Hello, I found out that some code does madvise(MADV_DONTNEED) on the allocated memory. I think that this unmaps the memory from the user space process. If the process touches the memory again, a COW mapping or even a new, zeroed out page is mapped in the process. Either way, the relation between the physical page, where the data from the RDMA read ends up and the virtual page is broken.
I realize that calling madvise(MADV_DONTNEED) doesn’t have any meaning for RDMA-registered memory. I feel however that my observed behavior is a bug and one of the following should happen: . madvise() on pinned memory/I/O memory should fail, i.e. return EINVAL, EIO or ENOMEM (I didn’t test what happens when you call madvise(MADV_DONTNEED) on I/O mem.) . RDMA actions on madvise()’d memory should fail. Best regards, Hannes Weisbach-- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
