CVE-2026-89757
mm/mglru: fix and remove redundant unevictable folio handling
- Published
- Updated
- Reserved
- Assigned by
- Linux
Description
In the Linux kernel, the following vulnerability has been resolved: mm/mglru: fix and remove redundant unevictable folio handling sort_folio() has a shortcut for moving folios that are no longer evictable but are still sitting on a generation list. However, this shortcut is buggy. It does not follow the PG_lru usage convention, and it has a more serious issue. Unevictable folios are not threaded on lists[LRU_UNEVICTABLE], so that folio->lru can be reused to hold folio->mlock_count (see the comment in lruvec_init()). Hence lruvec_add_folio() skips the list_add() for them, and every other place that turns a folio unevictable initialises mlock_count explicitly: lru_add() sets it to 0, __mlock_folio() and __mlock_new_folio() set it to !!folio_test_mlocked(folio). sort_folio() sets nothing, and the lru_gen_del_folio() right above it may have already poisoned folio->lru via list_del(), so mlock_count ends up aliasing LIST_POISON2, which reads as 0x122, i.e. 290. The result is user visible. On munlock, __munlock_folio() decrements that bogus count, finds it still non-zero and bails out before clearing PG_mlocked, so the folio remains unevictable and the Mlocked accounting stays inflated until the folio is freed. The shortcut also touches the LRU flags in the wrong order. It calls lru_gen_del_folio() while PG_lru is still set, so a concurrent folio_test_clear_lru() (e.g. compaction, folio_isolate_lru()) can succeed on a folio that has already been taken off the generation list, which may lead to unexpected behavior. So fix it by isolating them as common folios and letting the generic shrink path cull them. This matches the classical LRU behavior, and there should be no visible effect on the generic eviction or isolation behavior. There is no performance concern either, such a folio goes through this once, and then it is off the generation lists for good.
Timeline
ID reserved
By Linux
Published
- 49 days later
· 49 days later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
No CVSS score yet: neither the CNA, CISA nor NVD has scored this CVE. NVD status: Received.
- EPSS (exploitation in 30 days)
- 0.21% · top 89% of all CVEs (8 Nov 2026)
The list uses the assigner's score when there is one, then CISA's, then NVD's: Not scored.
Affected products
- affected ac35a490237446b71e3b4b782b1596967edd0aa8 – < e9f2160081a1e3ebb285bd71be3382abaeb8390a
- affected ac35a490237446b71e3b4b782b1596967edd0aa8 – < b1d7c69e6c7d3ec47513b911ce7529e56d183dad
- affected ac35a490237446b71e3b4b782b1596967edd0aa8 – < 49193dac48d30eee2a21da88a7262d52a7feefae
- affected ac35a490237446b71e3b4b782b1596967edd0aa8 – < 54a58d6656dd403b686b247f0bad8507cbfb45df
- affected ac35a490237446b71e3b4b782b1596967edd0aa8 – < 15d3a2a71c8bf7333d019d249ee33669e69e4275
- affected ac35a490237446b71e3b4b782b1596967edd0aa8 – < f7e698e326b239a91ea15844817551921209e826
- affected 6.1
- unaffected < 6.1
- unaffected 6.1.191 – ≤ 6.1.*
- unaffected 6.6.160 – ≤ 6.6.*
- unaffected 6.12.114 – ≤ 6.12.*
- unaffected 6.18.51 – ≤ 6.18.*
- unaffected 7.2.4 – ≤ 7.2.*
- unaffected 7.3 – ≤ *
References (6)
- https://git.kernel.org/stable/c/e9f2160081a1e3ebb285bd71be3382abaeb8390a (opens in a new tab)
- https://git.kernel.org/stable/c/b1d7c69e6c7d3ec47513b911ce7529e56d183dad (opens in a new tab)
- https://git.kernel.org/stable/c/49193dac48d30eee2a21da88a7262d52a7feefae (opens in a new tab)
- https://git.kernel.org/stable/c/54a58d6656dd403b686b247f0bad8507cbfb45df (opens in a new tab)
- https://git.kernel.org/stable/c/15d3a2a71c8bf7333d019d249ee33669e69e4275 (opens in a new tab)
- https://git.kernel.org/stable/c/f7e698e326b239a91ea15844817551921209e826 (opens in a new tab)
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
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[](https://cveledger.app/cve/CVE-2026-89757)Record last updated .