From: Catalin Marinas <catalin.marinas@arm.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Michal Hocko <mhocko@kernel.org>,
Matthew Wilcox <willy@infradead.org>, Qian Cai <cai@lca.pw>
Subject: Re: [PATCH v2] mm: kmemleak: Use mempool allocations for kmemleak objects
Date: Wed, 31 Jul 2019 16:44:50 +0100 [thread overview]
Message-ID: <20190731154450.GB17773@arrakis.emea.arm.com> (raw)
In-Reply-To: <20190730130215.919b31c19df935cc5f1483e6@linux-foundation.org>
On Tue, Jul 30, 2019 at 01:02:15PM -0700, Andrew Morton wrote:
> On Sat, 27 Jul 2019 14:23:33 +0100 Catalin Marinas <catalin.marinas@arm.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).
>
> btw, the checkpatch warnings are valid:
>
> WARNING: usage of NR_CPUS is often wrong - consider using cpu_possible(), num_possible_cpus(), for_each_possible_cpu(), etc
> #70: FILE: mm/kmemleak.c:197:
> +static int min_object_pool = NR_CPUS * 4;
>
> WARNING: usage of NR_CPUS is often wrong - consider using cpu_possible(), num_possible_cpus(), for_each_possible_cpu(), etc
> #71: FILE: mm/kmemleak.c:198:
> +static int min_scan_area_pool = NR_CPUS * 1;
>
> There can be situations where NR_CPUS is much larger than
> num_possible_cpus(). Can we initialize these tunables within
> kmemleak_init()?
We could and, at least on arm64, cpu_possible_mask is already
initialised at that point. However, that's a totally made up number. I
think we would better go for a Kconfig option (defaulting to, say, 1024)
similar to the CONFIG_DEBUG_KMEMLEAK_EARLY_LOG_SIZE and we grow it if
people report better values in the future.
--
Catalin
next prev parent reply other threads:[~2019-07-31 15:44 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-27 13:23 [PATCH v2] mm: kmemleak: Use mempool allocations for kmemleak objects Catalin Marinas
2019-07-30 19:57 ` Andrew Morton
2019-07-30 20:22 ` Qian Cai
2019-07-30 20:39 ` Andrew Morton
2019-07-31 9:53 ` Catalin Marinas
2019-07-31 12:02 ` Qian Cai
2019-07-31 14:48 ` Catalin Marinas
2019-07-31 14:54 ` Qian Cai
2019-07-31 9:06 ` Michal Hocko
2019-07-31 9:17 ` Catalin Marinas
2019-07-30 20:02 ` Andrew Morton
2019-07-31 15:44 ` Catalin Marinas [this message]
2019-08-01 6:41 ` Michal Hocko
2019-08-03 10:48 ` Catalin Marinas
2019-07-31 9:10 ` Michal Hocko
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