Re: [PATCH] mm: drop VM_BUG_ON from __get_free_pages

[Vlastimil Babka]

On 06/27/2018 09:34 AM, Michal Hocko wrote:
> On Tue 26-06-18 10:04:16, Andrew Morton wrote:
> 
> And as I've argued before the code would be wrong regardless. We would
> leak the memory or worse touch somebody's else kmap without knowing
> that.  So we have a choice between a mem leak, data corruption k or a
> silent fixup. I would prefer the last option. And blowing up on a BUG
> is not much better on something that is easily fixable. I am not really
> convinced that & ~__GFP_HIGHMEM is something to lose sleep over.

Maybe put the fixup into a "#ifdef CONFIG_HIGHMEM" block and then modern
systems won't care? In that case it could even be if (WARN_ON_ONCE(...))
so future cases with wrong expectations would become known.

Vlastimil