On 01/16/20 at 09:14am, David Hildenbrand wrote: > On 16.01.20 09:06, David Hildenbrand wrote: > > On 16.01.20 04:01, Pingfan Liu wrote: > >> When fully deactivated, it is meaningless to keep the value of a section's > >> mem_map. And its mem_map will be reassigned during re-added. > >> > >> Beside this, it breaks the user space tool "makedumpfile", which makes > >> assumption that a hot-removed section having mem_map as NULL. > >> > >> The bug can be reproduced on IBM POWERVM by "drmgr -c mem -r -q 5" , > >> trigger a crash, and save vmcore by makedumpfile > > > > Are you using an up-to-date makedumfile and did kdump.service properly > > get reloaded on the udev events? I remember that this works. > > > > makedumpfile will not dump memory sections that a) are not marked > > offline (SECTION_IS_ONLINE) - after offlining b) are not part of an > > iomem resource - after memory unplug. Makedumpfile seems to only check SECTION_MARKED_PRESENT. Then the NULL memmap will fail vmcore dumping, I guess. > > > > > > The current code makes sure that sparse_decode_mem_map() will return NULL. > > > > ... but it's only used at this very place. I think we should add a > Fixes: tag, although this might be fixed as well in makedumpfile (so > people are aware that patch broke something) Agree, it's worth fixing it too in makedumpfile side to enhance.
