linux-kernel - Re: [PATCH v2] ring-buffer: Prevent inconsistent operation on cpu_buffer->resize

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]

Date:   Mon, 10 Apr 2023 01:35:11 +0000
From:   Tze-nan Wu (吳澤南) 
        <Tze-nan.Wu@...iatek.com>
To:     "mhiramat@...nel.org" <mhiramat@...nel.org>,
        "rostedt@...dmis.org" <rostedt@...dmis.org>,
        "bagasdotme@...il.com" <bagasdotme@...il.com>
CC:     "linux-mediatek@...ts.infradead.org" 
        <linux-mediatek@...ts.infradead.org>,
        "linux-trace-kernel@...r.kernel.org" 
        <linux-trace-kernel@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Cheng-Jui Wang (王正睿) 
        <Cheng-Jui.Wang@...iatek.com>,
        wsd_upstream <wsd_upstream@...iatek.com>,
        Bobule Chang (張弘義) 
        <bobule.chang@...iatek.com>,
        "stable@...r.kernel.org" <stable@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "angelogioacchino.delregno@...labora.com" 
        <angelogioacchino.delregno@...labora.com>
Subject: Re: [PATCH v2] ring-buffer: Prevent inconsistent operation on
 cpu_buffer->resize_disabled

Hi Bagas,

On Sun, 2023-04-09 at 19:30 +0700, Bagas Sanjaya wrote:
> 
> On 4/9/23 09:46, Tze-nan Wu wrote:
> > This issue can be reproduced by "echo 0 > trace" and hotplug cpu at
> > the
> > same time. After reproducing success, we can find out
> > buffer_size_kb
> > will not be functional anymore.
> > 
> 
> Do you mean disabling tracing while hotplugging CPU? Or disabling
> both
> tracing and hotplug CPU?
> 
  I mean disabling tracing while hotplugging CPU, sorry for the
confusion here.

> > This patch uses cpus_read_lock() to prevent cpu_online_mask being
> > changed
> > between two different "for_each_online_buffer_cpu".
> > 
> 
> "Use cpu_read_lock() to prevent ..."
> 
  Thanks for the suggestion 

> > Changes in v2:
> >   Use cpus_read_lock() instead of copying cpu_online_mask at the
> > entry of
> >   function
> > 
> 
  Since I change to fix the issue by using cpus_read_lock(), we don't
need a copy of cpu_online_mask anymore, hence the two warnings will not
meet in the v2 patch.

> To resolve kernel test robot warnings ([1] and [2])? Or have they
> been fixed?
> 
> [1]: 
> https://lore.kernel.org/stable/202304081615.eiaqpbV8-lkp@intel.com/
> [2]: 
> https://lore.kernel.org/stable/202304082051.Dp50upfS-lkp@intel.com/
> 
> Thanks.
> 
> --
> An old man doll... just what I always wanted! - Clara
>