RE: Broken memory management on system with no swap

Terry wrote:
> Lucky Green wrote:
> > There appears to be a memory management bug that affects systems 
> > without swap files. Processes are killed off due to the 
> server being 
> > "out of swap space" even though top shows some 800MB of "inactive" 
> > memory available.
> > 
> > Apr 18 18:13:25 pakastelohi kernel: swap_pager_getswapspace: failed
> 
> This is generally an attempt to get a swap mapping for 
> backing store for the process.  It could be that all your 
> "inactive" memory has been spoken for.

I had been under the impression that inactive pages contained data that
is no longer being used by a program, but is kept around in case the
data may be needed again in the future. Is it not the case that inactive
memory should be available to active processes if the processes require
more memory?

> > I suspect that for some reason memory listed as "inactive" 
> by top is 
> > not being correctly allocated to new processes when no swapfile is 
> > available, since the errors do not appear until memory listed as 
> > "free" has dropped to about 1.5-3k.
> 
> If you had provided a traceback, I would guess that this 
> happened as a call from swap_pager_reserve(), as opposed to a 
> call from
> swap_pager_strategy() or swap_pager_putpages().  This can 
> only happen if you are using an md device; are you using an 
> md device (ramdisk)?  If so: cut it out, or make sure the 
> MD_RESERVE bit is not set.

"device md" is compiled into the kernel, but to my knowledge I am not
using any MD devices. Should I remove this entry from the kernel config
file?

--Lucky