This series fixes the access of uninitialized memmaps when shrinking
zones/nodes and when removing memory. Also, it contains all fixes for
crashes that can be triggered when removing certain namespace using
memunmap_pages() - ZONE_DEVICE, reported by Aneesh.
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).
We continue shrinking !ZONE_DEVICE zones, however, 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. I didn't test the ZONE_DEVICE part.
v4 -> v6:
- "mm/memunmap: Don't access uninitialized memmap in memunmap_pages()"
-- Minimize code changes, rephrase subject and description
- "mm/memory_hotplug: Don't access uninitialized memmaps in shrink_zone_span()"
-- Add ifdef to make it compile without ZONE_DEVICE
v4 -> v5:
- "mm/memory_hotplug: Don't access uninitialized memmaps in shrink_zone_span()"
-- Add more details why ZONE_DEVICE is special
- Include two patches from Aneesh
-- "mm/memunmap: Use the correct start and end pfn when removing pages
from zone"
-- "mm/memmap_init: Update variable name in memmap_init_zone"
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.ku...@linux.ibm.com>
Cc: Andrew Morton <a...@linux-foundation.org>
Cc: Dan Williams <dan.j.willi...@intel.com>
Cc: Michal Hocko <mho...@suse.com>
Aneesh Kumar K.V (2):
mm/memunmap: Don't access uninitialized memmap in memunmap_pages()
mm/memmap_init: Update variable name in memmap_init_zone
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 | 186 ++++++++++++---------------------
mm/memremap.c | 13 ++-
mm/page_alloc.c | 8 +-
11 files changed, 90 insertions(+), 151 deletions(-)
--
2.21.0
