[PATCH v4 00/36] Memory allocation profiling

Suren Baghdasaryan
2024-02-21T19:41:00Z

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 v3:
- Dropped patch changing string_get_size() [2] as not needed
- Dropped patch modifying xfs allocators [3] as non needed,
per Dave Chinner
- Added Reviewed-by, per Kees Cook
- Moved prepare_slab_obj_exts_hook() and alloc_slab_obj_exts() where they
are used, per Vlastimil Babka
- Fixed SLAB_NO_OBJ_EXT definition to use unused bit, per Vlastimil Babka
- Refactored patch [4] into other patches, per Vlastimil Babka
- Replaced snprintf() with seq_buf_printf(), per Kees Cook
- Changed output to report bytes, per Andrew Morton and Pasha Tatashin
- Changed output to report [module] only for loadable modules,
per Vlastimil Babka
- Moved mem_alloc_profiling_enabled() check earlier, per Vlastimil Babka
- Changed the code to handle page splitting to be more understandable,
per Vlastimil Babka
- Moved alloc_tagging_slab_free_hook(), mark_objexts_empty(),
mark_failed_objexts_alloc() and handle_failed_objexts_alloc(),
per Vlastimil Babka
- Fixed loss of __alloc_size(1, 2) in kvmalloc functions,
per Vlastimil Babka
- Refactored the code in show_mem() to avoid memory allocations,
per Michal Hocko
- Changed to trylock in show_mem() to avoid blocking in atomic context,
per Tetsuo Handa
- Added mm mailing list into MAINTAINERS, per Kees Cook
- Added base commit SHA, per Andy Shevchenko
- Added a patch with documentation, per Jani Nikula
- Fixed 0day bugs
- Added benchmark results [5], per Steven Rostedt
- Rebased over Linux 6.8-rc5

Items not yet addressed:
- An early_boot option to prevent pageext overhead. We are looking into
ways for using the same sysctr instead of adding additional early boot
parameter.

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.

[2] https://lore.kernel.org/all/20240212213922.783301-2-surenb@google.com/
[3] https://lore.kernel.org/all/20240212213922.783301-26-surenb@google.com/
[4] https://lore.kernel.org/all/20240212213922.783301-9-surenb@google.com/
[5] 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/

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 (23):
mm: enumerate all gfp flags
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
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/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 | 86 ++++++
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 +
.../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 | 195 ++++++++++++
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 | 101 +++++--
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 | 110 +++++++
include/linux/rhashtable-types.h | 11 +-
include/linux/sched.h | 24 ++
include/linux/slab.h | 175 +++++------
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 | 25 +-
lib/Kconfig.debug | 31 ++
lib/Makefile | 3 +
lib/alloc_tag.c | 204 +++++++++++++
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 | 66 ++--
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 | 126 ++++++--
mm/slab_common.c | 6 +-
mm/slub.c | 244 +++++++++++----
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 +
123 files changed, 2269 insertions(+), 682 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: 39133352cbed6626956d38ed72012f49b0421e7b
--
2.44.0.rc0.258.g7320e95886-goog