FKIE_CVE-2026-80719

Vulnerability from fkie_nvd - Published: 2026-08-28 08:16 - Updated: 2026-08-28 08:16
Severity
Summary
In the Linux kernel, the following vulnerability has been resolved: mm: mglru: fix stale batch updates after memcg reparenting The mglru page table walker batches per-generation size deltas in walk->nr_pages while walking page tables without holding the lruvec lock. The reset_batch_size() later folds those deltas into walk->lruvec under the lruvec lock. The page table walker can run concurrently with the memcg reparenting path as follows: CPU0 CPU1 ==== ==== walk_mm --> walk_page_range --> update_batch_size --> walk->nr_pages += delta mem_cgroup_css_offline --> memcg_reparent_objcgs --> lock lruvec lru_gen_reparent_memcg --> reparent child folios to parent unlock lruvec lock lruvec reset_batch_size --> child lrugen->nr_pages += delta This will trigger the following warning in lru_gen_exit_memcg(): VM_WARN_ON_ONCE(memchr_inv(lruvec->lrugen.nr_pages, 0, sizeof(lruvec->lrugen.nr_pages))); And the user-visible impact of underestimated nr_pages in MGLRU was premature OOMs because MGLRU does not try to reclaim memory when nr_pages reaches zero, but there are still more pages. To fix it, make reset_batch_size() check CSS_DYING under RCU before flushing the pending batch. A non-dying memcg keeps the original lruvec stable against RCU-delayed offlining; a dying memcg redirects the deltas to the first non-dying ancestor.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/de4660898b7aa7e03d3b120a6bfa6b26211e4e77
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/fceb6b7f3ddec6ea9fc11577f4cf1b2da73a3101
Impacted products
Vendor Product Version
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "include/linux/memcontrol.h",
            "mm/vmscan.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "fceb6b7f3ddec6ea9fc11577f4cf1b2da73a3101",
              "status": "affected",
              "version": "f304652609eae3814b0e9d11c75c0e0cb62da31f",
              "versionType": "git"
            },
            {
              "lessThan": "de4660898b7aa7e03d3b120a6bfa6b26211e4e77",
              "status": "affected",
              "version": "f304652609eae3814b0e9d11c75c0e0cb62da31f",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "include/linux/memcontrol.h",
            "mm/vmscan.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "7.1"
            },
            {
              "lessThan": "7.1",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.1.*",
              "status": "unaffected",
              "version": "7.1.8",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nmm: mglru: fix stale batch updates after memcg reparenting\n\nThe mglru page table walker batches per-generation size deltas in\nwalk-\u003enr_pages while walking page tables without holding the lruvec lock. \nThe reset_batch_size() later folds those deltas into walk-\u003elruvec under\nthe lruvec lock.\n\nThe page table walker can run concurrently with the memcg reparenting path\nas follows:\n\nCPU0                           CPU1\n====                           ====\n\nwalk_mm\n--\u003e walk_page_range\n    --\u003e update_batch_size\n        --\u003e walk-\u003enr_pages += delta\n\n                              mem_cgroup_css_offline\n                              --\u003e memcg_reparent_objcgs\n                                  --\u003e lock lruvec\n                                      lru_gen_reparent_memcg\n                                      --\u003e reparent child folios to parent\n                                      unlock lruvec\n\n    lock lruvec\n    reset_batch_size\n    --\u003e child lrugen-\u003enr_pages += delta\n\nThis will trigger the following warning in lru_gen_exit_memcg():\n\n\tVM_WARN_ON_ONCE(memchr_inv(lruvec-\u003elrugen.nr_pages, 0,\n\t\t\t\t   sizeof(lruvec-\u003elrugen.nr_pages)));\n\nAnd the user-visible impact of underestimated nr_pages in MGLRU was\npremature OOMs because MGLRU does not try to reclaim memory when nr_pages\nreaches zero, but there are still more pages.\n\nTo fix it, make reset_batch_size() check CSS_DYING under RCU before\nflushing the pending batch.  A non-dying memcg keeps the original lruvec\nstable against RCU-delayed offlining; a dying memcg redirects the deltas\nto the first non-dying ancestor."
    }
  ],
  "id": "CVE-2026-80719",
  "lastModified": "2026-08-28T08:16:57.720",
  "metrics": {},
  "published": "2026-08-28T08:16:57.720",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/de4660898b7aa7e03d3b120a6bfa6b26211e4e77"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/fceb6b7f3ddec6ea9fc11577f4cf1b2da73a3101"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Received"
}



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