CVE-2026-43115

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

srcu: Use irq_work to start GP in tiny SRCU

Tiny SRCU's srcugpstartifneeded() directly calls schedule_work(), which acquires the workqueue pool->lock.

This causes a lockdep splat when call_srcu() is called with a scheduler lock held, due to:

callsrcu() [holding pilock] srcugpstartifneeded() schedule_work() -> pool->lock

workqueueinit() / createworker() [holding pool->lock] wakeupprocess() -> trytowakeup() -> pilock

Also add irqworksync() to cleanupsrcustruct() to prevent a use-after-free if a queued irq_work fires after cleanup begins.

Tested with rcutorture SRCU-T and no lockdep warnings.

[ Thanks to Boqun for similar fix in patch "rcu: Use an intermediate irqwork to start processsrcu()" ]