On Wed, Sep 20, 2017 at 11:29:31AM +0200, Michal Hocko wrote: > Hi, > I am currently at a conference so I will most probably get to this next > week but I will try to ASAP. > > On Tue 19-09-17 11:41:14, Seth Forshee wrote: > > Hi Michal, > > > > I'm seeing oopses in various locations when hotplugging memory in an x86 > > vm while running a 32-bit kernel. The config I'm using is attached. To > > reproduce I'm using kvm with the memory options "-m > > size=512M,slots=3,maxmem=2G". Then in the qemu monitor I run: > > > > object_add memory-backend-ram,id=mem1,size=512M > > device_add pc-dimm,id=dimm1,memdev=mem1 > > > > Not long after that I'll see an oops, not always in the same location > > but most often in wp_page_copy, like this one: > > This is rather surprising. How do you online the memory? The kernel has CONFIG_MEMORY_HOTPLUG_DEFAULT_ONLINE=y. > > [ 24.673623] BUG: unable to handle kernel paging request at dffff000 > > [ 24.675569] IP: wp_page_copy+0xa8/0x660 > > could you resolve the IP into the source line? It seems I don't have that kernel anymore, but I've got a 4.14-rc1 build and the problem still occurs there. It's pointing to the call to __builtin_memcpy in memcpy (include/linux/string.h line 340), which we get to via wp_page_copy -> cow_user_page -> copy_user_highpage. Thanks, Seth -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
