{"id":"CVE-2026-80719","state":"PUBLISHED","title":"mm: mglru: fix stale batch updates after memcg reparenting","description":"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->nr_pages while walking page tables without holding the lruvec lock. \nThe reset_batch_size() later folds those deltas into walk->lruvec 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--> walk_page_range\n    --> update_batch_size\n        --> walk->nr_pages += delta\n\n                              mem_cgroup_css_offline\n                              --> memcg_reparent_objcgs\n                                  --> lock lruvec\n                                      lru_gen_reparent_memcg\n                                      --> reparent child folios to parent\n                                      unlock lruvec\n\n    lock lruvec\n    reset_batch_size\n    --> child lrugen->nr_pages += delta\n\nThis will trigger the following warning in lru_gen_exit_memcg():\n\n\tVM_WARN_ON_ONCE(memchr_inv(lruvec->lrugen.nr_pages, 0,\n\t\t\t\t   sizeof(lruvec->lrugen.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.","publishedAt":"2026-08-28T06:53:16.087Z","updatedAt":"2026-08-28T06:53:16.087Z","severity":null,"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"f304652609eae3814b0e9d11c75c0e0cb62da31f","status":"affected","lessThan":"fceb6b7f3ddec6ea9fc11577f4cf1b2da73a3101","versionType":"git"},{"version":"f304652609eae3814b0e9d11c75c0e0cb62da31f","status":"affected","lessThan":"de4660898b7aa7e03d3b120a6bfa6b26211e4e77","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["include/linux/memcontrol.h","mm/vmscan.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"7.1","status":"affected"},{"version":"0","status":"unaffected","lessThan":"7.1","versionType":"semver"},{"version":"7.1.8","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["include/linux/memcontrol.h","mm/vmscan.c"]}],"references":["https://git.kernel.org/stable/c/fceb6b7f3ddec6ea9fc11577f4cf1b2da73a3101","https://git.kernel.org/stable/c/de4660898b7aa7e03d3b120a6bfa6b26211e4e77"],"weaknesses":[],"ingestedAt":"2026-10-29T20:13:07.220Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/80xxx/CVE-2026-80719.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-80719","state":"PUBLISHED","datePublished":"2026-08-28T06:53:16.087Z","dateUpdated":"2026-08-28T06:53:16.087Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-08-26T14:34:25.788Z"},"containers":{"cna":{"title":"mm: mglru: fix stale batch updates after memcg reparenting","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->nr_pages while walking page tables without holding the lruvec lock. \nThe reset_batch_size() later folds those deltas into walk->lruvec 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--> walk_page_range\n    --> update_batch_size\n        --> walk->nr_pages += delta\n\n                              mem_cgroup_css_offline\n                              --> memcg_reparent_objcgs\n                                  --> lock lruvec\n                                      lru_gen_reparent_memcg\n                                      --> reparent child folios to parent\n                                      unlock lruvec\n\n    lock lruvec\n    reset_batch_size\n    --> child lrugen->nr_pages += delta\n\nThis will trigger the following warning in lru_gen_exit_memcg():\n\n\tVM_WARN_ON_ONCE(memchr_inv(lruvec->lrugen.nr_pages, 0,\n\t\t\t\t   sizeof(lruvec->lrugen.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."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"f304652609eae3814b0e9d11c75c0e0cb62da31f","status":"affected","lessThan":"fceb6b7f3ddec6ea9fc11577f4cf1b2da73a3101","versionType":"git"},{"version":"f304652609eae3814b0e9d11c75c0e0cb62da31f","status":"affected","lessThan":"de4660898b7aa7e03d3b120a6bfa6b26211e4e77","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["include/linux/memcontrol.h","mm/vmscan.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"7.1","status":"affected"},{"version":"0","status":"unaffected","lessThan":"7.1","versionType":"semver"},{"version":"7.1.8","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["include/linux/memcontrol.h","mm/vmscan.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/fceb6b7f3ddec6ea9fc11577f4cf1b2da73a3101"},{"url":"https://git.kernel.org/stable/c/de4660898b7aa7e03d3b120a6bfa6b26211e4e77"}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-28T06:53:16.087Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"7.1","versionEndExcluding":"7.1.8"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"7.1","versionEndExcluding":"7.2"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}