On Tue 04-04-17 16:43:39, Reza Arbab wrote: > On Tue, Apr 04, 2017 at 09:41:22PM +0200, Michal Hocko wrote: > >On Tue 04-04-17 13:30:13, Reza Arbab wrote: > >>I think I found another edge case. You > >>get an oops when removing all of a node's memory: > >> > >>__nr_to_section > >>__pfn_to_section > >>find_biggest_section_pfn > >>shrink_pgdat_span > >>__remove_zone > >>__remove_section > >>__remove_pages > >>arch_remove_memory > >>remove_memory > > > >Is this something new or an old issue? I believe the state after the > >online should be the same as before. So if you onlined the full node > >then there shouldn't be any difference. Let me have a look... > > It's new. Without this patchset, I can repeatedly > add_memory()->online_movable->offline->remove_memory() all of a node's > memory. This is quite unexpected because the code obviously cannot handle the first memory section. Could you paste /proc/zoneinfo and grep . -r /sys/devices/system/memory/auto_online_blocks/memory*, after onlining for both patched and unpatched kernels? > >From 1b08ecef3e8ebcef585fe8f2b23155be54cce335 Mon Sep 17 00:00:00 2001 > >From: Michal Hocko <mhocko@xxxxxxxx> > >Date: Tue, 4 Apr 2017 21:09:00 +0200 > >Subject: [PATCH] mm, hotplug: get rid of zone/node shrinking > > > ...%<... > >--- > >mm/memory_hotplug.c | 207 ---------------------------------------------------- > >1 file changed, 207 deletions(-) > > Okay, getting further. With this I can again repeatedly add and remove, but > now I'm seeing a weird variation of that earlier issue: > > 1. add_memory(), online_movable > /sys/devices/system/node/nodeX/memoryY symlinks are created. > > 2. offline, remove_memory() > The node is offlined, since all memory has been removed, so all of > /sys/devices/system/node/nodeX is gone. This is normal. > > 3. add_memory(), online_movable > The node is onlined, so /sys/devices/system/node/nodeX is recreated, > and the memory is added, but just like earlier in this email thread, > the memoryY links are not there. Could you add some printks to see why the sysfs creation failed please? -- Michal Hocko SUSE Labs -- 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>
