Re: [Powertop] A series of patches towards limiting memory corruption and foot print
Kalowsky, Daniel <daniel.kalowsky at intel.com>
| Newsgroups | dev.linux.lists.powertop |
|---|---|
| Message-ID | <4628F0C61321354285DF2950999754456DF935BE@ORSMSX114.amr.corp.intel.com> |
Sorry about a second post, looks like email stripped the attachements. Second attempt here. From: PowerTop [mailto:powertop-bounces(a)lists.01.org] On Behalf Of Kalowsky, Daniel Sent: Tuesday, April 29, 2014 5:15 PM To: powertop(a)lists.01.org Subject: [Powertop] A series of patches towards limiting memory corruption and foot print Hi Powertop, I've been working with the interactive mode and have run into cases where powertop will crash due to a series of memory corruptions. The following series of patches have helped to reduce the frequency of the issue, although not completely solved it. The issues arise much faster on platforms where there are constrained amounts of RAM to work within. Patch 1 - When shutting down the interactive display, the display bits of memory is not correctly released. This patch provides a method for correctly doing so. Patch 2 - Solving a documented memory leak with a non-elegant solution. The path either adds the bundle to the stack, or it forgets about it. If it is forgotten about, make sure to clear that memory before moving on. This is done with a simple flag variable being set. Patch 3 - When the tuning window is updated, the current pointer is just set adrift and not properly free'd. This patch catches that issue and removes the dangling pointer by holding a reference to the pointer until it is reset or specifically free'd. Patch 4 - Someone actually added in the code to create a onetime pretty-print array, this patch just puts it to use by setting the variable. Patch 5 - Limiting the buffer copy to the size of the allocated buffer with snprintf. Patch 6 - There exist some processes and entries that can and do extend beyond the length of these buffers. This limits those entries so as not to corrupt other memory on the system when in interactive mode. Patch 7 - This is an untested patch, but follows along the same lines of Patch 6. It applies the same principals only for the report method. Patch 8 - Creates a clean_shutdown function that can be used to cleanup the memory space at shutdown time. Calls upon parts of Patch 1 to make this happen. There will more than likely be some more patches in the future as time permits.
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<p class="MsoNormal"><span style="color:#1F497D">Sorry about a second post, looks like email stripped the attachements. Second attempt here.<o:p></o:p></span></p>
<p class="MsoNormal"><a name="_MailEndCompose"><span style="color:#1F497D"><o:p> </o:p></span></a></p>
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<p class="MsoNormal"><b>From:</b> PowerTop [mailto:[email protected]]
<b>On Behalf Of </b>Kalowsky, Daniel<br>
<b>Sent:</b> Tuesday, April 29, 2014 5:15 PM<br>
<b>To:</b> [email protected]<br>
<b>Subject:</b> [Powertop] A series of patches towards limiting memory corruption and foot print<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Hi Powertop,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I’ve been working with the interactive mode and have run into cases where powertop will crash due to a series of memory corruptions. The following series of patches have helped to reduce the frequency of the issue, although not completely
solved it. The issues arise much faster on platforms where there are constrained amounts of RAM to work within.
<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Patch 1 – When shutting down the interactive display, the display bits of memory is not correctly released. This patch provides a method for correctly doing so.
<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Patch 2 – Solving a documented memory leak with a non-elegant solution. The path either adds the bundle to the stack, or it forgets about it. If it is forgotten about, make sure to clear that memory before moving on. This is done with
a simple flag variable being set. <o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Patch 3 – When the tuning window is updated, the current pointer is just set adrift and not properly free’d. This patch catches that issue and removes the dangling pointer by holding a reference to the pointer until it is reset or specifically
free’d.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Patch 4 – Someone actually added in the code to create a onetime pretty-print array, this patch just puts it to use by setting the variable.
<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Patch 5 – Limiting the buffer copy to the size of the allocated buffer with snprintf.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Patch 6 – There exist some processes and entries that can and do extend beyond the length of these buffers. This limits those entries so as not to corrupt other memory on the system when in interactive mode.
<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Patch 7 – This is an untested patch, but follows along the same lines of Patch 6. It applies the same principals only for the report method.
<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Patch 8 – Creates a clean_shutdown function that can be used to cleanup the memory space at shutdown time. Calls upon parts of Patch 1 to make this happen.
<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">There will more than likely be some more patches in the future as time permits.
<o:p></o:p></p>
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