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linux/mm
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Marco Elver 105b50d9bb kfence: limit currently covered allocations when pool nearly full 
[ Upstream commit 08f6b10630 ]

One of KFENCE's main design principles is that with increasing uptime,
allocation coverage increases sufficiently to detect previously
undetected bugs.

We have observed that frequent long-lived allocations of the same source
(e.g.  pagecache) tend to permanently fill up the KFENCE pool with
increasing system uptime, thus breaking the above requirement.  The
workaround thus far had been increasing the sample interval and/or
increasing the KFENCE pool size, but is no reliable solution.

To ensure diverse coverage of allocations, limit currently covered
allocations of the same source once pool utilization reaches 75%
(configurable via `kfence.skip_covered_thresh`) or above.  The effect is
retaining reasonable allocation coverage when the pool is close to full.

A side-effect is that this also limits frequent long-lived allocations
of the same source filling up the pool permanently.

Uniqueness of an allocation for coverage purposes is based on its
(partial) allocation stack trace (the source).  A Counting Bloom filter
is used to check if an allocation is covered; if the allocation is
currently covered, the allocation is skipped by KFENCE.

Testing was done using:

	(a) a synthetic workload that performs frequent long-lived
	    allocations (default config values; sample_interval=1;
	    num_objects=63), and

	(b) normal desktop workloads on an otherwise idle machine where
	    the problem was first reported after a few days of uptime
	    (default config values).

In both test cases the sampled allocation rate no longer drops to zero
at any point.  In the case of (b) we observe (after 2 days uptime) 15%
unique allocations in the pool, 77% pool utilization, with 20% "skipped
allocations (covered)".

[elver@google.com: simplify and just use hash_32(), use more random stack_hash_seed]
  Link: https://lkml.kernel.org/r/YU3MRGaCaJiYht5g@elver.google.com
[elver@google.com: fix 32 bit]

