MariaDB crashes with Xen PVH - mysqld got signal 11

Hello,
after upgrading our Gentoo Linux systems to latest stable versions, one of our MariaDB instance started to crash. The crashes seems to be random at times like:

160527 9:34:05 [ERROR] mysqld got signal 11 ;
160527 13:52:37 [ERROR] mysqld got signal 11 ;
160530 20:46:51 [ERROR] mysqld got signal 11 ;
160602 5:32:48 [ERROR] mysqld got signal 11 ;

We have a master-slave replication. We first upgraded the slave to 10.0.25, had it running for 2 weeks without problems. Then we did a master failover, it worked for a week and then it started to crash. First it crashed on MariaDB 10.0.25, then again on 10.0.25. We downgraded to MariaDB 10.0.23 (that version worked before the system update), but it crashed again. Then we switched back to the old master instance (failover) with MariaDB 10.0.23, but it crashed again.

The MariaDB instances are running virtualized as Xen DomU (in pvh mode) on Linux Kernel 4.1.24 with 230GB RAM / 24 vcpus. MariaDB was compiled with the following Gentoo USE flags: "extraengine jemalloc openssl pam server".

The database is mostly used for selects (1000-3000 qps).