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

From: Noam Stolero <noams@mellanox.com>
To: Catalin Marinas <catalin.marinas@arm.com>
Cc: "linux-mm@kvack.org" <linux-mm@kvack.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Michal Hocko <mhocko@kernel.org>,
	Matthew Wilcox <willy@infradead.org>, Qian Cai <cai@lca.pw>,
	Tal Gilboa <talgi@mellanox.com>,
	Tariq Toukan <tariqt@mellanox.com>,
	Saeed Mahameed <saeedm@mellanox.com>,
	Amir Ancel <amira@mellanox.com>, Matan Nir <matann@mellanox.com>,
	Bar Tuaf <bartu@mellanox.com>,
	"brouer@redhat.com" <brouer@redhat.com>,
	"edumazet@google.com" <edumazet@google.com>,
	"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
	Moshe Shemesh <moshe@mellanox.com>
Subject: Re: [PATCH v3 0/3] mm: kmemleak: Use a memory pool for kmemleak object allocations
Date: Thu, 5 Dec 2019 16:16:22 +0000	[thread overview]
Message-ID: <25fb28e4-f3fe-4236-7d76-3aed04d84956@mellanox.com> (raw)
In-Reply-To: <20191203160806.GB23522@arrakis.emea.arm.com>

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.