CVE-2026-23168 – flex_proportions: make fprop_new_period() hardirq safe

CVE ID : CVE-2026-23168

Published : Feb. 14, 2026, 4:15 p.m. | 14 minutes ago

Description : In the Linux kernel, the following vulnerability has been resolved:

flex_proportions: make fprop_new_period() hardirq safe

Bernd has reported a lockdep splat from flexible proportions code that is
essentially complaining about the following race:

run_timer_softirq – we are in softirq context
call_timer_fn
writeout_period
fprop_new_period
write_seqcount_begin(&p->sequence);

…
blk_mq_end_request()
blk_update_request()
ext4_end_bio()
folio_end_writeback()
__wb_writeout_add()
__fprop_add_percpu_max()
if (unlikely(max_frac sequence);
– sees odd sequence so loops indefinitely

Note that a deadlock like this is only possible if the bdi has configured
maximum fraction of writeout throughput which is very rare in general but
frequent for example for FUSE bdis. To fix this problem we have to make
sure write section of the sequence counter is irqsafe.

Severity: 0.0 | NA

Visit the link for more details, such as CVSS details, affected products, timeline, and more…