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

[Eric Dumazet]

On 04/10/2018 05:53 AM, Matthew Wilcox wrote:
> From: Matthew Wilcox <mawilcox@xxxxxxxxxxxxx>
> 
> __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.
> 
> Fixes: d07dbea46405 ("Slab allocators: support __GFP_ZERO in all allocators")
> Signed-off-by: Matthew Wilcox <mawilcox@xxxxxxxxxxxxx>
> Cc: stable@xxxxxxxxxxxxxxx


Since there are probably no bug to fix, what about adding the extra check
only for some DEBUG option ?

How many caches are still using ctor these days ?