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

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Date:   Tue, 3 Dec 2019 16:08:06 +0000
From:   Catalin Marinas <catalin.marinas@....com>
To:     Noam Stolero <noams@...lanox.com>
Cc:     "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Michal Hocko <mhocko@...nel.org>,
        Matthew Wilcox <willy@...radead.org>, Qian Cai <cai@....pw>,
        Tal Gilboa <talgi@...lanox.com>,
        Tariq Toukan <tariqt@...lanox.com>,
        Saeed Mahameed <saeedm@...lanox.com>,
        Amir Ancel <amira@...lanox.com>,
        Matan Nir <matann@...lanox.com>, Bar Tuaf <bartu@...lanox.com>,
        "brouer@...hat.com" <brouer@...hat.com>,
        "edumazet@...gle.com" <edumazet@...gle.com>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: Re: [PATCH v3 0/3] mm: kmemleak: Use a memory pool for kmemleak
 object allocations

On Tue, Dec 03, 2019 at 03:51:50PM +0000, Noam Stolero wrote:
> On 8/12/2019 7:06 PM, Catalin Marinas 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
> > 
> >     Catalin Marinas (3):
> >       mm: kmemleak: Make the tool tolerant to struct scan_area allocation
> >         failures
> >       mm: kmemleak: Simple memory allocation pool for kmemleak objects
> >       mm: kmemleak: Use the memory pool for early allocations
> > 
> >      init/main.c       |   2 +-
> >      lib/Kconfig.debug |  11 +-
> >      mm/kmemleak.c     | 325 ++++++++++++----------------------------------
> >      3 files changed, 91 insertions(+), 247 deletions(-)
> 
> We observe severe degradation in our network performance affecting all
> of our NICs. The degradation is directly linked to this patch.
> 
> What we run:
> Simple Iperf TCP loopback with 8 streams on ConnectX5-100GbE.
> Since it's a loopback test, traffic goes from the socket through the IP
> stack and back to the socket, without going through the NIC driver.

Something similar was reported before. Can you try commit 2abd839aa7e6
("kmemleak: Do not corrupt the object_list during clean-up") and see if
it fixes the problem for you? It was merged in 5.4-rc4.

-- 
Catalin