linux-kernel - Re: [PATCH v2 08/23] percpu: modify base

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Date:   Tue, 25 Jul 2017 14:24:02 -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 08/23] percpu: modify base_addr to be region specific

On Mon, Jul 24, 2017 at 07:02:05PM -0400, Dennis Zhou wrote:
> From: "Dennis Zhou (Facebook)" <dennisszhou@...il.com>
> 
> Originally, the first chunk was served by one or two chunks, each
> given a region they are responsible for. Despite this, the arithmetic
> was based off of the true base_addr of the chunk making it be overly
> inclusive.
> 
> This patch moves the base_addr of chunks that are responsible for the
> first chunk. The base_addr must remain page aligned to keep the
> address alignment correct, so it is the beginning of the region served
> page aligned down. start_offset holds where the region served begins
> from this new base_addr.
> 
> The corresponding percpu address checks are modified to be more specific
> as a result. The first chunk considers only the dynamic region and both
> first chunk and reserved chunk checks ignore the static region. The
> static region addresses should never be passed into the allocator. There
> is no impact here besides distinguishing the first chunk and making the
> checks specific.
> 
> The percpu pointer to physical address is left intact as addresses are
> not given out in the non-allocated portion of percpu memory.
> 
> nr_pages is added to pcpu_chunk to keep track of the size of the entire
> region served containing both start_offset and end_offset. This variable
> will be used to manage the bitmap allocator.
> 
> Signed-off-by: Dennis Zhou <dennisszhou@...il.com>

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

Thanks,

Josef