Re: [PATCH v16 08/11] secretmem: add memcg accounting

[Matthew Wilcox]

On Mon, Jan 25, 2021 at 11:38:17PM +0200, Mike Rapoport wrote:
> I cannot use __GFP_ACCOUNT because cma_alloc() does not use gfp.
> Besides, kmem accounting with __GFP_ACCOUNT does not seem
> to update stats and there was an explicit request for statistics:
>  
> https://lore.kernel.org/lkml/CALo0P13aq3GsONnZrksZNU9RtfhMsZXGWhK1n=xYJWQizCd4Zw@xxxxxxxxxxxxxx/
> 
> As for (ab)using NR_SLAB_UNRECLAIMABLE_B, as it was already discussed here:
> 
> https://lore.kernel.org/lkml/20201129172625.GD557259@xxxxxxxxxx/
> 
> I think that a dedicated stats counter would be too much at the moment and
> NR_SLAB_UNRECLAIMABLE_B is the only explicit stat for unreclaimable memory.

That's not true -- Mlocked is also unreclaimable.  And doesn't this
feel more like mlocked memory than unreclaimable slab?  It's also
Unevictable, so could be counted there instead.