[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] kernel log flooded with: xen_balloon: reserve_additional_memory: add_memory() failed: -17
On Wed, Dec 19, 2012 at 10:55:49AM +0000, James Dingwall wrote: > On 2012-12-19 08:47, James Dingwall wrote: > >Hi, > > > >I have encountered an apparently benign error on two systems where > >the dom0 kernel log is flooded with messages like: > > > >[52482.163855] System RAM resource [mem 0x1b8000000-0x1bfffffff] > >cannot be added > >[52482.163860] xen_balloon: reserve_additional_memory: > >add_memory() failed: -17 > > > >The first line is from drivers/xen/xen-balloon.c, the second from > >mm/memory_hotplug.c > > > >The trigger for the messages seems to be the first occasion that a > >Xen guest is shutdown. I have noted this in a vanilla 3.6.7 and > >kernel 3.5.0-18 built from Ubuntu sources. Xen version is 4.2.0. It > >is not clear why the dom0 is kernel is trying to balloon up as the > >Xen > >command line is specifies a fixed dom0 memory allocation and > >noselfballooning is specified for the kernel and ballooning is also > >disabled in the xend-config.sxp / xl.conf (one system using xm, > >another xl) > > > >xen command line: > >placeholder xsave=0 iommu=0 console=vga,com2 com2=115200,8n1 > >dom0_mem=max:6144m > > > >kernel command line: > >root=/dev/loop0 ro console=tty1 console=hvc0 earlyprintk=xen > >nomodeset noselfballooning > > > >Examining /proc/iomem does show that the dom0 memory allocation is > >actually 64kb short of 6144Mb: > > > >cat /proc/iomem | grep System\ RAM > >00010000-0009bfff : System RAM [573440 bytes] > >00100000-cb2dffff : System RAM [3407740928 bytes] > >100000000-1b4d83fff : System RAM [3034071040 bytes] > > > >Total system ram: 6442385408 - 6x2^30 = 65536 > > > >The memory range indicated in the log message is "Unusable memory" in > >/proc/iomem: > >1b4d84000-82fffffff : Unusable memory > > > >Another point of interest is that we have multiple "identical" > >hardware platforms (Dell T320) for the system running the 3.5.0-18 > >kernel but only see this error on a slightly more recent system. > >Older systems show in /proc/iomem that all memory is System RAM. > > > >100000000-82fffffff : System RAM [older system BIOS 1.0] Wow. That is a lot of memory :-) > > > >100000000-1b4d83fff : System RAM [newer system BIOS 1.3] > >1b4d84000-82fffffff : Unusable memory > > > >The BIOS revision between the old and new has changed so I was > >wondering if it is possible that there is a white list which affects > >the impact of the kernel option: > >CONFIG_X86_RESERVE_LOW=64 > >This is only a guess since the amount of memory reserved is > >equivalent to the short fall calculated above. If this is the right > >area perhaps the dom0 calculation for its memory entitlement needs to > >be taught to not to try and hotplug the missing 64k when it has been > >reserved. > > > >If any other information would be useful then please let me know. > > With some further investigation we have determined that the > different BIOS version does not seem to be a factor and the key > point is actually the Xen command line. The reason that we had max: > specified is that without it we could not boot the kernel/xen > combination on an AMD platform. I will do some further testing to What happend? Did you report it in another email on this mailing list? > see what the result of dom0_mem=6144m,max:6144m as suggested > http://wiki.xen.org/wiki/Xen_Best_Practices gets us. > > placeholder xsave=0 iommu=0 console=vga,com2 com2=115200,8n1 > dom0_mem=max:6144m I think you don't need xsave=0 anymore? It was only needed with a Fedora stock kernel (and the underlaying issue I believe is now fixed). > results in /proc/iomem having an unusable range and top reports > 6083900k of memory in dom0 > > placeholder xsave=0 iommu=0 console=vga,com2 com2=115200,8n1 > dom0_mem=6144m > no unusable range, top reports 5605976k of memory in dom0 and no log > messages Hmm.. If you were to run this with 'loglevel=8 debug' with the dom0_mem=6144m and dom0_mem=max:6144m could you send both 'xl dmesg' and 'dmesg' outputs? > > > _______________________________________________ > Xen-devel mailing list > Xen-devel@xxxxxxxxxxxxx > http://lists.xen.org/xen-devel > _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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