[PATCH v6 00/37] Memory allocation profiling

Suren Baghdasaryan
2024-03-21T16:37:11Z

Overview:
Low overhead [1] per-callsite memory allocation profiling. Not just for
debug kernels, overhead low enough to be deployed in production.

Example output:
root@moria-kvm:~# sort -rn /proc/allocinfo
127664128 31168 mm/page_ext.c:270 func:alloc_page_ext
56373248 4737 mm/slub.c:2259 func:alloc_slab_page
14880768 3633 mm/readahead.c:247 func:page_cache_ra_unbounded
14417920 3520 mm/mm_init.c:2530 func:alloc_large_system_hash
13377536 234 block/blk-mq.c:3421 func:blk_mq_alloc_rqs
11718656 2861 mm/filemap.c:1919 func:__filemap_get_folio
9192960 2800 kernel/fork.c:307 func:alloc_thread_stack_node
4206592 4 net/netfilter/nf_conntrack_core.c:2567 func:nf_ct_alloc_hashtable
4136960 1010 drivers/staging/ctagmod/ctagmod.c:20 [ctagmod] func:ctagmod_start
3940352 962 mm/memory.c:4214 func:alloc_anon_folio
2894464 22613 fs/kernfs/dir.c:615 func:__kernfs_new_node
...

Since v5 [2]:
- Added Reviewed-by and Acked-by, per Vlastimil Babka and Miguel Ojeda
- Changed pgalloc_tag_{add|sub} to use number of pages instead of order, per Matthew Wilcox
- Changed pgalloc_tag_sub_bytes to pgalloc_tag_sub_pages and adjusted the usage, per Matthew Wilcox
- Moved static key check before prepare_slab_obj_exts_hook(), per Vlastimil Babka
- Fixed RUST helper, per Miguel Ojeda
- Fixed documentation, per Randy Dunlap
- Rebased over mm-unstable

Usage:
kconfig options:
- CONFIG_MEM_ALLOC_PROFILING
- CONFIG_MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT
- CONFIG_MEM_ALLOC_PROFILING_DEBUG
adds warnings for allocations that weren't accounted because of a
missing annotation

sysctl:
/proc/sys/vm/mem_profiling

Runtime info:
/proc/allocinfo

Notes:

[1]: Overhead
To measure the overhead we are comparing the following configurations:
(1) Baseline with CONFIG_MEMCG_KMEM=n
(2) Disabled by default (CONFIG_MEM_ALLOC_PROFILING=y &&
CONFIG_MEM_ALLOC_PROFILING_BY_DEFAULT=n)
(3) Enabled by default (CONFIG_MEM_ALLOC_PROFILING=y &&
CONFIG_MEM_ALLOC_PROFILING_BY_DEFAULT=y)
(4) Enabled at runtime (CONFIG_MEM_ALLOC_PROFILING=y &&
CONFIG_MEM_ALLOC_PROFILING_BY_DEFAULT=n && /proc/sys/vm/mem_profiling=1)
(5) Baseline with CONFIG_MEMCG_KMEM=y && allocating with __GFP_ACCOUNT
(6) Disabled by default (CONFIG_MEM_ALLOC_PROFILING=y &&
CONFIG_MEM_ALLOC_PROFILING_BY_DEFAULT=n) && CONFIG_MEMCG_KMEM=y
(7) Enabled by default (CONFIG_MEM_ALLOC_PROFILING=y &&
CONFIG_MEM_ALLOC_PROFILING_BY_DEFAULT=y) && CONFIG_MEMCG_KMEM=y

