On Wed, Aug 13, 2014 at 07:21:57PM +0800, zhanghailiang wrote: > If we configure qemu with realtime-mlock-on and memory-node-bind at the same > time, > Qemu will fail to start, and mbind() fails with message "Input/output error". > > >From man page: > int mbind(void *addr, unsigned long len, int mode, > unsigned long *nodemask, unsigned long maxnode, > unsigned flags); > The *MPOL_BIND* mode specifies a strict policy that restricts memory > allocation > to the nodes specified in nodemask. > If *MPOL_MF_STRICT* is passed in flags and policy is not MPOL_DEFAULT(In qemu > here is MPOL_BIND), then the call will fail with the error EIO if the existing > pages in the memory range don't follow the policy. > > The memory locked ahead by mlockall can not guarantee to follow the policy > above, > And if that happens, it will result in an EIO error. > > So we should call mlock after mbind, here we adjust the place where called > mlock, > Move it to function pc_memory_init. > > Signed-off-by: xiexiangyou <xiexiang...@huawei.com> > Signed-off-by: zhanghailiang <zhang.zhanghaili...@huawei.com>
OK but won't this still fail in case of memory hotplug? We set MCL_FUTURE so the same will apply? Maybe it's enough to set MPOL_MF_MOVE? Does the following work for you? --> hostmem: set MPOL_MF_MOVE When memory is allocated on a wrong node, MPOL_MF_STRICT doesn't move it - it just fails the allocation. A simple way to reproduce the failure is with mlock=on realtime feature. The code comment actually says: "ensure policy won't be ignored" so setting MPOL_MF_MOVE seems like a better way to do this. Signed-off-by: Michael S. Tsirkin <m...@redhat.com> --- diff --git a/backends/hostmem.c b/backends/hostmem.c index ca10c51..a9905c0 100644 --- a/backends/hostmem.c +++ b/backends/hostmem.c @@ -304,7 +304,7 @@ host_memory_backend_memory_complete(UserCreatable *uc, Error **errp) /* ensure policy won't be ignored in case memory is preallocated * before mbind(). note: MPOL_MF_STRICT is ignored on hugepages so * this doesn't catch hugepage case. */ - unsigned flags = MPOL_MF_STRICT; + unsigned flags = MPOL_MF_STRICT | MPOL_MF_MOVE; /* check for invalid host-nodes and policies and give more verbose * error messages than mbind(). */ -- MST