Reboot after panic: kalloc: out of kernel virtual space

[Radhakrishnan Venkatara]

Hi,

My K570 system got rebooted yesterday at 9:30pm. In /etc/shutdownlog it refers
like this
21:32 Mon Apr 21 2003. Reboot after panic: kalloc: out of kernel virtual space

what does this mean ? This something to do with the reserved memory.

In my OLDsyslog.log there is an entry it is given below

Apr 21 11:55:31 jump vmunix: System is close to kernel virtual memory limit (KVM
LIMIT).
Apr 21 11:55:31 jump vmunix: This is an abnormal condition and the kernel will a
ttempt to
Apr 21 11:55:31 jump vmunix: reclaim some space. Please check the tunable parame
ters.

according to this some parameter limit has been reached. which parameter i have to check.
I checked using glance the parameters such as nflocks,nfiles are ok.

please throw some light.

thanx

radhakrishnan

[Michael Tully]

Sounds like you've ran out of swap. Please advise your current kernel parameters. You may be able to free up some virtual memory by setting your buffer cache setting lower and increasing the amount of swap space currently in use.

[Michael Steele_2]

A "kalloc: out of kernel virtual space" panic is typically caused due to sysmap fragmentation. This is fixed by increasing the size of the kernel parameter nproc

http://forums.itrc.hp.com/cm/QuestionAnswer/1,,0x126737f45ef7d4118fef0090279cd0f9,00.html

[Steven E. Protter]

It would be useful for diagnosis if you provided the following information:

Output of the kmtune command, run as root, no parameters.

swapinfo

Because I won't be awake to see the answer a few shots in the dark based on the prior two posts.

On systems with memory of less than 16 Gig, the rule of thumb is swap should be 1.5 to 2.0 times physical memory. It might not all ever get used, but it will make your system stable when pushed hard.

With regards to nproc, with Oracle and all running on my boxes, I've set that as high as possible, 8192 with the necessary adjustments in other kernel parameters that are based on nproc. I had to change a few formula's but I got a nice stable system for my trouble.

I'm attaching a background performance monitoring script that can collect more data. I'd be careful running it since your system seems on the edge.

Last thought: Have you made any recent kernel changes? If so, consider backing them out by copying /stand/vmunix.prev over vmunix. Might want to make sure you have a good make_tape_recovery backup too.

SEP

[Jon Finley]

Michael S. called it. You need to tune nproc.

From HP: (A "kalloc: out of kernel virtual space" panic is typically caused due to
sysmap fragmentation. This is fixed by increasing the size of the
kernel parameter nproc.)

http://www2.itrc.hp.com/service/cki/docDisplay.do?docLocale=en_US&docId=200000065679489

Jon

[Radhakrishnan Venkatara]

hi,

thanks for all ur replies.
I send anaylized crash dump and i send the output hp also.
its same system fragmentation issue and some KVMLIMIT issue which requires specific patches.
HP has to comeback on that , once they send me the details i will post the same.

thanx
radhakrishnan