CVE-2026-43115srcu: Use irq_work to start GP in tiny SRCU

Official description

In the Linux kernel, the following vulnerability has been resolved: srcu: Use irq_work to start GP in tiny SRCU Tiny SRCU's srcu_gp_start_if_needed() 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: call_srcu() [holding pi_lock] srcu_gp_start_if_needed() schedule_work() -> pool->lock workqueue_init() / create_worker() [holding pool->lock] wake_up_process() -> try_to_wake_up() -> pi_lock Also add irq_work_sync() to cleanup_srcu_struct() 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 irq_work to start process_srcu()" ]

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/28768bc7ea0b13f558a70f63cc3cfcd32d55d488
• https://git.kernel.org/stable/c/bb37286db65368cb72ba8757ad86299c4e4a73fc
• https://git.kernel.org/stable/c/a6fc88b22bc8d12ad52e8412c667ec0f5bf055af