[openib-general] RHEL 4 U3 - lost completions

[Roland Dreier]

    Bill> At 1st, I thought that was the case, a fork, however, I do
    Bill> not think get_user_pages(), and the increment of the ref
    Bill> count, will guarantee the page struct does not change for
    Bill> RHEL 4 U3, I need to verify that though.

Are you doing a fork()?  If so then, yes, you will not be able to make
your app work on a RHEL4 kernel.  After get_user_pages(), if you do a
fork() then a copy-on-write will still happen, which will cause the
physical page to move as you have discovered.

This is fixed on newer kernels with libibverbs 1.1 (not yet released
though).  I don't think there's any real way to make it work on
RHEL4's 2.6.9 kernel.

 - R.