search for: page_extant

This is netback multithread support patchset version 4. Main Changes from v3: 1. Patchset is against xen/next tree. 2. Merge group and idx into netif->mapping. 3. Use vmalloc to allocate netbk structures. Main Changes from v2: 1. Merge "group" and "idx" into "netif->mapping", therefore page_ext is not used now. 2. Put netbk_add_netif() and netbk_remove_netif()

ging_prep ensures that an mfn is backing the paged-out gfn, and transitions to the next state in the paging state machine for this page. Foreign mappings of the gfn will now succeed. This is the key idea, as it allows the pager to now map the gfn and fill in its contents. Unfortunately, it also allows any other foreign mapper to map the gfn and read its contents. This is particularly dangerous

When counting required slots for skb, netback directly uses DIV_ROUND_UP to get slots required by header data. This is wrong when offset in the page of header data is not zero, and is also inconsistent with following calculation for required slot in netbk_gop_skb. In netbk_gop_skb, required slots are calculated based on offset and len in page of header data. It is possible that required slots