CVE-2026-90182
UnknownSummary
In the Linux kernel's blk-iocost mechanism, delay state is not cleared when freeing policy data. A blk-cgroup can remain permanently marked as congested, causing readahead to be cut and throttling to be scheduled on anonymous folio allocation.
Risk Assessment
All tasks in the affected cgroup and its descendants may experience persistent I/O slowdown and memory allocation delays. This can degrade the performance of applications running in that group.
Recommendation
Update the kernel to a version containing the fix that clears the delay state in ioc_pd_free(). Until then, monitor cgroups for sustained congestion.
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- CVE-2026-100072Unknown
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Original NVD description (English source)
In the Linux kernel, the following vulnerability has been resolved: blk-iocost: clear delay state when freeing policy data iocg_kick_delay() turns sufficiently large debt into an explicit block-cgroup delay with blkcg_set_delay(), setting blkg->use_delay to -1 and incrementing blkcg->congestion_count. Clearing it again depends on iocg_kick_delay() running from the period timer, the waitq timer or the issue path. ioc_pd_free() removes the iocg from active_iocgs and cancels its waitq timer, and no further bios can arrive, so once it has run nothing is left which can reduce the debt and clear the delay. The blkcg stays marked congested for the rest of its life. blk_cgroup_congested() then returns true for every task in that cgroup and its descendants: page_cache_sync_ra() cuts readahead to a single page, page_cache_async_ra() skips it altogether, and __folio_throttle_swaprate() takes swap_avail_lock and schedules a throttle on anonymous folio allocation. Clear it explicitly, after the list removal and the synchronous hrtimer_cancel() so that neither timer processing nor an I/O path can re-arm it. The free callback can also see policy data which was never attached to a blkg, hence the pd->blkg check.
Vulnerability data from NVD (NIST) · CISA KEV · EPSS