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. ...or are you referring to the discussion about acpi_scan_lock()? I came around to agreeing with your position that documenting was better than adding superfluous locking especially because the acpi_scan_lock() is take so far away from where the device_hotplug lock is needed.
