Re: [v6 15/15] mm: debug for raw alloctor

Michal Hocko
2017-08-14T11:50:05Z

On Fri 11-08-17 12:18:24, Pasha Tatashin wrote:
> >>When CONFIG_DEBUG_VM is enabled, this patch sets all the memory that is
> >>returned by memblock_virt_alloc_try_nid_raw() to ones to ensure that no
> >>places excpect zeroed memory.
> >
> >Please fold this into the patch which introduces
> >memblock_virt_alloc_try_nid_raw.
>
> OK
>
> I am not sure CONFIG_DEBUG_VM is the
> >best config because that tends to be enabled quite often. Maybe
> >CONFIG_MEMBLOCK_DEBUG? Or even make it kernel command line parameter?
> >
>
> Initially, I did not want to make it CONFIG_MEMBLOCK_DEBUG because we really
> benefit from this debugging code when VM debug is enabled, and especially
> struct page debugging asserts which also depend on CONFIG_DEBUG_VM.
>
> However, now thinking about it, I will change it to CONFIG_MEMBLOCK_DEBUG,
> and let users decide what other debugging configs need to be enabled, as
> this is also OK.

Actually the more I think about it the more I am convinced that a kernel
boot parameter would be better because it doesn't need the kernel to be
recompiled and it is a single branch in not so hot path.
--
Michal Hocko
SUSE Labs