On Thu 01-03-18 16:09:35, Daniel Vacek wrote: [...] > $ grep 7b7ff000 /proc/iomem > 7b7ff000-7b7fffff : System RAM [...] > After commit b92df1de5d28 machine eventually crashes with: > > BUG at mm/page_alloc.c:1913 > > > VM_BUG_ON(page_zone(start_page) != page_zone(end_page));
This is an important information that should be in the changelog. > >From registers and stack I digged start_page points to > ffffe31d01ed8000 (note that this is > page ffffe31d01edffc0 aligned to pageblock) and I can see this in memory dump: > > crash> kmem -p 77fff000 78000000 7b5ff000 7b600000 7b7fe000 7b7ff000 > 7b800000 7ffff000 80000000 > PAGE PHYSICAL MAPPING INDEX CNT FLAGS > ffffe31d01e00000 78000000 0 0 0 0 > ffffe31d01ed7fc0 7b5ff000 0 0 0 0 > ffffe31d01ed8000 7b600000 0 0 0 0 <<<< note Are those ranges covered by the System RAM as well? > that nodeid and zonenr are encoded in top bits of page flags which are > not initialized here, hence the crash :-( > ffffe31d01edff80 7b7fe000 0 0 0 0 > ffffe31d01edffc0 7b7ff000 0 0 1 1fffff00000000 > ffffe31d01ee0000 7b800000 0 0 1 1fffff00000000 > ffffe31d01ffffc0 7ffff000 0 0 1 1fffff00000000 It is still not clear why not to do the alignment in memblock_next_valid_pfn rahter than its caller. -- Michal Hocko SUSE Labs
