On 8/23/18 7:23 AM, Michal Hocko wrote: > On Thu 23-08-18 07:16:34, Mikulas Patocka wrote: >> >> >> On Thu, 23 Aug 2018, Michal Hocko wrote: >> >>> On Thu 23-08-18 07:02:37, Mikulas Patocka wrote: >>> [...] >>>> This crash is not from -ENOENT. It crashes because page->compound_head is >>>> 0xffffffffffffffff (see below). >>>> >>>> If I enable CONFIG_DEBUG_VM, I also get VM_BUG. >>> >>> This smells like the struct page is not initialized properly. How is >>> this memory range added? I mean is it brought up by the memory hotplug >>> or during the boot? I believe it is due to uninitialized struct pages. Mikulas, could you please provide config file, and also the full console output. Please make sure that you have: CONFIG_DEBUG_VM=y CONFIG_ARCH_HAS_DEBUG_VIRTUAL=y I wonder what kind of struct page memory layout is used, and also if deferred struct pages are enabled or not. Have you tried bisecting the problem? Thank you, Pavel
