Document GH#1505, bind() bug in kernel 6.0

Author: peterroth

KNOWN_ISSUES.md

@@ -13,3 +13,8 @@
   **Effected Versions:** 4.10.0-0.okd-2022-03-07-131213
   **Description:** Due to kernel 4.16 bug CephFS mounts get invalid permissions, so writing to image registry backed by CephFS fails on OKD 4.10
   **Workaround**: In `ceph-csi-cephfs` installation add `wsync` to `kernelMountOptions`
+
+## [Ceph service performance degradation](https://github.com/okd-project/okd/issues/1505)
+  **Effected Versions:** 4.11.0-0.okd-2023-01-14-152430, 4.12.0-0.okd-2023-02-04-212953
+  **Description:** Due to kernel 6.0 bug with bind(), the Ceph service faces radical performance degradation, causing PG unavailability, very slow I/O operations.
+  **Workaround**: Either build a custom [FCOS image using layering](https://docs.okd.io/4.12/post_installation_configuration/coreos-layering.html) or update to a newer version.