CVE-2026-64415

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Softlockup in Linux Kernel Memory Swap Reclaim

Publication date: 2026-07-25

Last updated on: 2026-08-11

Assigner: kernel.org

Description

In the Linux kernel, the following vulnerability has been resolved: mm/swap: add cond_resched() in swap_reclaim_full_clusters to prevent softlockup We hit a real softlockup in an internal stress test environment. The workload was LTP memory/swap stress on a large arm64 machine, with 320 CPUs, about 1TB memory and an 8.6GB swap device. The system was under heavy load and the swap device had a large number of full clusters. The softlockup was triggered during a stress test after about 3 days. So, add periodic cond_resched() calls during large full_clusters reclaim operations to prevent softlockup issues. Detailed call trace as follow: PID: 3817773 TASK: ffff0883bb28b780 CPU: 48 COMMAND: "kworker/48:7" #0 [ffff800080183d10] __crash_kexec at ffffa4c1361e5de4 #1 [ffff800080183d90] panic at ffffa4c1360d5e9c #2 [ffff800080183e20] watchdog_timer_fn at ffffa4c136231fa8 ... #16 [ffff8000c4ad3cb0] swap_cache_del_folio at ffffa4c1363e1614 #17 [ffff8000c4ad3ce0] __try_to_reclaim_swap at ffffa4c1363e4bfc #18 [ffff8000c4ad3d40] swap_reclaim_full_clusters at ffffa4c1363e5474 #19 [ffff8000c4ad3da0] swap_reclaim_work at ffffa4c1363e550c #20 [ffff8000c4ad3dc0] process_one_work at ffffa4c136102edc #21 [ffff8000c4ad3e10] worker_thread at ffffa4c136103398 #22 [ffff8000c4ad3e70] kthread at ffffa4c13610d95c

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Meta Information

Published

2026-07-25

Last Modified

2026-08-11

Generated

2026-08-14

AI Q&A

2026-07-25

EPSS Evaluated

2026-08-13

NVD

CVE-2026-64415

EUVD

EUVD-2026-48959

Affected Vendors & Products

Vendor	Product	Version / Range
linux	linux_kernel	*

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-UNKNOWN

Attack-Flow Graph

Executive Summary

This vulnerability is a softlockup issue in the Linux kernel's memory management subsystem. It occurs during swap reclaim operations when the system is under heavy load, particularly when dealing with a large number of full swap clusters. The kernel fails to yield CPU time periodically, causing the system to appear unresponsive.

Detection Guidance

This vulnerability is specific to the Linux kernel's memory management during swap operations. Detection involves monitoring for softlockups in kernel logs. Check for messages like 'watchdog: BUG: soft lockup - CPU#X stuck for Ns!' in /var/log/kern.log or dmesg output. No specific commands are provided in the context to directly detect this issue.

Impact Analysis

This vulnerability can cause system hangs or crashes during heavy memory and swap operations. It may lead to degraded performance, unresponsive systems, or even kernel panics in extreme cases, especially on high-CPU-count systems with large memory and swap configurations.

Compliance Impact

This vulnerability does not directly affect compliance with standards like GDPR or HIPAA. It is a softlockup issue in the Linux kernel's memory management during swap operations, which could lead to system unavailability but does not inherently involve data breaches or unauthorized access.

Mitigation Strategies

Upgrade the Linux kernel to a version that includes the fix for this vulnerability. The context indicates the issue was resolved by adding cond_resched() calls in swap_reclaim_full_clusters. Apply kernel updates from your distribution vendor immediately.

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