On 30.08.19 11:14, David Hildenbrand wrote: > This series fixes the access of uninitialized memmaps when shrinking > zones/nodes and when removing memory. > > We stop trying to shrink ZONE_DEVICE, as it's buggy, fixing it would be > more involved (we don't have SECTION_IS_ONLINE as an indicator), and > shrinking is only of limited use (set_zone_contiguous() cannot detect > the ZONE_DEVICE as contiguous). As far as I can tell, this should be fine > for ZONE_DEVICE. > > We continue shrinking zones, but I reduced the amount of code to a > minimum. Shrinking is especially necessary to keep zone->contiguous set > where possible, especially on memory unplug of DIMMs at zone boundaries. > > -------------------------------------------------------------------------- > > Zones are now properly shrunk when offlining memory blocks or when > onlining failed. This allows to properly shrink zones on memory unplug > even if the separate memory blocks of a DIMM were onlined to different > zones or re-onlined to a different zone after offlining. > > Example: > > :/# cat /proc/zoneinfo > Node 1, zone Movable > spanned 0 > present 0 > managed 0 > :/# echo "online_movable" > /sys/devices/system/memory/memory41/state > :/# echo "online_movable" > /sys/devices/system/memory/memory43/state > :/# cat /proc/zoneinfo > Node 1, zone Movable > spanned 98304 > present 65536 > managed 65536 > :/# echo 0 > /sys/devices/system/memory/memory43/online > :/# cat /proc/zoneinfo > Node 1, zone Movable > spanned 32768 > present 32768 > managed 32768 > :/# echo 0 > /sys/devices/system/memory/memory41/online > :/# cat /proc/zoneinfo > Node 1, zone Movable > spanned 0 > present 0 > managed 0 > > -------------------------------------------------------------------------- > > I tested this with DIMMs on x86, but didn't test the ZONE_DEVICE part yet. > > > v3 -> v4: > - Drop "mm/memremap: Get rid of memmap_init_zone_device()" > -- As Alexander noticed, it was messy either way :) > - Drop "mm/memory_hotplug: Exit early in __remove_pages() on BUGs" > - Drop "mm: Exit early in set_zone_contiguous() if already contiguous" > - Drop "mm/memory_hotplug: Optimize zone shrinking code when checking for > holes" > - Merged "mm/memory_hotplug: Remove pages from a zone before removing > memory" and "mm/memory_hotplug: Remove zone parameter from > __remove_pages()" into "mm/memory_hotplug: Shrink zones when offlining > memory" > - Added "mm/memory_hotplug: Poison memmap in remove_pfn_range_from_zone()" > - Stop shrinking ZONE_DEVICE > - Reshuffle patches, moving all fixes to the front. Add Fixes: tags. > - Change subject/description of various patches > - Minor changes (too many to mention) > > > Cc: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxx> > Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> > Cc: Dan Williams <dan.j.williams@xxxxxxxxx> > Cc: Michal Hocko <mhocko@xxxxxxxx> > > > David Hildenbrand (8): > mm/memory_hotplug: Don't access uninitialized memmaps in > shrink_pgdat_span() > mm/memory_hotplug: Don't access uninitialized memmaps in > shrink_zone_span() > mm/memory_hotplug: Shrink zones when offlining memory > mm/memory_hotplug: Poison memmap in remove_pfn_range_from_zone() > mm/memory_hotplug: We always have a zone in > find_(smallest|biggest)_section_pfn > mm/memory_hotplug: Don't check for "all holes" in shrink_zone_span() > mm/memory_hotplug: Drop local variables in shrink_zone_span() > mm/memory_hotplug: Cleanup __remove_pages() > > arch/arm64/mm/mmu.c | 4 +- > arch/ia64/mm/init.c | 4 +- > arch/powerpc/mm/mem.c | 3 +- > arch/s390/mm/init.c | 4 +- > arch/sh/mm/init.c | 4 +- > arch/x86/mm/init_32.c | 4 +- > arch/x86/mm/init_64.c | 4 +- > include/linux/memory_hotplug.h | 7 +- > mm/memory_hotplug.c | 184 +++++++++++---------------------- > mm/memremap.c | 10 +- > 10 files changed, 80 insertions(+), 148 deletions(-) > @Andrew, if there are no further comments, can we give this some testing? -- Thanks, David / dhildenb
