Hi, When running big mapreduce operation with pyspark (in the particular case using lot of sets and operations on sets in the map tasks so likely to be allocating and freeing loads of pages) I eventually get kernel error 'python: page allocation failure: order:10, mode:0x2000d0' plus very verbose dump which I can reduce to following snippet: Node 1 Normal: 3601*4kB (UEM) 3159*8kB (UEM) 1669*16kB (UEM) 763*32kB (UEM) 1451*64kB (UEM) 15*128kB (UM) 1*256kB (U) 0*512kB 0*1024kB 0*2048kB 0*4096kB = 185836kB ...SLAB: Unable to allocate memory on node 1 (gfp=0xd0) cache: size-4194304, object size: 4194304, order: 10 so simply the memory got fragmented and there are no higher order pages. interesting thing is that there is no error thrown by spark itself - the processing just gets stuck without any error or anything (only the kernel dmesg explains what happened in the background). any kernel experts out there with an advice how to avoid this? have tried few vm options but still no joy. running spark 1.2.0 (cdh 5.3.0) on kernel 3.8.13 thanks,Antony.