On Tue, Jan 14, 2020 at 05:12:13PM +0100, Christoph Hellwig wrote: > Second I/O > completions often come from interrupt context, which means the re-acquire > is recorded as from irq context, leading to warnings about incorrect > contexts. I wonder if we could just have a bit in lockdep that says > returning to userspace is ok for this particular lock? That would also > clean up the fsfreeze situation a lot.
It would be helpful if we could also use the same lockdep logic for PageLocked. Again, it's a case where returning to userspace with PageLock held is fine, because we're expecting an interrupt to come in and drop the lock for us. Perhaps the right answer is, from lockdep's point of view, to mark the lock as being released at the point where we submit the I/O. Then in the completion path release the lock without telling lockdep we released it. That would catch cases where we inadvertently returned to userspace without submitting the I/O, for example.