Link: https://lkml.kernel.org/r/20210923104803.2620285-4-elver@google.com
Signed-off-by: Marco Elver <elver@google.com>
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
Acked-by: Alexander Potapenko <glider@google.com>
Cc: Aleksandr Nogikh <nogikh@google.com>
Cc: Jann Horn <jannh@google.com>
Cc: Taras Madan <tarasmadan@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2022-04-13 20:59:00 +02:00
..
damon mm/damon/dbgfs: fix 'struct pid' leaks in 'dbgfs_target_ids_write()' 2022-01-05 12:42:39 +01:00
kasan kasan: fix quarantine conflicting with init_on_free 2022-03-08 19:12:38 +01:00
kfence kfence: limit currently covered allocations when pool nearly full 2022-04-13 20:59:00 +02:00
backing-dev.c mm: bdi: initialize bdi_min_ratio when bdi is unregistered 2021-12-14 10:57:11 +01:00
balloon_compaction.c mm: fix typos in comments 2021-05-07 00:26:35 -07:00
bootmem_info.c mm/bootmem_info.c: mark __init on register_page_bootmem_info_section 2021-09-03 09:58:14 -07:00
cleancache.c
cma_debug.c mm/cma: change cma mutex to irq safe spinlock 2021-05-05 11:27:21 -07:00
cma_sysfs.c mm: cma: support sysfs 2021-05-05 11:27:24 -07:00
cma.c mm: use proper type for cma_[alloc|release] 2021-05-05 11:27:24 -07:00
cma.h mm: cma: support sysfs 2021-05-05 11:27:24 -07:00
compaction.c Merge branch 'akpm' (patches from Andrew) 2021-09-08 12:55:35 -07:00
debug_page_ref.c
debug_vm_pgtable.c mm/debug_vm_pgtable: remove pte entry from the page table 2022-02-08 18:34:05 +01:00
debug.c mm/debug: sync up latest migrate_reason to migrate_reason_names 2021-09-24 16:13:35 -07:00
dmapool.c mm/dmapool: use DEVICE_ATTR_RO macro 2021-06-29 10:53:52 -07:00
early_ioremap.c mm/early_ioremap.c: remove redundant early_ioremap_shutdown() 2021-09-08 11:50:24 -07:00
fadvise.c
failslab.c
filemap.c mm/filemap: Fix handling of THPs in generic_file_buffered_read() 2022-03-02 11:47:47 +01:00
frontswap.c mm/mempool: minor coding style tweaks 2021-05-05 11:27:27 -07:00
gup_test.c selftests/vm: gup_test: test faulting in kernel, and verify pinnable pages 2021-05-05 11:27:26 -07:00
gup_test.h selftests/vm: gup_test: fix test flag 2021-05-05 11:27:26 -07:00
gup.c Revert "mm/gup: small refactoring: simplify try_grab_page()" 2022-02-05 12:38:57 +01:00
highmem.c kmap_local: don't assume kmap PTEs are linear arrays in memory 2021-11-25 09:48:43 +01:00
hmm.c mm/hmm.c: allow VM_MIXEDMAP to work with hmm_range_fault 2022-01-27 11:05:43 +01:00
huge_memory.c mm: filemap: check if THP has hwpoisoned subpage for PMD page fault 2021-10-28 17:18:55 -07:00
hugetlb_cgroup.c hugetlb: make free_huge_page irq safe 2021-05-05 11:27:22 -07:00
hugetlb_vmemmap.c mm: hugetlb: introduce CONFIG_HUGETLB_PAGE_FREE_VMEMMAP_DEFAULT_ON 2021-06-30 20:47:26 -07:00
hugetlb_vmemmap.h mm: hugetlb: introduce nr_free_vmemmap_pages in the struct hstate 2021-06-30 20:47:25 -07:00
hugetlb.c hugetlbfs: flush TLBs correctly after huge_pmd_unshare 2021-11-25 09:49:07 +01:00
hwpoison-inject.c mm: hwpoison: don't drop slab caches for offlining non-LRU page 2021-09-03 09:58:15 -07:00
init-mm.c mm: add setup_initial_init_mm() helper 2021-07-08 11:48:21 -07:00
internal.h mm/numa: automatically generate node migration order 2021-09-03 09:58:16 -07:00
interval_tree.c mm/interval_tree: add comments to improve code readability 2021-04-30 11:20:38 -07:00
io-mapping.c mm: add a io_mapping_map_user helper 2021-04-30 11:20:39 -07:00
ioremap.c mm: move ioremap_page_range to vmalloc.c 2021-09-08 11:50:24 -07:00
Kconfig kmap_local: don't assume kmap PTEs are linear arrays in memory 2021-11-25 09:48:43 +01:00
Kconfig.debug
khugepaged.c mm: khugepaged: skip huge page collapse for special files 2021-10-28 17:18:55 -07:00
kmemleak.c mm/kmemleak: reset tag when compare object pointer 2022-04-08 14:22:56 +02:00
