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

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Message-ID: <25fb28e4-f3fe-4236-7d76-3aed04d84956@mellanox.com>
Date:   Thu, 5 Dec 2019 16:16:22 +0000
From:   Noam Stolero <noams@...lanox.com>
To:     Catalin Marinas <catalin.marinas@....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>,
        Moshe Shemesh <moshe@...lanox.com>
Subject: Re: [PATCH v3 0/3] mm: kmemleak: Use a memory pool for kmemleak
 object allocations

On 12/3/2019 6:08 PM, Catalin Marinas wrote:
> 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.

I've tested this commit, as well as 5.4.0-rc6 and 5.4.0 GA versions. We 
don't see the issue I've mentioned.

Thank you for the quick response and the assistance.