linux-kernel - Re: [PATCH v3 0/3] mm: kmemleak: Use a memory pool for kmemleak object allocations

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Message-Id: <20190812140730.71dd7f35d568b4d8530f8908@linux-foundation.org>
Date:   Mon, 12 Aug 2019 14:07:30 -0700
From:   Andrew Morton <akpm@...ux-foundation.org>
To:     Catalin Marinas <catalin.marinas@....com>
Cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        Michal Hocko <mhocko@...nel.org>,
        Matthew Wilcox <willy@...radead.org>, Qian Cai <cai@....pw>
Subject: Re: [PATCH v3 0/3] mm: kmemleak: Use a memory pool for kmemleak
 object allocations

On Mon, 12 Aug 2019 17:06:39 +0100 Catalin Marinas <catalin.marinas@....com> wrote:

> Following the discussions on v2 of this patch(set) [1], this series
> takes slightly different approach:
> 
> - it implements its own simple memory pool that does not rely on the
>   slab allocator
> 
> - drops the early log buffer logic entirely since it can now allocate
>   metadata from the memory pool directly before kmemleak is fully
>   initialised
> 
> - CONFIG_DEBUG_KMEMLEAK_EARLY_LOG_SIZE option is renamed to
>   CONFIG_DEBUG_KMEMLEAK_MEM_POOL_SIZE
> 
> - moves the kmemleak_init() call earlier (mm_init())
> 
> - to avoid a separate memory pool for struct scan_area, it makes the
>   tool robust when such allocations fail as scan areas are rather an
>   optimisation
> 
> [1] http://lkml.kernel.org/r/20190727132334.9184-1-catalin.marinas@arm.com

Using the term "memory pool" is a little unfortunate, but better than
using "mempool"!

The changelog doesn't answer the very first question: why not use
mempools.  Please send along a paragraph which explains this decision.