Performance overhead:
To evaluate performance we implemented an in-kernel test executing
multiple get_free_page/free_page and kmalloc/kfree calls with allocation
sizes growing from 8 to 240 bytes with CPU frequency set to max and CPU
affinity set to a specific CPU to minimize the noise. Below are results
from running the test on Ubuntu 22.04.2 LTS with 6.8.0-rc1 kernel on
56 core Intel Xeon:

kmalloc pgalloc
(1 baseline) 6.764s 16.902s
(2 default disabled) 6.793s (+0.43%) 17.007s (+0.62%)
(3 default enabled) 7.197s (+6.40%) 23.666s (+40.02%)
(4 runtime enabled) 7.405s (+9.48%) 23.901s (+41.41%)
(5 memcg) 13.388s (+97.94%) 48.460s (+186.71%)
(6 def disabled+memcg) 13.332s (+97.10%) 48.105s (+184.61%)
(7 def enabled+memcg) 13.446s (+98.78%) 54.963s (+225.18%)

Memory overhead:
Kernel size:

text data bss dec diff
(1) 26515311 18890222 17018880 62424413
(2) 26524728 19423818 16740352 62688898 264485
(3) 26524724 19423818 16740352 62688894 264481
(4) 26524728 19423818 16740352 62688898 264485
(5) 26541782 18964374 16957440 62463596 39183

Memory consumption on a 56 core Intel CPU with 125GB of memory:
Code tags: 192 kB
PageExts: 262144 kB (256MB)
SlabExts: 9876 kB (9.6MB)
PcpuExts: 512 kB (0.5MB)

Total overhead is 0.2% of total memory.

Benchmarks:

Hackbench tests run 100 times:
hackbench -s 512 -l 200 -g 15 -f 25 -P
baseline disabled profiling enabled profiling
avg 0.3543 0.3559 (+0.0016) 0.3566 (+0.0023)
stdev 0.0137 0.0188 0.0077

hackbench -l 10000
baseline disabled profiling enabled profiling
avg 6.4218 6.4306 (+0.0088) 6.5077 (+0.0859)
stdev 0.0933 0.0286 0.0489

stress-ng tests:
stress-ng --class memory --seq 4 -t 60
stress-ng --class cpu --seq 4 -t 60
Results posted at: https://evilpiepirate.org/~kent/memalloc_prof_v4_stress-ng/

[2] https://lore.kernel.org/all/20240306182440.2003814-1-surenb@google.com/

Kent Overstreet (13):
fix missing vmalloc.h includes
asm-generic/io.h: Kill vmalloc.h dependency
mm/slub: Mark slab_free_freelist_hook() __always_inline
scripts/kallysms: Always include __start and __stop symbols
fs: Convert alloc_inode_sb() to a macro
rust: Add a rust helper for krealloc()
mempool: Hook up to memory allocation profiling
mm: percpu: Introduce pcpuobj_ext
mm: percpu: Add codetag reference into pcpuobj_ext
mm: vmalloc: Enable memory allocation profiling
rhashtable: Plumb through alloc tag
MAINTAINERS: Add entries for code tagging and memory allocation
profiling
memprofiling: Documentation

Suren Baghdasaryan (24):
mm: introduce slabobj_ext to support slab object extensions
mm: introduce __GFP_NO_OBJ_EXT flag to selectively prevent slabobj_ext
creation
mm/slab: introduce SLAB_NO_OBJ_EXT to avoid obj_ext creation
slab: objext: introduce objext_flags as extension to
page_memcg_data_flags
lib: code tagging framework
lib: code tagging module support
lib: prevent module unloading if memory is not freed
lib: add allocation tagging support for memory allocation profiling
lib: introduce support for page allocation tagging
lib: introduce early boot parameter to avoid page_ext memory overhead
mm: percpu: increase PERCPU_MODULE_RESERVE to accommodate allocation
tags
change alloc_pages name in dma_map_ops to avoid name conflicts
mm: enable page allocation tagging
mm: create new codetag references during page splitting
mm: fix non-compound multi-order memory accounting in __free_pages
mm/page_ext: enable early_page_ext when
CONFIG_MEM_ALLOC_PROFILING_DEBUG=y
lib: add codetag reference into slabobj_ext
mm/slab: add allocation accounting into slab allocation and free paths
mm/slab: enable slab allocation tagging for kmalloc and friends
mm: percpu: enable per-cpu allocation tagging
lib: add memory allocations report in show_mem()
codetag: debug: skip objext checking when it's for objext itself
codetag: debug: mark codetags for reserved pages as empty
codetag: debug: introduce OBJEXTS_ALLOC_FAIL to mark failed slab_ext
allocations

