Comment 13 for bug 1505948

Interesting that implies that we submitted some kind of async IO, and the IO must have completed and free(io). This implies that the io->req count is getting out of sync with the world. A quick eyeball says we are handling them right, but something is exploding. To try and confirm this is correct I have built a test kernel with a debugging patch applied. This bumps the io->req from 1 (the pending report for the submission of the IO) to 100. If the theory is right the io->req should go to 99 or fewer. If that occurs we should be able to detect it and report the type of the IO in flight. I also have tried to correct for it in the case where that is possible.

Would you be able to test the kernel at the below URL and let me know what you see in dmesg. If the detection triggers we should see "fuse_direct_IO: io->reg would have gone negative" messages, and I would be interested in the content of those when it occurs:

    http://people.canonical.com/~apw/lp1505948-wily/

Builds will be there shortly. Please report any results back here.