# Frequent segmentation faults

## post by starkj on Aug 4, 2023

Hi, I am using one of your Tensorbooks with an RTX 3080 laptop GPU and 16 cpus, running Ubuntu 20.04 for the past 1+ year. I am using it heavily, often leaving RL training jobs running overnight. It can get a bit hot to the touch, but nvidia-smi reports gpu temps (50-70 C) well below its warning threshold. My concern is that lately my software is frequently getting lots of segfaults (i.e. SIGSEGV) that I never used to see. It is not only in my RL models, which I am constantly modifying, but also in Tensorboard, installers and miniconda. This makes me wonder if it might be a hardware fault due to all the hard use.

Is there a toolset that I can use to do some hardware diagnostics, such as checking correct memory function? I don’t see anything on the boot menus.

Thank you.

## post by markd on Aug 8, 2023

SEGV or segfaults are caused when a code is attempting to access invalid or protected memory.

The reasons for this can be:

Software:

- Application has a bug and trying to allocate/use a incorrect memory address
  - This can be due to data the code uses, corrupt library, bug in the code it self

Hardware:
- Commonly a memory error or CPU/cache error

The easiest way to find a hardware error is look in dmesg or the kernel logs:

```bash
$ sudo dmesg | egrep "Hardware Error"
$ sudo zegrep "Hardware Error" /var/log/kern.log*
```

And to test for memory errors, you can boot from Memtest86

To test the memory, you’ll want to burn the [Memtest86 image](https://www.memtest86.com/downloads/memtest86-usb.zip) to a USB drive, boot into it, and run the test.

## post by starkj on Aug 13, 2023

Thanks [@markd](https://deeptalk.lambda.ai/u/markd). The first two commands show nothing, but I’m wondering how long such error information sticks around. I will set up a memtest86 drive & try that at my next boot opportunity.