[PATCH v5 0/4] mm: convert totalram_pages, totalhigh_pages and managed pages to atomic

From: Arun KS
Date: Tue Nov 13 2018 - 01:33:52 EST


This series convert totalram_pages, totalhigh_pages and
zone->managed_pages to atomic variables.

The patch was comiple tested on x86(x86_64_defconfig & i386_defconfig)
on 4.20-rc2. And memory hotplug tested on arm64, but on an older version
of kernel.

totalram_pages, zone->managed_pages and totalhigh_pages updates
are protected by managed_page_count_lock, but readers never care
about it. Convert these variables to atomic to avoid readers
potentially seeing a store tear.

Main motivation was that managed_page_count_lock handling was
complicating things. It was discussed in length here,
https://lore.kernel.org/patchwork/patch/995739/#1181785
It seemes better to remove the lock and convert variables
to atomic. With the change, preventing poteintial store-to-read
tearing comes as a bonus.

Changes in v5:
- totalram_pgs renamed to nr_pages.
https://lore.kernel.org/patchwork/patch/1011293/#1194248

Changes in v4:
- Fixed kbuild test robot error.
- Modified changelog.
- Rebased to 4.20.-rc2

Changes in v3:
- Fixed kbuild test robot errors.
- Modified changelogs to be more clear.
- EXPORT_SYMBOL for _totalram_pages and _totalhigh_pages.

Arun KS (4):
mm: reference totalram_pages and managed_pages once per function
mm: convert zone->managed_pages to atomic variable
mm: convert totalram_pages and totalhigh_pages variables to atomic
mm: Remove managed_page_count spinlock

arch/csky/mm/init.c | 4 +-
arch/powerpc/platforms/pseries/cmm.c | 10 ++--
arch/s390/mm/init.c | 2 +-
arch/um/kernel/mem.c | 4 +-
arch/x86/kernel/cpu/microcode/core.c | 5 +-
drivers/char/agp/backend.c | 4 +-
drivers/gpu/drm/amd/amdkfd/kfd_crat.c | 2 +-
drivers/gpu/drm/i915/i915_gem.c | 2 +-
drivers/gpu/drm/i915/selftests/i915_gem_gtt.c | 4 +-
drivers/hv/hv_balloon.c | 19 +++----
drivers/md/dm-bufio.c | 2 +-
drivers/md/dm-crypt.c | 2 +-
drivers/md/dm-integrity.c | 2 +-
drivers/md/dm-stats.c | 2 +-
drivers/media/platform/mtk-vpu/mtk_vpu.c | 2 +-
drivers/misc/vmw_balloon.c | 2 +-
drivers/parisc/ccio-dma.c | 4 +-
drivers/parisc/sba_iommu.c | 4 +-
drivers/staging/android/ion/ion_system_heap.c | 2 +-
drivers/xen/xen-selfballoon.c | 6 +--
fs/ceph/super.h | 2 +-
fs/file_table.c | 7 +--
fs/fuse/inode.c | 2 +-
fs/nfs/write.c | 2 +-
fs/nfsd/nfscache.c | 2 +-
fs/ntfs/malloc.h | 2 +-
fs/proc/base.c | 2 +-
include/linux/highmem.h | 28 ++++++++++-
include/linux/mm.h | 27 +++++++++-
include/linux/mmzone.h | 15 +++---
include/linux/swap.h | 1 -
kernel/fork.c | 5 +-
kernel/kexec_core.c | 5 +-
kernel/power/snapshot.c | 2 +-
lib/show_mem.c | 2 +-
mm/highmem.c | 5 +-
mm/huge_memory.c | 2 +-
mm/kasan/quarantine.c | 2 +-
mm/memblock.c | 6 +--
mm/mm_init.c | 2 +-
mm/oom_kill.c | 2 +-
mm/page_alloc.c | 72 +++++++++++++--------------
mm/shmem.c | 7 +--
mm/slab.c | 2 +-
mm/swap.c | 2 +-
mm/util.c | 2 +-
mm/vmalloc.c | 4 +-
mm/vmstat.c | 4 +-
mm/workingset.c | 2 +-
mm/zswap.c | 4 +-
net/dccp/proto.c | 7 +--
net/decnet/dn_route.c | 2 +-
net/ipv4/tcp_metrics.c | 2 +-
net/netfilter/nf_conntrack_core.c | 7 +--
net/netfilter/xt_hashlimit.c | 5 +-
net/sctp/protocol.c | 7 +--
security/integrity/ima/ima_kexec.c | 2 +-
57 files changed, 196 insertions(+), 142 deletions(-)

--
1.9.1