On 24.01.20 19:04, Dan Williams wrote: > On Fri, Jan 24, 2020 at 4:56 AM Michal Hocko <mhocko@xxxxxxxxxx> wrote: >> >> On Fri 10-01-20 13:27:24, Dan Williams wrote: >>> On Fri, Jan 10, 2020 at 9:42 AM David Hildenbrand <david@xxxxxxxxxx> wrote: >> [...] >>>> For your reference (roughly 5 months ago, so not that old) >>>> >>>> https://lkml.kernel.org/r/20190724143017.12841-1-david@xxxxxxxxxx >>> >>> Oh, now I see the problem. You need to add that lock so far away from >>> the __add_memory() to avoid lock inversion problems with the >>> acpi_scan_lock. The organization I was envisioning would not work >>> without deeper refactoring. >> >> Sorry to come back to this late. Has this been resolved? > > The mem_hotplug_lock lockdep splat fix in this patch has not landed. > David and I have not quite come to consensus on how to resolve online > racing removal. IIUC David wants that invalidation to be > pages_correctly_probed(), I would prefer it to be directly tied to the > object, struct memory_block, that remove_memory_block_devices() has > modified, mem->section_count = 0. FWIW, there is no such race possible - esp. zombie devices (see https://lore.kernel.org/lkml/1580c2bb-5e94-121d-8153-c8a7230b764b@xxxxxxxxxx/). (I'm planning to send a patch to remove mem->section_count soon) -- Thanks, David / dhildenb
