order; > - area->pages = alloc_pages_exact_node(area->nid, > + area->pages = alloc_pages_prefer_node(area->nid, > GFP_KERNEL|__GFP_THISNODE, > area->order);
Yeah that looks right to me.
This code enables some firmware memory calibration so I think it really does want to get memory on the specified node, or else fail.
Acked-by: Michael Ellerman <mpe@ellerman.id.au>
cheers
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