From: Igor Mammedov Date: Thu, 30 Apr 2020 15:46:06 +0000 (-0400) Subject: hostmem: don't use mbind() if host-nodes is empty X-Git-Tag: qemu-xen-4.15.0~162^2 X-Git-Url: http://xenbits.xensource.com/gitweb?a=commitdiff_plain;h=70b6d525dfb51d5e523d568d1139fc051bc223c5;p=qemu-xen.git hostmem: don't use mbind() if host-nodes is empty Since 5.0 QEMU uses hostmem backend for allocating main guest RAM. The backend however calls mbind() which is typically NOP in case of default policy/absent host-nodes bitmap. However when runing in container with black-listed mbind() syscall, QEMU fails to start with error "cannot bind memory to host NUMA nodes: Operation not permitted" even when user hasn't provided host-nodes to pin to explictly (which is the case with -m option) To fix issue, call mbind() only in case when user has provided host-nodes explicitly (i.e. host_nodes bitmap is not empty). That should allow to run QEMU in containers with black-listed mbind() without memory pinning. If QEMU provided memory-pinning is required user still has to white-list mbind() in container configuration. Reported-by: Manuel Hohmann Signed-off-by: Igor Mammedov Message-Id: <20200430154606.6421-1-imammedo@redhat.com> Tested-by: Philippe Mathieu-Daudé Cc: qemu-stable@nongnu.org Signed-off-by: Eduardo Habkost --- diff --git a/backends/hostmem.c b/backends/hostmem.c index 327f9eebc3..0efd7b7bd6 100644 --- a/backends/hostmem.c +++ b/backends/hostmem.c @@ -383,8 +383,10 @@ host_memory_backend_memory_complete(UserCreatable *uc, Error **errp) assert(sizeof(backend->host_nodes) >= BITS_TO_LONGS(MAX_NODES + 1) * sizeof(unsigned long)); assert(maxnode <= MAX_NODES); - if (mbind(ptr, sz, backend->policy, - maxnode ? backend->host_nodes : NULL, maxnode + 1, flags)) { + + if (maxnode && + mbind(ptr, sz, backend->policy, backend->host_nodes, maxnode + 1, + flags)) { if (backend->policy != MPOL_DEFAULT || errno != ENOSYS) { error_setg_errno(errp, errno, "cannot bind memory to host NUMA nodes");