Error Largest Free VMalloc Chunk: 0 B

Troubleshooting
1

Sample error for Memory: CRIT - RAM used: 172.21 MB of 980.41 MB, Swap used: 2.26 MB of 1.92 GB, Total virtual memory used: 174.47 MB of 2.88 GB (5.9%), Largest Free VMalloc Chunk: 0 B (warn/crit below 50 MB/30 MB) CRIT

I am seeing those in Ubuntu distro and I believe since Checkmk 1.6.0p8 and still on Checkmk 1.6.0p9. Not sure if it was present on Checkmk 1.6.0p7, though.

I tried exclude/ignore the error but has not been able to. Any clue how to go around that in WATO?

Thanks,
Rod

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Same problem here. I think it’s a bug in either the agent or the check plugin.

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The only workaround at the moment is to create a rule for the memory check with the following setting.
image

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Yes, that’s the workaround. The issue exists with 5.3 kernels as they seem to report the VMalloc Chunk differently (or not at all). The checkmk agent needs to be patched. I already opened a developer ticket for that issue.

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Thank you all. A workaround is all I needed for now. That did it! :slight_smile:

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I confirm this issue is now in all the servers with Ubuntu 20 (which uses kernel 5.4).

VmallocUsed and VmallocChunk in /proc/meminfo were set to 0 in 4.4 (here),
but now since 5.3 it’s used to “show the actual physical memory consumption of vmalloc()” (here)

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Can you point me to the ticket?

As far as i can tell from the master on github, the code was changed in april, but still only ignores only if BOTH values are zero
This was a ignore condition apparently introduced for the 4.4 Kernels, when both VMAlloc and VMAllocChunk were always returned as zero.
But since in the 5.x kernels, on reading /proc/meminfo, only VMallocChunk is not computed, but VMalloc again is, so the ignore condition does not apply anymore.

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Confirm same issue when i installed in Ubuntu 20

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This will be fixed with Werk 11303 in 1.6.0p16. Yes, p16. Coming :soon:

1 Like
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Hi, I found a quick workaround with patching the agent (1.60p19)
On line 139, you have (section <<<mem>>>)
grep -E -v '^Swap:|^Mem:|total:' </proc/meminfo
Just change to this :
grep -E -v '^Swap:|^Mem:|total:' </proc/meminfo | sed 's/VmallocChunk: 0 kB/VmallocChunk: 60000 kB/'
It will now report a fake, but correct value
Cheers,
Xavier
PS : the editor of the forum ate the spaces. Go to cat /proc/meminfo to get the exact number of spaces oruse a regex, I’mtoo lazy for it :slight_smile: