# CVE-2026-64100: drm/msm: Fix shrinker deadlock > A deadlock in the Linux kernel MSM DRM driver can cause a system hang under memory pressure, requiring a kernel patch to resolve. - **Severity:** Medium 5.5 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H`) - **Exploited in the wild:** Not known - **Login needed:** Any signed-in user - **Attackable:** Local or same network only - **Victim action needed:** Not needed - **Fix available:** Yes - **Published:** 19 Jul 2026 - **Updated:** 19 Jul 2026 - **Also known as:** BELL-CVE-2026-64100, DEBIAN-CVE-2026-64100, GHSA-3q3c-q46p-rwcg, UBUNTU-CVE-2026-64100 ## What is CVE-2026-64100? CVE-2026-64100 is a medium-severity vulnerability in Linux kernel, published on 19 Jul 2026. It can only be exploited from the same machine or local network, with no action from the victim. ### Official description In the Linux kernel, the following vulnerability has been resolved: drm/msm: Fix shrinker deadlock With PROVE_LOCKING on an Snapdragon X1 and VM reclaim pressure, we see: ====================================================== WARNING: possible circular locking dependency detected 7.0.0-debug+ #43 Tainted: G W ------------------------------------------------------ kswapd0/82 is trying to acquire lock: ffff800080ec3870 (reservation_ww_class_acquire){+.+.}-{0:0}, at: msm_gem_shrinker_scan+0x17c/0x400 [msm] but task is already holding lock: ffffc31709b263b8 (fs_reclaim){+.+.}-{0:0}, at: balance_pgdat+0x88/0x988 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (fs_reclaim){+.+.}-{0:0}: __lock_acquire+0x4d0/0xad0 lock_acquire.part.0+0xc4/0x248 lock_acquire+0x8c/0x248 fs_reclaim_acquire+0xd0/0xf0 dma_resv_lockdep+0x224/0x348 do_one_initcall+0x84/0x5d0 do_initcalls+0x194/0x1d8 kernel_init_freeable+0x128/0x180 kernel_init+0x2c/0x160 ret_from_fork+0x10/0x20 -> #1 (reservation_ww_class_mutex){+.+.}-{4:4}: __lock_acquire+0x4d0/0xad0 lock_acquire.part.0+0xc4/0x248 lock_acquire+0x8c/0x248 dma_resv_lockdep+0x1a8/0x348 do_one_initcall+0x84/0x5d0 do_initcalls+0x194/0x1d8 kernel_init_freeable+0x128/0x180 kernel_init+0x2c/0x160 ret_from_fork+0x10/0x20 -> #0 (reservation_ww_class_acquire){+.+.}-{0:0}: check_prev_add+0x114/0x790 validate_chain+0x594/0x6f0 __lock_acquire+0x4d0/0xad0 lock_acquire.part.0+0xc4/0x248 lock_acquire+0x8c/0x248 drm_gem_lru_scan+0x1ac/0x440 msm_gem_shrinker_scan+0x17c/0x400 [msm] do_shrink_slab+0x150/0x4a0 shrink_slab+0x144/0x460 shrink_one+0x9c/0x1b0 shrink_many+0x27c/0x5c0 shrink_node+0x344/0x550 balance_pgdat+0x2c0/0x988 kswapd+0x11c/0x318 kthread+0x10c/0x128 ret_from_fork+0x10/0x20 other info that might help us debug this: Chain exists of: reservation_ww_class_acquire --> reservation_ww_class_mutex --> fs_reclaim Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(fs_reclaim); lock(reservation_ww_class_mutex); lock(fs_reclaim); lock(reservation_ww_class_acquire); *** DEADLOCK *** 1 lock held by kswapd0/82: #0: ffffc31709b263b8 (fs_reclaim){+.+.}-{0:0}, at: balance_pgdat+0x88/0x988 stack backtrace: CPU: 4 UID: 0 PID: 82 Comm: kswapd0 Tainted: G W 7.0.0-debug+ #43 PREEMPT(full) Tainted: [W]=WARN Hardware name: LENOVO 21BX0016US/21BX0016US, BIOS N3HET94W (1.66 ) 09/15/2025 Call trace: show_stack+0x20/0x40 (C) dump_stack_lvl+0x9c/0xd0 dump_stack+0x18/0x30 print_circular_bug+0x114/0x120 check_noncircular+0x178/0x198 check_prev_add+0x114/0x790 validate_chain+0x594/0x6f0 __lock_acquire+0x4d0/0xad0 lock_acquire.part.0+0xc4/0x248 lock_acquire+0x8c/0x248 drm_gem_lru_scan+0x1ac/0x440 msm_gem_shrinker_scan+0x17c/0x400 [msm] do_shrink_slab+0x150/0x4a0 shrink_slab+0x144/0x460 shrink_one+0x9c/0x1b0 shrink_many+0x27c/0x5c0 shrink_node+0x344/0x550 balance_pgdat+0x2c0/0x988 kswapd+0x11c/0x318 kthread+0x10c/0x128 ret_from_fork+0x10/0x20 kswapd0 holding fs_reclaim calls the MSM shrinker, which calls dma_resv_lock. This in turn acquires fs_reclaim. Fix this deadlock by using dma_resv_trylock() instead, dropping the subsequently unused passed wait-wound lock 'ticket'. Patchwork: https://patchwork.freedesktop.org/patch/723564/ [rob: fixup compile errors, replace lockdep splat with somethin ---truncated--- Weakness: CWE-667 (Improper Locking) ## Which versions are affected by CVE-2026-64100? It affects 1 product. Products: Linux kernel. ## How do I fix CVE-2026-64100? Apply the vendor's patch. ## Is CVE-2026-64100 being exploited? There is no known exploitation of CVE-2026-64100 in the wild and no public exploit code. ## Other vulnerabilities in Linux kernel - [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild) - [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild) - [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild) - [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild) - [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild) ## Fix prompt for AI coding agents ```text Check this codebase for CVE-2026-64100 and fix it if it is affected. What it is: CVE-2026-64100 is a medium-severity vulnerability in Linux kernel, published on 19 Jul 2026. It can only be exploited from the same machine or local network, with no action from the victim. Exploitation: There is no known exploitation of CVE-2026-64100 in the wild and no public exploit code. Affected product: Linux kernel. No package-level version data is available, so check the vendor advisory linked from the reference page. Task: 1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies. 2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it. 3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead. 4. Run the tests and summarise what changed and why. 5. If nothing in the project is affected, say so and change nothing. Reference: https://insights.sbomify.com/CVE-2026-64100/ (Markdown: https://insights.sbomify.com/CVE-2026-64100/index.md) ``` ## Sources - CVE record: https://www.cve.org/CVERecord?id=CVE-2026-64100 - NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-64100 - OSV: https://osv.dev/vulnerability/CVE-2026-64100 --- From sbomify Insights: https://insights.sbomify.com/CVE-2026-64100/ Summaries are generated and may contain mistakes; the official description above is the record.