On Tue, 2013-04-30 at 19:58 +0100, Daniel Kiper wrote: > On Tue, Apr 30, 2013 at 02:44:18PM +0100, Ian Campbell wrote: > > On Tue, 2013-04-30 at 13:59 +0100, Daniel Kiper wrote: > > > On Mon, Apr 29, 2013 at 03:44:09PM +0100, Ian Campbell wrote: > > > > On Mon, 2013-04-29 at 12:37 +0100, Daniel Kiper wrote: > > > > > > > > > This patch enforces on target limit statically defined in Linux Kernel > > > > > source and limit defined by hypervisor or host. This way the balloon > > > > > driver should not attempt to populate pages above given limits > > > > > because they may fail. > > > > > > > > > > Particularly this patch fixes bug which led to flood > > > > > of dom0 kernel log with messages similar to: > > > > > > > > > > System RAM resource [mem 0x1b8000000-0x1bfffffff] cannot be added > > > > > xen_balloon: reserve_additional_memory: add_memory() failed: -17 > > > > > > > > I think it would be OK to simply tone down this message (and perhaps add > > > > the failed pages to the balloon, if that makes sense). This isn't > > > > dissimilar to increase_reservation failing. > > > > > > If add_memory() fails it is hard error. It means that we do not > > > know where new or ballooned pages should be placed. > > > > I see that add_memory() is a generic or arch level function rather than > > a ballooning specific one. Under what circumstances can it fail and how > > do they relate the the setting of the balloon target? > > It is generic function with some references to arch code. It is called > when pages could not be taken from balloon any more and must be hotplugged. > It reserves memory resource (start address and size is calculated on the > base of target and max_pfn) and build some structures for new memory. > It may fail in many places. In this case it failed because placement > of new resource was incorrectly calculated because algorithm is very > simple and not cover all cases. I am going to fix this issue but > a bit later.
I think you should fix that core issue first, otherwise the requirement for messing with the balloon target is not very obvious. Ian. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
