CVE-2026-89566: jbd2: check need_resched() when skipping busy checkpoint buffers

Severity: unknown
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-09-11 · updated 2026-10-21

Description

In the Linux kernel, the following vulnerability has been resolved: jbd2: check need_resched() when skipping busy checkpoint buffers journal_shrink_one_cp_list() skips busy checkpoint buffers when called with JBD2_SHRINK_BUSY_SKIP. The continue statement on this path also skips the need_resched() check at the end of the loop body. Consequently, when a checkpoint list contains mostly busy buffers, the shrinker can walk the entire list while holding journal->j_list_lock, even when a reschedule has been requested. Large checkpoint lists under memory pressure can therefore cause long lock hold times and leave other CPUs spinning on j_list_lock, resulting in soft lockups or RCU stalls. Route the busy-buffer path through the need_resched() check so that the shrinker can release j_list_lock and reschedule promptly, restoring parity with the clean-buffer path, which already checks need_resched(). This does not change which checkpoint buffers are eligible for removal.

Affected products

Linux kernel: from 5.15.129 before 5.16; from 6.1.50 before 6.2; from 6.4.13 before 6.5; 6.5 — fixed in 5.16, 6.2, 6.5, 7.3

How to fix

Upgrade to a fixed version: Linux kernel 5.16, 6.2, 6.5, 7.3. Check the vendor advisory for mitigations.

References

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