Simple reproducer: qemu.git $ ./build/qemu-system-x86_64 \ -m size=8389632k,slots=16,maxmem=25600000k \ -object '{"qom-type":"memory-backend-file","id":"ram-node0","mem-path":"/hugepages2M/","prealloc":true,"size":8590983168,"host-nodes":[0],"policy":"bind"}' \ -numa node,nodeid=0,cpus=0,memdev=ram-node0
With current master I get: qemu-system-x86_64: cannot bind memory to host NUMA nodes: Invalid argument The problem is that memory size (8193MiB) is not an integer multiple of underlying pagesize (2MiB) which triggers a check inside of madvise(), since we can't really set a madvise() policy just to a fraction of a page. Signed-off-by: Michal Privoznik <mpriv...@redhat.com> --- backends/hostmem.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/backends/hostmem.c b/backends/hostmem.c index 747e7838c0..4e88d048de 100644 --- a/backends/hostmem.c +++ b/backends/hostmem.c @@ -326,9 +326,10 @@ host_memory_backend_memory_complete(UserCreatable *uc, Error **errp) HostMemoryBackendClass *bc = MEMORY_BACKEND_GET_CLASS(uc); Error *local_err = NULL; void *ptr; - uint64_t sz; if (bc->alloc) { + uint64_t sz; + bc->alloc(backend, &local_err); if (local_err) { goto out; @@ -337,6 +338,11 @@ host_memory_backend_memory_complete(UserCreatable *uc, Error **errp) ptr = memory_region_get_ram_ptr(&backend->mr); sz = memory_region_size(&backend->mr); + /* Round up size to be an integer multiple of pagesize, because + * madvise() does not really like setting advices on a fraction of a + * page. */ + sz = ROUND_UP(sz, qemu_ram_pagesize(backend->mr.ram_block)); + if (backend->merge) { qemu_madvise(ptr, sz, QEMU_MADV_MERGEABLE); } -- 2.41.0