On Tue, Jan 21, 2025 at 06:30:53PM -0800, Josh Poimboeuf wrote: > It's possible for irq_work_queue() to fail if the work has already been > claimed. That can happen if a TWA_NMI_CURRENT task work is requested > before a previous TWA_NMI_CURRENT IRQ work on the same CPU has gotten a > chance to run.
I'm confused, if it fails then it's already pending, and we'll get the notification already. You can still add the work. > The error has to be checked before the write to task->task_works. Also > the try_cmpxchg() loop isn't needed in NMI context. The TWA_NMI_CURRENT > case really is special, keep things simple by keeping its code all > together in one place. NMIs can nest, consider #DB (which is NMI like) doing task_work_add() and getting interrupted with NMI doing the same. Might all this be fallout from trying to fix that schedule() bug from the next patch, because as is, I don't see it.
