On Wed 07-11-18 09:50:10, Vlastimil Babka wrote: > On 11/7/18 8:02 AM, Konstantin Khlebnikov wrote: [...] > > Could you point what exactly are you fixing with this set? > > > > from v2: > > > > > totalram_pages, zone->managed_pages and totalhigh_pages updates > > > are protected by managed_page_count_lock, but readers never care > > > about it. Convert these variables to atomic to avoid readers > > > potentially seeing a store tear. > > > > This? > > > > > > Aligned unsigned long almost always stored at once. > > The point is "almost always", so better not rely on it :) But the main > motivation was that managed_page_count_lock handling was complicating > Arun's "memory_hotplug: Free pages as higher order" patch and it seemed > a better idea to just remove and convert this to atomics, with > preventing potential store-to-read tearing as a bonus. And more importantly the lock itself seems bogus as mentioned here http://lkml.kernel.org/r/20181106141732.GR27423@xxxxxxxxxxxxxx > It would be nice to mention it in the changelogs though. agreed -- Michal Hocko SUSE Labs
