[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 08:47:22AM +0000, 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 Daniel tells me it is due to the recent changes in the balloon code. CC-ing him here. > > 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] > > 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. > > Thanks, > James > > > _______________________________________________ > 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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