On Thu, 23 Aug 2018, Pasha Tatashin wrote: > 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. I uploaded configs and console logs (for the real hardware and for the virtual machine) here: http://people.redhat.com/~mpatocka/testcases/arm64-config/ The virtual machine was running the lvm2 testsuite while the crash happened. > Have you tried bisecting the problem? I may try some old kernel in the virtual machine to test if the bug happens on it. > Thank you, > Pavel Mikulas
