[v4,0/4] KVM: mm: count KVM mmu usage in memory stats

Message

Yosry Ahmed April 29, 2022, 8:11 p.m. UTC

We keep track of several kernel memory stats (total kernel memory, page
tables, stack, vmalloc, etc) on multiple levels (global, per-node,
per-memcg, etc). These stats give insights to users to how much memory
is used by the kernel and for what purposes.

Currently, memory used by kvm mmu is not accounted in any of those
kernel memory stats. This patch series accounts the memory pages
used by KVM for page tables in those stats in a new
NR_SECONDARY_PAGETABLE stat.

---

Changes in V4:
- Changed accounting hooks in arm64 to only account s2 page tables and
  refactored them to a much cleaner form, based on recommendations from
  Oliver Upton and Marc Zyngier.
- Dropped patches for mips and riscv. I am not interested in those archs
  anyway and don't have the resources to test them. I posted them for
  completeness but it doesn't seem like anyone was interested.

Changes in V3:
- Added NR_SECONDARY_PAGETABLE instead of piggybacking on NR_PAGETABLE
  stats.

Changes in V2:
- Added accounting stats for other archs than x86.
- Changed locations in the code where x86 KVM page table stats were
  accounted based on suggestions from Sean Christopherson.

---

Yosry Ahmed (4):
  mm: add NR_SECONDARY_PAGETABLE to count secondary page table uses.
  KVM: mmu: add a helper to account memory used by KVM mmu.
  KVM: x86/mmu: count KVM mmu usage in secondary pagetable stats.
  KVM: arm64/mmu: count KVM s2 mmu usage in secondary pagetable stats

 Documentation/admin-guide/cgroup-v2.rst |  5 ++++
 Documentation/filesystems/proc.rst      |  4 +++
 arch/arm64/kvm/mmu.c                    | 35 ++++++++++++++++++++++---
 arch/x86/kvm/mmu/mmu.c                  | 16 +++++++++--
 arch/x86/kvm/mmu/tdp_mmu.c              | 16 +++++++++--
 drivers/base/node.c                     |  2 ++
 fs/proc/meminfo.c                       |  2 ++
 include/linux/kvm_host.h                |  9 +++++++
 include/linux/mmzone.h                  |  1 +
 mm/memcontrol.c                         |  1 +
 mm/page_alloc.c                         |  6 ++++-
 mm/vmstat.c                             |  1 +
 12 files changed, 89 insertions(+), 9 deletions(-)