We received several reports about applications (IOR and other unrelated user-provided programs) started from Lustre receiving SIGBUS signals.

We were able to reproduce the issue with IOR, RHEL7 kernel on the client.

It seems that it is caused by LU-14541 and the mechanics is the following:

1) a major fault in the IOR code happens

2) ll_fault()>...>filemap_fault()

3) ll_readpage() is issued from filemap_fault()

4) wait_on_page_locked() is issued from filemap_fault()

5) the uptodate check in filemap_fault() fails due to a parallel ClearPageUptodate() called from a blocking AST handler

6) VM_FAULT_SIGBUS is returned