ksm.c mm/ksm: remove old GCC 4.9+ check 2021-09-13 10:18:28 -07:00
list_lru.c mm: vmscan: consolidate shrinker_maps handling code 2021-05-05 11:27:23 -07:00
maccess.c ARM: 9115/1: mm/maccess: fix unaligned copy_{from,to}_kernel_nofault 2021-08-20 11:39:25 +01:00
madvise.c Revert "mm: madvise: skip unmapped vma holes passed to process_madvise" 2022-04-08 14:22:56 +02:00
Makefile mm: introduce Data Access MONitor (DAMON) 2021-09-08 11:50:24 -07:00
mapping_dirty_helpers.c mm/mapping_dirty_helpers: remove double Note in kerneldoc 2021-07-01 11:06:02 -07:00
memblock.c memblock: use kfree() to release kmalloced memblock regions 2022-03-02 11:48:10 +01:00
memcontrol.c mm/memcontrol: return 1 from cgroup.memory __setup() handler 2022-04-08 14:24:13 +02:00
memfd.c memfd: fix F_SEAL_WRITE after shmem huge page allocated 2022-03-08 19:12:48 +01:00
memory_hotplug.c Merge branch 'akpm' (patches from Andrew) 2021-09-08 12:55:35 -07:00
memory-failure.c mm/hwpoison: clear MF_COUNT_INCREASED before retrying get_any_page() 2021-12-29 12:28:58 +01:00
memory.c mm,hwpoison: unmap poisoned page before invalidation 2022-04-08 14:22:56 +02:00
mempolicy.c mempolicy: mbind_range() set_policy() after vma_merge() 2022-04-08 14:22:54 +02:00
mempool.c kasan: use separate (un)poison implementation for integrated init 2021-06-04 19:32:21 +01:00
memremap.c mm/memory_hotplug: remove nid parameter from arch_remove_memory() 2021-09-08 11:50:23 -07:00
memtest.c
migrate.c mm/migrate: fix CPUHP state to update node demotion order 2021-10-18 20:22:03 -10:00
mincore.c
mlock.c mm/mlock: fix two bugs in user_shm_lock() 2022-04-08 14:22:52 +02:00
mm_init.c include/linux/page-flags-layout.h: cleanups 2021-04-30 11:20:42 -07:00
mmap_lock.c mm: mmap_lock: fix disabling preemption directly 2021-07-23 17:43:28 -07:00
mmap.c mm/mmap: return 1 from stack_guard_gap __setup() handler 2022-04-08 14:24:13 +02:00
mmu_gather.c mm: eliminate "expecting prototype" kernel-doc warnings 2021-04-16 16:10:36 -07:00
mmu_notifier.c mm/mmu_notifiers: ensure range_end() is paired with range_start() 2021-03-25 09:22:55 -07:00
mmzone.c
mprotect.c mm: don't try to NUMA-migrate COW pages that have other uses 2022-02-23 12:03:03 +01:00
mremap.c mm/mremap: fix memory account on do_munmap() failure 2021-09-03 09:58:14 -07:00
msync.c mm/msync: exit early when the flags is an MS_ASYNC and start < vm_start 2021-04-30 11:20:37 -07:00
nommu.c Merge tag 'denywrite-for-5.15' of git://github.com/davidhildenbrand/linux 2021-09-04 11:35:47 -07:00
oom_kill.c mm, oom: do not trigger out_of_memory from the #PF 2021-11-18 19:17:16 +01:00
page_alloc.c mm/pages_alloc.c: don't create ZONE_MOVABLE beyond the end of a node 2022-04-08 14:22:54 +02:00
page_counter.c mm: page_counter: mitigate consequences of a page_counter underflow 2021-04-30 11:20:38 -07:00
page_ext.c mm/migrate: add CPU hotplug to demotion #ifdef 2021-10-18 20:22:02 -10:00
page_idle.c mm/idle_page_tracking: make PG_idle reusable 2021-09-08 11:50:24 -07:00
page_io.c swap: fix swapfile read/write offset 2021-03-02 17:25:46 -07:00
page_isolation.c Merge branch 'akpm' (patches from Andrew) 2021-09-08 12:55:35 -07:00
page_owner.c mm: remove pfn_valid_within() and CONFIG_HOLES_IN_ZONE 2021-09-08 11:50:22 -07:00
page_poison.c mm: page_poison: print page info when corruption is caught 2021-04-30 11:20:36 -07:00
page_reporting.c mm/page_reporting: allow driver to specify reporting order 2021-06-29 10:53:47 -07:00
page_reporting.h mm/page_reporting: export reporting order as module parameter 2021-06-29 10:53:47 -07:00
page_vma_mapped.c mm: device exclusive memory access 2021-07-01 11:06:03 -07:00
page-writeback.c Merge branch 'akpm' (patches from Andrew) 2021-09-03 10:08:28 -07:00
