CVE-2026-89753 in Linux
Summary
by MITRE • 09/11/2026
In the Linux kernel, the following vulnerability has been resolved:
mm/vmscan: report RCU-tasks quiescent states in shrink_lruvec()
I am seeing some rcu_tasks stalls in the Meta fleet during reclaim.
INFO: rcu_tasks detected stalls on tasks: 0000000088620d09: .. nvcsw: 6735/6735 holdout: 1 idle_cpu: -1/8 task:GlobalCPUThread state:R running task pid:2552016 tgid:2524552 Call Trace: shrink_lruvec mem_cgroup_iter shrink_node do_try_to_free_pages try_to_free_pages __alloc_frozen_pages_noprof alloc_pages_noprof pte_alloc_one __pte_alloc handle_mm_fault
Nothing promises direct reclaim returns in bounded time, and the scan loop in shrink_lruvec() only calls cond_resched(), which is a no-op on PREEMPTION kernels. Involuntary preemption is not a Tasks-RCU quiescent state, so the reclaiming task never reports one and becomes a holdout.
Upgrade it to cond_resched_tasks_rcu_qs(), which reports a quiescent state even when cond_resched() does nothing.
PS: This has been discussed in [1]
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