Re: [PATCH 2/3] mm, page_alloc: pull out side effects from free_pages_check

[Vlastimil Babka]

On 04/27/2016 02:41 PM, Mel Gorman wrote:
> On Wed, Apr 27, 2016 at 02:01:15PM +0200, Vlastimil Babka wrote:
> > Check without side-effects should be easier to maintain. It also removes the
> > duplicated cpupid and flags reset done in !DEBUG_VM variant of both
> > free_pcp_prepare() and then bulkfree_pcp_prepare(). Finally, it enables
> > the next patch.
>
> Hmm, now the cpuid and flags reset is done in multiple places. While
> this is potentially faster, it goes against the comment "I don't like the
> duplicated code in free_pcp_prepare() from maintenance perspective".

After patch 3/3 it's done only in free_pages_prepare() which I think is 
not that bad, even though it's two places there. Tail pages are already 
special in that function. And I thought that the fact it was done twice 
in !DEBUG_VM free path was actually not intentional, but a consequence 
of the side-effect being unexpected. But it's close to bike-shedding 
area so I don't insist. Anyway, overal I like the code after patch 3/3 
better than before 2/3.