RHEL7: While operating on a Veritas filesystem, kmalloc-1024 slab caches take all resources

Issue

• When the customer does rman backups (on veritas filesystem) and some SQL queries (in databases ontop of veritas filesystem), The "kmalloc-1024" buffer (part of "cat /proc/slabinfo" output) grows until the system has no memory left. So under usage, the buffer constantly grows, and after some weeks memory is used up.

• The issue is seen on multiple systems.

• The kmalloc-1024 cache only seems to grow with pread and pwrite.

• Memory is not shrinking when veritas filesystems are umounted.

• Unloading the veritas modules is not possible

• Dropping caches using /proc/sys/vm/drop_caches does not influence that memory.

• "-/+ buffers/cache" in the "free" output is decreasing when the filesystem is used and kmalloc-1024 is growing.

• Simpler tools like dd, cp, tar etc. were not able to reproduce the issue.

• Normal tools like cp, tar etc. use read/write. Tools like rman use "pread" and "pwrite", these seem to cause the issue