Documentation/admin-guide/sysctl/vm.rst | 16 +
Documentation/filesystems/proc.rst | 29 ++
Documentation/mm/allocation-profiling.rst | 100 ++++++
Documentation/mm/index.rst | 1 +
MAINTAINERS | 17 +
arch/alpha/kernel/pci_iommu.c | 2 +-
arch/alpha/lib/checksum.c | 1 +
arch/alpha/lib/fpreg.c | 1 +
arch/alpha/lib/memcpy.c | 1 +
arch/arm/kernel/irq.c | 1 +
arch/arm/kernel/traps.c | 1 +
arch/arm64/kernel/efi.c | 1 +
arch/loongarch/include/asm/kfence.h | 1 +
arch/mips/jazz/jazzdma.c | 2 +-
arch/powerpc/kernel/dma-iommu.c | 2 +-
arch/powerpc/kernel/iommu.c | 1 +
arch/powerpc/mm/mem.c | 1 +
arch/powerpc/platforms/ps3/system-bus.c | 4 +-
arch/powerpc/platforms/pseries/vio.c | 2 +-
arch/riscv/kernel/elf_kexec.c | 1 +
arch/riscv/kernel/probes/kprobes.c | 1 +
arch/s390/kernel/cert_store.c | 1 +
arch/s390/kernel/ipl.c | 1 +
arch/x86/include/asm/io.h | 1 +
arch/x86/kernel/amd_gart_64.c | 2 +-
arch/x86/kernel/cpu/sgx/main.c | 1 +
arch/x86/kernel/irq_64.c | 1 +
arch/x86/mm/fault.c | 1 +
drivers/accel/ivpu/ivpu_mmu_context.c | 1 +
drivers/gpu/drm/gma500/mmu.c | 1 +
drivers/gpu/drm/i915/gem/i915_gem_pages.c | 1 +
.../gpu/drm/i915/gem/selftests/mock_dmabuf.c | 1 +
drivers/gpu/drm/i915/gt/shmem_utils.c | 1 +
drivers/gpu/drm/i915/gvt/firmware.c | 1 +
drivers/gpu/drm/i915/gvt/gtt.c | 1 +
drivers/gpu/drm/i915/gvt/handlers.c | 1 +
drivers/gpu/drm/i915/gvt/mmio.c | 1 +
drivers/gpu/drm/i915/gvt/vgpu.c | 1 +
drivers/gpu/drm/i915/intel_gvt.c | 1 +
drivers/gpu/drm/imagination/pvr_vm_mips.c | 1 +
drivers/gpu/drm/mediatek/mtk_drm_gem.c | 1 +
drivers/gpu/drm/omapdrm/omap_gem.c | 1 +
drivers/gpu/drm/v3d/v3d_bo.c | 1 +
drivers/gpu/drm/vmwgfx/vmwgfx_binding.c | 1 +
drivers/gpu/drm/vmwgfx/vmwgfx_cmd.c | 1 +
drivers/gpu/drm/vmwgfx/vmwgfx_devcaps.c | 1 +
drivers/gpu/drm/vmwgfx/vmwgfx_drv.c | 1 +
drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c | 1 +
drivers/gpu/drm/vmwgfx/vmwgfx_ioctl.c | 1 +
drivers/gpu/drm/xen/xen_drm_front_gem.c | 1 +
drivers/hwtracing/coresight/coresight-trbe.c | 1 +
drivers/iommu/dma-iommu.c | 2 +-
.../marvell/octeon_ep/octep_pfvf_mbox.c | 1 +
.../marvell/octeon_ep_vf/octep_vf_mbox.c | 1 +
.../net/ethernet/microsoft/mana/hw_channel.c | 1 +
drivers/parisc/ccio-dma.c | 2 +-
drivers/parisc/sba_iommu.c | 2 +-
drivers/platform/x86/uv_sysfs.c | 1 +
drivers/scsi/mpi3mr/mpi3mr_transport.c | 2 +
drivers/staging/media/atomisp/pci/hmm/hmm.c | 2 +-
