# CVE-2026-64100: linux: In the Linux kernel, the following vulnerability has been resolved:  drm/msm: Fix shrinker deadlock  With PROVE_LOCKI...

CVE-2026-64100 is fixed in linux on 1 platform by DEBIAN-CVE-2026-64100 (version 7.0.12-1), released July 20, 2026. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2026-64100
- Priority: Routine
- CVSS: 5.5 (medium)
- EPSS: 0.0012
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Jul 19, 2026

## 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---

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | linux Debian 14 | 7.0.12-1 | [DEBIAN-CVE-2026-64100](https://patchblox.com/security/data/fix/linux/debian-cve-2026-64100.md) | Jul 20, 2026 |

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