On 18.07.2016 11:26, Greg Kurz wrote: > On Mon, 18 Jul 2016 11:04:39 +0200 > Thomas Huth <[email protected]> wrote: > >> On 18.07.2016 10:59, Greg Kurz wrote: >>> On Mon, 18 Jul 2016 10:52:36 +1000 >>> David Gibson <[email protected]> wrote: >>> >>>> On Fri, Jul 15, 2016 at 10:10:25AM +0200, Thomas Huth wrote: >>>>> Commit 86b50f2e1bef ("Disable huge page support if it is not available >>>>> for main RAM") already made sure that huge page support is not announced >>>>> to the guest if the normal RAM of non-NUMA configurations is not backed >>>>> by a huge page filesystem. However, there is one more case that can go >>>>> wrong: NUMA is enabled, but the RAM of the NUMA nodes are not configured >>>>> with huge page support (and only the memory of a DIMM is configured with >>>>> it). When QEMU is started with the following command line for example, >>>>> the Linux guest currently crashes because it is trying to use huge pages >>>>> on a memory region that does not support huge pages: >>>>> >>>>> qemu-system-ppc64 -enable-kvm ... -m 1G,slots=4,maxmem=32G -object \ >>>>> >>>>> memory-backend-file,policy=default,mem-path=/hugepages,size=1G,id=mem-mem1 >>>>> \ >>>>> -device pc-dimm,id=dimm-mem1,memdev=mem-mem1 -smp 2 \ >>>>> -numa node,nodeid=0 -numa node,nodeid=1 >>>>> >>>>> To fix this issue, we've got to make sure to disable huge page support, >>>>> too, when there is a NUMA node that is not using a memory backend with >>>>> huge page support. >>>>> >>>>> Fixes: 86b50f2e1befc33407bdfeb6f45f7b0d2439a740 >>>>> Signed-off-by: Thomas Huth <[email protected]> >>>>> --- >>>>> target-ppc/kvm.c | 10 +++++++--- >>>>> 1 file changed, 7 insertions(+), 3 deletions(-) >>>> >>>> Applied to ppc-for-2.7, thanks. >>>> >>> >>> It looks like my replies to this patch were ignored... no big deal though >>> :) >> >> I'll try to come up with an additional patch that fixes the remaining >> problem that you've found... Meanwhile, did you find out why you get >> that assertion that I was not able to recreate? Could you maybe post the >> exact command line to trigger that assertion? >> > > I hit the assertion when I specify pc-dimm devices on the command line: > > qemu-system-ppc64 -enable-kvm ... -m 2G,slots=4,maxmem=32G \ > -object > memory-backend-file,policy=default,mem-path=/mnt/kvm_hugepage,size=1G,id=mem-mem1 > \ > -device pc-dimm,id=dimm-mem1,memdev=mem-mem1 \ > -object memory-backend-file,policy=default,mem-path=/mnt,size=1G,id=mem-mem2 > \ > -device pc-dimm,id=dimm-mem2,memdev=mem-mem2 \ > -smp 2 -numa node,nodeid=0,memdev=mem-mem1 \ > -numa node,nodeid=1,memdev=mem-mem2
FWIW, with that command line, I still don't get an assertion but a normal error message: qemu-system-ppc64: -device pc-dimm,id=dimm-mem1,memdev=mem-mem1: can't use already busy memdev: mem-mem1 Thomas
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