Re: RELENG_7_0: vm_thread_new: kstack allocation failed

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Kostik Belousov wrote:
> On Tue, Jan 22, 2008 at 03:45:32PM -0800, Xin LI wrote:
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>> Hi,
>>
>> I have got a lot of this in dmesg output for RELENG_7_0 as of today:
>>
>> vm_thread_new: kstack allocation failed
>> vm_thread_new: kstack allocation failed
>> vm_thread_new: kstack allocation failed
>> vm_thread_new: kstack allocation failed
>> vm_thread_new: kstack allocation failed
>> vm_thread_new: kstack allocation failed
>>
>> Any idea?
> 
> Does it cause any problems aside from printing these messages ?

It causes some fork() to fail.

> What workload do you put on the machine ?

It was an rsync from NFS to ZFS with ~15M of files, and rsync will
consume basically all physical memory.  I end up with some 2GB active,
4GB wired thing. (The system has 8GB of RAM), and I added a "make -j9
buildworld" into the chaos to see if things get worse, and it did :-)

> The messages came from the failure of the kernel to allocate address
> space for the kernel stack for a thread being created. Previously, the
> system would panic encountering this situation.

Yes, I knew, previously it just panic and hangs there, and thanks a lot
for fixing it =-)

> This may happen due to kernel_map address space depletion, for instance,
> by having a lot (on i386 machines with > 1Gb memory, ~40000) threads.

It seems that I have hit some sort of "leak" or some exhaustion issue.
Say, when the workload is gone, the system did not recover from the
situation, and reboot worked fine.

The system is sort of in production and it is about 20 miles away from
my office.  Do you want me to do some experiments for this?

Cheers,
- --
Xin LI <delphij_at_delphij.net>	http://www.delphij.net/
FreeBSD - The Power to Serve!
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