Description
In the Linux kernel, the following vulnerability has been resolved:
dm cache: fix issue with background work locking
dm cache used a rw_semaphore for background_work_lock. Write locks on
rw_semaphores have strict owner semantics, but there was no guarantee
that the process that locked background_work_lock was the same process
that unlocked it. This can be easily seen using a kernel compiled with
CONFIG_DEBUG_RWSEMS. Given a dm cache device <cache>, run: 'dmsetup
suspend <cache> && dmsetup resume <cache>'. This will trigger a kernel
warning:
DEBUG_RWSEMS_WARN_ON((rwsem_owner(sem) != current) && !rwsem_test_oflags(sem, RWSEM_NONSPINNABLE))
triggered by cache_resume(). To fix this, switch from a rw_semaphore to
a spinlock and a wait queue. dm cache already has a wait queue and
associated counter, migration_wait and nr_allocated_migrations, that was
getting woken up when background work was getting completed, but wasn't
actually used by anything. This is replaced by the background_work queue
and counter.
dm cache: fix issue with background work locking
dm cache used a rw_semaphore for background_work_lock. Write locks on
rw_semaphores have strict owner semantics, but there was no guarantee
that the process that locked background_work_lock was the same process
that unlocked it. This can be easily seen using a kernel compiled with
CONFIG_DEBUG_RWSEMS. Given a dm cache device <cache>, run: 'dmsetup
suspend <cache> && dmsetup resume <cache>'. This will trigger a kernel
warning:
DEBUG_RWSEMS_WARN_ON((rwsem_owner(sem) != current) && !rwsem_test_oflags(sem, RWSEM_NONSPINNABLE))
triggered by cache_resume(). To fix this, switch from a rw_semaphore to
a spinlock and a wait queue. dm cache already has a wait queue and
associated counter, migration_wait and nr_allocated_migrations, that was
getting woken up when background work was getting completed, but wasn't
actually used by anything. This is replaced by the background_work queue
and counter.
Published:
2026-11-03
Score:
n/a
EPSS:
n/a
KEV:
No
Impact:
n/a
Action:
n/a
Analysis
No analysis available yet.
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
| Vendor | Product | Default status | Versions | |||||||||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Linux | Linux | unaffected |
|
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| Linux | Linux | affected |
|
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No data available yet.
Remediation
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Tracking
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Advisories
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References
History
Tue, 03 Nov 2026 11:30:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | In the Linux kernel, the following vulnerability has been resolved: dm cache: fix issue with background work locking dm cache used a rw_semaphore for background_work_lock. Write locks on rw_semaphores have strict owner semantics, but there was no guarantee that the process that locked background_work_lock was the same process that unlocked it. This can be easily seen using a kernel compiled with CONFIG_DEBUG_RWSEMS. Given a dm cache device <cache>, run: 'dmsetup suspend <cache> && dmsetup resume <cache>'. This will trigger a kernel warning: DEBUG_RWSEMS_WARN_ON((rwsem_owner(sem) != current) && !rwsem_test_oflags(sem, RWSEM_NONSPINNABLE)) triggered by cache_resume(). To fix this, switch from a rw_semaphore to a spinlock and a wait queue. dm cache already has a wait queue and associated counter, migration_wait and nr_allocated_migrations, that was getting woken up when background work was getting completed, but wasn't actually used by anything. This is replaced by the background_work queue and counter. | |
| Title | dm cache: fix issue with background work locking | |
| First Time appeared |
Linux
Linux linux Kernel |
|
| CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Linux
Linux linux Kernel |
|
| References |
|
|
MITRE
Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2026-11-03T11:40:45.109Z
Reserved: 2026-09-25T10:25:14.404Z
Link: CVE-2026-99256
Vulnrichment
No data.
NVD
No data.
Redhat
No data.
OpenCVE Enrichment
No data.
Weaknesses
No weakness.