linux-kernel - Re: apparmor: global buffers spin lock may get contended

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <dac1c2d5-367f-c8a7-c61e-c1774d98d602@canonical.com>
Date:   Sun, 30 Oct 2022 20:55:49 -0700
From:   John Johansen <john.johansen@...onical.com>
To:     Sergey Senozhatsky <senozhatsky@...omium.org>
Cc:     Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
        Peter Zijlstra <peterz@...radead.org>,
        Tomasz Figa <tfiga@...omium.org>, linux-kernel@...r.kernel.org,
        linux-security-module@...r.kernel.org
Subject: Re: apparmor: global buffers spin lock may get contended

On 10/30/22 20:52, Sergey Senozhatsky wrote:
> On (22/10/28 02:34), John Johansen wrote:
>>  From d026988196fdbda7234fb87bc3e4aea22edcbaf9 Mon Sep 17 00:00:00 2001
>> From: John Johansen <john.johansen@...onical.com>
>> Date: Tue, 25 Oct 2022 01:18:41 -0700
>> Subject: [PATCH] apparmor: cache buffers on percpu list if there is lock
>>   contention
>>
>> On a heavily loaded machine there can be lock contention on the
>> global buffers lock. Add a percpu list to cache buffers on when
>> lock contention is encountered.
>>
>> When allocating buffers attempt to use cached buffers first,
>> before taking the global buffers lock. When freeing buffers
>> try to put them back to the global list but if contention is
>> encountered, put the buffer on the percpu list.
>>
>> The length of time a buffer is held on the percpu list is dynamically
>> adjusted based on lock contention.  The amount of hold time is rapidly
>> increased and slow ramped down.
>>
>> Signed-off-by: John Johansen <john.johansen@...onical.com>
> 
> Reported-by: Sergey Senozhatsky <senozhatsky@...omium.org>

yep, thanks for catching that