On 05.01.21 08:44, Michal Hocko wrote: > On Mon 04-01-21 17:30:48, David Hildenbrand wrote: >>>> Let's assume this is indeed a reserved pfn in the altmap. What's the >>>> actual address of the memmap? >>> >>> Not sure what exactly you are asking for but crash says >>> crash> kmem -p 6060000 >>> PAGE PHYSICAL MAPPING INDEX CNT FLAGS >>> fffff8c600181800 6060000 0 0 0 fffffc0000000 >> >> ^ this looks like it was somewhat initialized. All flags zero, nid/zone >> set to -1 (wild guess) and thus the crash? weird > > Yes that made me scratch my head as well. My best guess would be that this is indeed part of the altmap reserve with a memmap on the altmap. Maybe these values are just leftovers on the PMEM device (e.g., from older kernels)? In the kernel, I cannot find anything that would initialize node/zone to -1 only. @Dan: Will get_dev_pagemap() return a valid dev_pagemap for pfns falling into the altmap reserved region? I think we should also initialize the memmap of the altmap reserved region somewhow. -- Thanks, David / dhildenb
