Hello,

I am dealing with VM disk images and performing something like wiping
free space to prepare image for compressing and storing on server or
copying it to external USB disk causes

1) system lockup in order of a few tens of seconds when all CPU cores
are 100% used by system and the machine is basicaly unusable

2) oom killer killing processes

This all on system with 8G ram so there should be plenty space to work with.

This happens with kernels 3.6.4 or 3.7.1

With earlier kernel versions (some 3.0 or 3.2 kernels) this was not a
problem even with less ram.

I have  vm.swappiness = 0 set for a long  time already.

Presumably the kernel should stop the process writing to disk from
creating more buffers and write out some rather than start killing
processes to free memory. Also it might use some swap even with zero
swappiness when there is no other way to free more space. Earlier
kernels certainly did that.

Thanks

Michal