linux-kernel - Re: [PATCH v2] mm: kmemleak: Use mempool allocations for kmemleak objects

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Message-ID: <20190731090653.GD9330@dhcp22.suse.cz>
Date:   Wed, 31 Jul 2019 11:06:53 +0200
From:   Michal Hocko <mhocko@...nel.org>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     Catalin Marinas <catalin.marinas@....com>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, Matthew Wilcox <willy@...radead.org>,
        Qian Cai <cai@....pw>
Subject: Re: [PATCH v2] mm: kmemleak: Use mempool allocations for kmemleak
 objects

On Tue 30-07-19 12:57:43, Andrew Morton wrote:
> On Sat, 27 Jul 2019 14:23:33 +0100 Catalin Marinas <catalin.marinas@....com> wrote:
> 
> > Add mempool allocations for struct kmemleak_object and
> > kmemleak_scan_area as slightly more resilient than kmem_cache_alloc()
> > under memory pressure. Additionally, mask out all the gfp flags passed
> > to kmemleak other than GFP_KERNEL|GFP_ATOMIC.
> > 
> > A boot-time tuning parameter (kmemleak.mempool) is added to allow a
> > different minimum pool size (defaulting to NR_CPUS * 4).
> 
> Why would anyone ever want to alter this?  Is there some particular
> misbehaviour which this will improve?  If so, what is it?

I do agree with Andrew here. Can we simply go with no tunning for now
and only add it based on some real life reports that the auto-tuning is
not sufficient?

-- 
Michal Hocko
SUSE Labs