CVE-2026-89566

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.