linux-kernel - Re: [PATCH v2 10/23] percpu: change the number of pages marked in the first

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Date:   Tue, 25 Jul 2017 14:27:24 -0400
From:   Josef Bacik <josef@...icpanda.com>
To:     Dennis Zhou <dennisz@...com>
Cc:     Tejun Heo <tj@...nel.org>, Christoph Lameter <cl@...ux.com>,
        Josef Bacik <josef@...icpanda.com>,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        kernel-team@...com, Dennis Zhou <dennisszhou@...il.com>
Subject: Re: [PATCH v2 10/23] percpu: change the number of pages marked in
 the first_chunk pop bitmap

On Mon, Jul 24, 2017 at 07:02:07PM -0400, Dennis Zhou wrote:
> From: "Dennis Zhou (Facebook)" <dennisszhou@...il.com>
> 
> The populated bitmap represents the state of the pages the chunk serves.
> Prior, the bitmap was marked completely used as the first chunk was
> allocated and immutable. This is misleading because the first chunk may
> not be completely filled. Additionally, with moving the base_addr up in
> the previous patch, the population check no longer corresponds to what
> was being checked.
> 
> This patch modifies the population map to be only the number of pages
> the region serves and to make what it was checking correspond correctly
> again. The change is to remove any misunderstanding between the size of
> the populated bitmap and the actual size of it. The work function page
> iterators now use nr_pages for the check rather than pcpu_unit_pages
> because nr_populated is now chunk specific. Without this, the work
> function would try to populate the remainder of these chunks despite it
> not serving any more than nr_pages when nr_pages is set less than
> pcpu_unit_pages.
> 
> Signed-off-by: Dennis Zhou <dennisszhou@...il.com>

Reviewed-by: Josef Bacik <jbacik@...com>

Thanks,

Josef