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

Type: advisorySource: Official CVE List1 source record

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) and always drained `nr_to_scan`, guaranteeing the `-EAGAIN` requeue. Fix this in three steps: - Return `KEEP` instead of `TOUCH` when `expire_dir_lease` is `false`. If we are not going to reclaim the lease, leave it in place instead of churning the list and resetting its timestamp; the walk then terminates naturally (or via `STOP` at the first fresh lease). - Only return `-EAGAIN` from the first (dentry-lease) walk when something was actually freed. A full batch that frees nothing means retrying the sa

Announced Source revision 1
Original source ↗

CVE-2026-89647

Primary source · Revision 1

Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.

Security context

Source reference: cve:CVE-2026-89647

Linux

Source reference: /containers/cna/affected/0/product

Affected versions
Not stated in this record
Fixed versions
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Prerequisites
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Linux

Source reference: /containers/cna/affected/1/product

Affected versions
Not stated in this record
Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

Structured affected-version data

Original package identities and version rules from this source.

[
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "37c4efc1ddf98ba8b234d116d863a9464445901e",
        "lessThan": "dd2e9824e5e7dba406005ff779a107f773175a76",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "37c4efc1ddf98ba8b234d116d863a9464445901e",
        "lessThan": "5a541eb401acb89d791da41189d7a79220164b93",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "37c4efc1ddf98ba8b234d116d863a9464445901e",
        "lessThan": "37d6edb2f03b29399a3a337fae78674de51e1695",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "37c4efc1ddf98ba8b234d116d863a9464445901e",
        "lessThan": "3d122b2feb1dd76bb5041bdea5e1e1b007d8d415",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "37c4efc1ddf98ba8b234d116d863a9464445901e",
        "lessThan": "e7d7aa7b730178278109c41fa1b17b06873065d5",
        "versionType": "git"
      }
    ],
    "programFiles": [
      "fs/ceph/dir.c"
    ],
    "defaultStatus": "unaffected"
  },
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "5.1"
      },
      {
        "status": "unaffected",
        "version": "0",
        "lessThan": "5.1",
        "versionType": "semver"
      },
      {
        "status": "unaffected",
        "version": "6.6.160",
        "versionType": "semver",
        "lessThanOrEqual": "6.6.*"
      },
      {
        "status": "unaffected",
        "version": "6.12.109",
        "versionType": "semver",
        "lessThanOrEqual": "6.12.*"
      },
      {
        "status": "unaffected",
        "version": "6.18.50",
        "versionType": "semver",
        "lessThanOrEqual": "6.18.*"
      },
      {
        "status": "unaffected",
        "version": "7.2.4",
        "versionType": "semver",
        "lessThanOrEqual": "7.2.*"
      },
      {
        "status": "unaffected",
        "version": "7.3",
        "versionType": "original_commit_for_fix",
        "lessThanOrEqual": "*"
      }
    ],
    "programFiles": [
      "fs/ceph/dir.c"
    ],
    "defaultStatus": "affected"
  }
]
Related CVEs
CVE-2026-89647

Source reference: /cveMetadata/cveId

Publisher severity

high

Source reference: /containers/cna/metrics

Event
#46697 · Revision 1
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Publisher date
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