On Mon, Apr 19, 2010 at 07:01:33PM +0900, KAMEZAWA Hiroyuki wrote: > > mmotm 2010-04-15-14-42 > > When I tried > # echo 0 > /proc/sys/vm/compaction > > I see following. > > My enviroment was > 2.6.34-rc4-mm1+ (2010-04-15-14-42) (x86-64) CPUx8 > allocating tons of hugepages and reduce free memory. > > What I did was: > # echo 0 > /proc/sys/vm/compact_memory > > Hmm, I see this kind of error at migation for the 1st time.. > my.config is attached. Hmm... ? > > (I'm sorry I'll be offline soon.) That's ok, thanks you for the report. I'm afraid I made little progress as I spent most of the day on other bugs but I do have something for you. First, I reproduced the problem using your .config. However, the problem does not manifest with the .config I normally use which is derived from the distro kernel configuration (Debian Lenny). So, there is something in your .config that triggers the problem. I very strongly suspect this is an interaction between migration, compaction and page allocation debug. Compaction takes pages directly off the buddy list and I bet you a shiny penny they are still unmapped when the copy takes place resulting in your oops. I'll verify the theory tomorrow but it's a plausible explanation. On a different note, where did config options like the following come out of? CONFIG_ARCH_HWEIGHT_CFLAGS="-fcall-saved-rdi -fcall-saved-rsi -fcall-saved-rdx -fcall-saved-rcx -fcall-saved-r8 -fcall-saved-r9 -fcall-saved-r10 -fcall-saved-r11" I don't think they are a factor but I'm curious. -- Mel Gorman Part-time Phd Student Linux Technology Center University of Limerick IBM Dublin Software Lab -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>