mirror of
https://github.com/torvalds/linux.git
synced 2026-10-07 22:37:45 -04:00
David Hildenbrand
6cc26d7761
Let's properly use page_offline_(start|end) to synchronize setting PageOffline(), so we won't have valid page access to unplugged memory regions from /proc/kcore. Existing balloon implementations usually allow reading inflated memory; doing so might result in unnecessary overhead in the hypervisor, which is currently the case with virtio-mem. For future virtio-mem use cases, it will be different when using shmem, huge pages, !anonymous private mappings, ... as backing storage for a VM. virtio-mem unplugged memory must no longer be accessed and access might result in undefined behavior. There will be a virtio spec extension to document this change, including a new feature flag indicating the changed behavior. We really don't want to race against PFN walkers reading random page content. Link: https://lkml.kernel.org/r/[email protected] Signed-off-by: David Hildenbrand <[email protected]> Acked-by: Michael S. Tsirkin <[email protected]> Acked-by: Mike Rapoport <[email protected]> Reviewed-by: Oscar Salvador <[email protected]> Cc: Aili Yao <[email protected]> Cc: Alexey Dobriyan <[email protected]> Cc: Alex Shi <[email protected]> Cc: Haiyang Zhang <[email protected]> Cc: Jason Wang <[email protected]> Cc: Jiri Bohac <[email protected]> Cc: "K. Y. Srinivasan" <[email protected]> Cc: "Matthew Wilcox (Oracle)" <[email protected]> Cc: Michal Hocko <[email protected]> Cc: Mike Kravetz <[email protected]> Cc: Naoya Horiguchi <[email protected]> Cc: Roman Gushchin <[email protected]> Cc: Stephen Hemminger <[email protected]> Cc: Steven Price <[email protected]> Cc: Wei Liu <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>