pagewalk.c mm: pagewalk: fix walk for hugepage tables 2021-06-29 10:53:49 -07:00
percpu-internal.h Merge branch 'for-5.14' of git://git.kernel.org/pub/scm/linux/kernel/git/dennis/percpu 2021-07-01 17:17:24 -07:00
percpu-km.c percpu: flush tlb in pcpu_reclaim_populated() 2021-07-04 18:30:17 +00:00
percpu-stats.c percpu: rework memcg accounting 2021-06-05 20:43:15 +00:00
percpu-vm.c percpu: flush tlb in pcpu_reclaim_populated() 2021-07-04 18:30:17 +00:00
percpu.c Merge branch 'akpm' (patches from Andrew) 2021-09-08 12:55:35 -07:00
pgalloc-track.h mm: fix typos in comments 2021-05-07 00:26:35 -07:00
pgtable-generic.c mm/thp: fix __split_huge_pmd_locked() on shmem migration entry 2021-06-16 09:24:42 -07:00
process_vm_access.c mm/process_vm_access.c: remove duplicate include 2021-05-05 11:27:27 -07:00
ptdump.c mm: ptdump: fix build failure 2021-04-16 16:10:37 -07:00
readahead.c mm: Protect operations adding pages to page cache with invalidate_lock 2021-07-13 13:14:27 +02:00
rmap.c Merge branch 'akpm' (patches from Andrew) 2021-09-08 12:55:35 -07:00
rodata_test.c
secretmem.c mm/secretmem: avoid letting secretmem_users drop to zero 2021-10-28 17:18:55 -07:00
shmem.c shmem: fix a race between shmem_unused_huge_shrink and shmem_evict_inode 2022-01-27 11:03:01 +01:00
shuffle.c mm: eliminate "expecting prototype" kernel-doc warnings 2021-04-16 16:10:36 -07:00
shuffle.h mm/shuffle: fix section mismatch warning 2021-05-22 15:09:07 -10:00
slab_common.c mm: slub: move flush_cpu_slab() invocations __free_slab() invocations out of IRQ context 2021-09-04 01:12:23 +02:00
slab.c mm: kfence: fix missing objcg housekeeping for SLAB 2022-04-08 14:22:46 +02:00
slab.h mm: kmemleak: slob: respect SLAB_NOLEAKTRACE flag 2021-11-25 09:48:42 +01:00
slob.c mm: Don't build mm_dump_obj() on CONFIG_PRINTK=n kernels 2021-03-08 14:18:46 -08:00
slub.c mm/slub: fix endianness bug for alloc/free_traces attributes 2021-12-14 10:57:11 +01:00
sparse-vmemmap.c mm: sparsemem: split the huge PMD mapping of vmemmap pages 2021-06-30 20:47:26 -07:00
sparse.c mm: introduce memmap_alloc() to unify memory map allocation 2021-09-03 09:58:15 -07:00
swap_cgroup.c
swap_slots.c mm: Replace deprecated CPU-hotplug functions. 2021-08-28 01:46:17 +02:00
swap_state.c mm: swap: get rid of livelock in swapin readahead 2022-03-23 09:16:41 +01:00
swap.c mm: fs: invalidate bh_lrus for only cold path 2021-09-24 16:13:35 -07:00
swapfile.c mm, memcg: inline swap-related functions to improve disabled memcg config 2021-09-03 09:58:12 -07:00
truncate.c Merge branch 'akpm' (patches from Andrew) 2021-09-03 10:08:28 -07:00
usercopy.c mm/usercopy: return 1 from hardened_usercopy __setup() handler 2022-04-08 14:24:14 +02:00
userfaultfd.c userfaultfd: change mmap_changing to atomic 2021-09-03 09:58:16 -07:00
util.c mm: Consider __GFP_NOWARN flag for oversized kvmalloc() calls 2022-03-08 19:12:44 +01:00
vmacache.c
vmalloc.c mm: defer kmemleak object creation of module_alloc() 2022-03-08 19:12:38 +01:00
vmpressure.c mm/vmpressure: replace vmpressure_to_css() with vmpressure_to_memcg() 2021-09-03 09:58:17 -07:00
vmscan.c mm,vmscan: fix divide by zero in get_scan_count 2021-09-08 18:45:53 -07:00
vmstat.c mm/vmstat: protect per cpu variables with preempt disable on RT 2021-09-08 15:32:34 -07:00
workingset.c memcg: flush lruvec stats in the refault 2021-09-23 10:09:13 -07:00
z3fold.c mm/z3fold: add kerneldoc fields for z3fold_pool 2021-07-01 11:06:03 -07:00
zbud.c mm/zbud: add kerneldoc fields for zbud_pool 2021-07-01 11:06:03 -07:00
zpool.c mm: fix typos in comments 2021-05-07 00:26:35 -07:00
zsmalloc.c mm/zsmalloc.c: close race window between zs_pool_dec_isolated() and zs_unregister_migration() 2021-11-18 19:17:10 +01:00
zswap.c mm/zswap.c: fix two bugs in zswap_writeback_entry() 2021-06-30 20:47:31 -07:00