CVE-2026-89647

/// Technical description

In the Linux kernel, the following vulnerability has been resolved:

ceph: do not repeat ceph_trim_dentries() if no progress possible

ceph_cap_reclaim_work() re-queues itself for as long as

ceph_trim_dentries() returns -EAGAIN, which happens whenever a lease

walk exhausts its `nr_to_scan` budget. This creates a busy loop that

consumes CPU without making any progress when there is nothing to

reclaim: with no cap pressure (`count==0`) and every scanned lease

still valid, each pass runs the full scan budget down to zero and

returns `-EAGAIN`, only to be queued again immediately.

The dir-lease walk made this worse. When `expire_dir_lease` is

`false` (i.e. we have no intention of reclaiming dir leases),

__dir_lease_check() returned `TOUCH` for every valid lease. `TOUCH`

moves the dentry to the tail of the list and resets `di->time` via

__dentry_dir_lease_touch(), so a walk over N valid leases pointlessly

rewrote the list, refreshed the timestamps (preventing them from ever

aging out) a

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References