Re: Oops in a driver while using SLUB as a SLAB allocator

[Hugh Dickins]

On Thu, 21 Jun 2007, Christoph Lameter wrote:
> On Thu, 21 Jun 2007, Hugh Dickins wrote:
> 
> > Seems a little odd that it's gone throughout 2.6.22-rc unnoticed
> > until now - nobody else trying SLUB on ARM or PA-RISC yet perhaps.
> 
> The impact is only on a subset of ARM machines.
> 
> PA_RISC? It looks like they run their own flushing function for byte 
> ranges called flush_kernel_dache_range. That does not use the page struct.

PA-RISC does have a function of that name, and I'm guessing that
you came across it in looking at the PA-RISC dma_map_single.

But PA-RISC also has a function called flush_dcache_page, which uses
page_mapping and expects a struct address_space * from it.  If that
can ever be get applied to a SLOB page (which is not so clear as in
the ARM case, but cannot easily be ruled out completely), we're
in trouble without a PageSlab test within page_mapping.

Hugh
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