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SubjectRe: 2.6.25-rc7-git2: Reported regressions from 2.6.24


On Thu, 27 Mar 2008, Christoph Lameter wrote:
>
> Slab allocations can never use GFP_HIGHMEM.

Totally irrelevant.

The page allocation path does

if (gfp_flags & __GFP_ZERO)
prep_zero_page(page, order, gfp_flags);
and that will cause a warning REGARDLESS of whether the page is a HIGHMEM
page or not.

And the fact is, passing in GFP_ZERO from the SLUB code is a bug
regardless, because it unnecessarily does the dual memset().

So here's a damn big clue:
- SLUB does its own GFP_ZERO handling
- so passing GFP_ZERO down to the page allocator is a f*cking bug
- and this has NOTHING what-so-ever to do with GFP_HIGHMEM or even
whether the warning is "valid" or not - it's a bug even if the warning
had never happened.

So stop blathering, and just admit that this was buggy. It was also
fundamentally fragile to leave GFP_ZERO around when it was known to not be
valid at that point (exactly because GFP_ZERO was handled by the caller).

Linus


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