On Thu, Jun 25, 2020 at 12:46:43PM -0700, Dan Williams wrote: >On Wed, Jun 24, 2020 at 10:53 PM David Hildenbrand <david@xxxxxxxxxx> wrote: >> >> >> >> > Am 25.06.2020 um 01:47 schrieb Dan Williams <dan.j.williams@xxxxxxxxx>: >> > >> > On Wed, Jun 24, 2020 at 3:44 PM Wei Yang >> > <richard.weiyang@xxxxxxxxxxxxxxxxx> wrote: >> > [..] >> >>> So, you are right that there is a mismatch here, but I think the >> >>> comprehensive fix is to allow early sections to be partially >> >>> depopulated/repopulated rather than have section_activate() and >> >>> section_deacticate() special case early sections. The special casing >> >>> is problematic in retrospect as section_deactivate() can't be >> >>> maintained without understand special rules in section_activate(). >> >> >> >> Hmm... This means we need to adjust pfn_valid() too, which always return true >> >> for early sections. >> > >> > Right, rather than carry workarounds in 3 locations, and the bug that >> > has resulted from then getting out of sync, just teach early section >> > mapping to allow for the subsection populate/depopulate. >> > >> >> I prefer the easy fix first - IOW what we Here here. Especially, pfn_to_online_page() will need changes as well. > >Agree, yes, let's do the simple fix first for 5.8 and the special-case >elimination work later. Dan, A quick test shows this is not a simple task. First, early sections don't set subsection bitmap, which is necessary for the hot-add/remove. To properly set subsection bitmap, we need to know how many subsections in early section. While current code doesn't has a alignment requirement for last early section. We mark the whole last early section as present. I don't find a way to enable this. -- Wei Yang Help you, Help me
