[libvirt] [PATCH v2] qemuBuildMemoryBackendStr: Don't crash if no hugetlbfs is mounted
When trying to migrate a huge page enabled guest, I've noticed
the following crash. Apparently, if no specific hugepages are
requested:
<memoryBacking>
<hugepages/>
</memoryBacking>
and there are no hugepages configured on the destination, we try
to dereference a NULL pointer.
Program received signal SIGSEGV, Segmentation fault.
0x00007fcc907fb20e in qemuGetHugepagePath (hugepage=0x0) at qemu/qemu_conf.c:1447
1447 if (virAsprintf(&ret, "%s/libvirt/qemu", hugepage->mnt_dir)
< 0)
(gdb) bt
#0 0x00007fcc907fb20e in qemuGetHugepagePath (hugepage=0x0) at qemu/qemu_conf.c:1447
#1 0x00007fcc907fb2f5 in qemuGetDefaultHugepath (hugetlbfs=0x0, nhugetlbfs=0) at
qemu/qemu_conf.c:1466
#2 0x00007fcc907b4afa in qemuBuildMemoryBackendStr (size=4194304, pagesize=0,
guestNode=0, userNodeset=0x0, autoNodeset=0x0, def=0x7fcc70019070,
qemuCaps=0x7fcc70004000, cfg=0x7fcc5c011800, backendType=0x7fcc95087228,
backendProps=0x7fcc95087218,
force=false) at qemu/qemu_command.c:3297
#3 0x00007fcc907b4f91 in qemuBuildMemoryCellBackendStr (def=0x7fcc70019070,
qemuCaps=0x7fcc70004000, cfg=0x7fcc5c011800, cell=0, auto_nodeset=0x0,
backendStr=0x7fcc70020360) at qemu/qemu_command.c:3413
#4 0x00007fcc907c0406 in qemuBuildNumaArgStr (cfg=0x7fcc5c011800, def=0x7fcc70019070,
cmd=0x7fcc700040c0, qemuCaps=0x7fcc70004000, auto_nodeset=0x0) at
qemu/qemu_command.c:7470
#5 0x00007fcc907c5fdf in qemuBuildCommandLine (driver=0x7fcc5c07b8a0,
logManager=0x7fcc70003c00, def=0x7fcc70019070, monitor_chr=0x7fcc70004bb0,
monitor_json=true, qemuCaps=0x7fcc70004000, migrateURI=0x7fcc700199c0 "defer",
snapshot=0x0,
vmop=VIR_NETDEV_VPORT_PROFILE_OP_MIGRATE_IN_START, standalone=false, enableFips=false,
nodeset=0x0, nnicindexes=0x7fcc95087498, nicindexes=0x7fcc950874a0,
domainLibDir=0x7fcc700047c0 "/var/lib/libvirt/qemu/domain-1-fedora") at
qemu/qemu_command.c:9547
Signed-off-by: Michal Privoznik <mprivozn(a)redhat.com>
---
diff to v1:
- added a comment to qemuGetDefaultHugepath() as requested in the review
src/qemu/qemu_command.c | 6 ++++++
src/qemu/qemu_conf.c | 10 ++++++++++
2 files changed, 16 insertions(+)
diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c
index 038c38f..0bafc3f 100644
--- a/src/qemu/qemu_command.c
+++ b/src/qemu/qemu_command.c
@@ -3294,6 +3294,12 @@ qemuBuildMemoryBackendStr(unsigned long long size,
if (!(mem_path = qemuGetHugepagePath(&cfg->hugetlbfs[i])))
goto cleanup;
} else {
+ if (!cfg->nhugetlbfs) {
+ virReportError(VIR_ERR_INTERNAL_ERROR,
+ "%s", _("hugetlbfs filesystem is not
mounted "
+ "or disabled by administrator
config"));
+ goto cleanup;
+ }
if (!(mem_path = qemuGetDefaultHugepath(cfg->hugetlbfs,
cfg->nhugetlbfs)))
goto cleanup;
diff --git a/src/qemu/qemu_conf.c b/src/qemu/qemu_conf.c
index dad8334..901ad23 100644
--- a/src/qemu/qemu_conf.c
+++ b/src/qemu/qemu_conf.c
@@ -1450,6 +1450,16 @@ qemuGetHugepagePath(virHugeTLBFSPtr hugepage)
return ret;
}
+
+/**
+ * qemuGetDefaultHugepath:
+ *
+ * Get default hugepages path for memory backend. Does not work
+ * well with @nhugetlbfs == 0 or @hugetlbfs == NULL.
+ *
+ * Returns 0 on success,
+ * -1 otherwise.
+ * */
char *
qemuGetDefaultHugepath(virHugeTLBFSPtr hugetlbfs,
size_t nhugetlbfs)
--
2.8.4