On Thu, 10 Oct 2019 09:17:42 +0200 David Hildenbrand <david@xxxxxxxxxx> wrote: > >> - pgmap = get_dev_pagemap(pfn, NULL); > >> - if (pgmap) > >> - return memory_failure_dev_pagemap(pfn, flags, pgmap); > >> - > >> - p = pfn_to_page(pfn); > > > > This change seems to assume that memory_failure_dev_pagemap() is never > > called for online pages. Is it an intended behavior? > > Or the concept "online pages" is not applicable to zone device pages? > > Yes, that's the real culprit. ZONE_DEVICE/devmem pages are never online > (SECTION_IS_ONLINE). The terminology "online" only applies to pages that > were given to the buddy. And as we support sup-section hotadd for > devmem, we cannot easily make use of the section flag it. I already > proposed somewhere to convert SECTION_IS_ONLINE to a subsection bitmap > and call it something like pfn_active(). > > pfn_online() would then be "pfn_active() && zone != ZONE_DEVICE". And we > could use pfn_active() everywhere to test for initialized memmaps (well, > besides some special cases like device reserved memory that does not > span full sub-sections). Until now, nobody volunteered and I have other > things to do. Is it worth a code comment or two to make this clearer?
