Re: [PATCH 1/2] slab: __GFP_ZERO is incompatible with a constructor

[Christopher Lameter]

On Tue, 10 Apr 2018, Christopher Lameter wrote:

> On Tue, 10 Apr 2018, Matthew Wilcox wrote:
>
> > __GFP_ZERO requests that the object be initialised to all-zeroes,
> > while the purpose of a constructor is to initialise an object to a
> > particular pattern.  We cannot do both.  Add a warning to catch any
> > users who mistakenly pass a __GFP_ZERO flag when allocating a slab with
> > a constructor.
>
> Can we move this check out of the critical paths and check for
> a ctor and GFP_ZERO when calling the page allocator? F.e. in
> allocate_slab()?

The ctor's are run at that point from setup_object() so it makes sense.