In the Linux kernel, the following vulnerability has been resolved:
xen: privcmd: Switch from mutex to spinlock for irqfds
irqfdwakeup() gets EPOLLHUP, when it is called by eventfdrelease() by way of wakeuppoll(&ctx->wqh, EPOLLHUP), which gets called under spinlockirqsave(). We can't use a mutex here as it will lead to a deadlock.
Fix it by switching over to a spin lock.