drivers/vfio/pci/pds/dirty.c | 1 +
drivers/virt/acrn/mm.c | 1 +
drivers/virtio/virtio_mem.c | 1 +
drivers/xen/grant-dma-ops.c | 2 +-
drivers/xen/swiotlb-xen.c | 2 +-
include/asm-generic/codetag.lds.h | 14 +
include/asm-generic/io.h | 1 -
include/asm-generic/vmlinux.lds.h | 3 +
include/linux/alloc_tag.h | 205 +++++++++++
include/linux/codetag.h | 81 +++++
include/linux/dma-map-ops.h | 2 +-
include/linux/fortify-string.h | 5 +-
include/linux/fs.h | 6 +-
include/linux/gfp.h | 126 ++++---
include/linux/gfp_types.h | 11 +
include/linux/memcontrol.h | 56 ++-
include/linux/mempool.h | 73 ++--
include/linux/mm.h | 9 +
include/linux/mm_types.h | 4 +-
include/linux/page_ext.h | 1 -
include/linux/pagemap.h | 9 +-
include/linux/pds/pds_common.h | 2 +
include/linux/percpu.h | 27 +-
include/linux/pgalloc_tag.h | 134 +++++++
include/linux/rhashtable-types.h | 11 +-
include/linux/sched.h | 24 ++
include/linux/slab.h | 179 +++++-----
include/linux/string.h | 4 +-
include/linux/vmalloc.h | 60 +++-
include/rdma/rdmavt_qp.h | 1 +
init/Kconfig | 4 +
kernel/dma/mapping.c | 4 +-
kernel/kallsyms_selftest.c | 2 +-
kernel/module/main.c | 29 +-
lib/Kconfig.debug | 31 ++
lib/Makefile | 3 +
lib/alloc_tag.c | 243 +++++++++++++
lib/codetag.c | 283 +++++++++++++++
lib/rhashtable.c | 28 +-
mm/compaction.c | 7 +-
mm/debug_vm_pgtable.c | 1 +
mm/filemap.c | 6 +-
mm/huge_memory.c | 2 +
mm/kfence/core.c | 14 +-
mm/kfence/kfence.h | 4 +-
mm/memcontrol.c | 56 +--
mm/mempolicy.c | 52 +--
mm/mempool.c | 36 +-
mm/mm_init.c | 13 +-
mm/nommu.c | 64 ++--
mm/page_alloc.c | 71 ++--
mm/page_ext.c | 13 +
mm/page_owner.c | 2 +-
mm/percpu-internal.h | 26 +-
mm/percpu.c | 120 +++----
mm/show_mem.c | 26 ++
mm/slab.h | 51 ++-
mm/slab_common.c | 6 +-
mm/slub.c | 327 +++++++++++++++---
mm/util.c | 44 +--
mm/vmalloc.c | 88 ++---
rust/helpers.c | 8 +
scripts/kallsyms.c | 13 +
scripts/module.lds.S | 7 +
sound/pci/hda/cs35l41_hda.c | 1 +
125 files changed, 2319 insertions(+), 652 deletions(-)
create mode 100644 Documentation/mm/allocation-profiling.rst
create mode 100644 include/asm-generic/codetag.lds.h
create mode 100644 include/linux/alloc_tag.h
create mode 100644 include/linux/codetag.h
create mode 100644 include/linux/pgalloc_tag.h
create mode 100644 lib/alloc_tag.c
create mode 100644 lib/codetag.c

base-commit: a824831a082f1d8f9b51a4c0598e633d38555fcf
--
2.44.0.291.gc1ea87d7ee-goog