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Hugh Dickins beb9868628 shmem,percpu_counter: add _limited_add(fbc, limit, amount) 
Percpu counter's compare and add are separate functions: without locking
around them (which would defeat their purpose), it has been possible to
overflow the intended limit.  Imagine all the other CPUs fallocating tmpfs
huge pages to the limit, in between this CPU's compare and its add.

I have not seen reports of that happening; but tmpfs's recent addition of
dquot_alloc_block_nodirty() in between the compare and the add makes it
even more likely, and I'd be uncomfortable to leave it unfixed.

Introduce percpu_counter_limited_add(fbc, limit, amount) to prevent it.

I believe this implementation is correct, and slightly more efficient than
the combination of compare and add (taking the lock once rather than twice
when nearing full - the last 128MiB of a tmpfs volume on a machine with
128 CPUs and 4KiB pages); but it does beg for a better design - when
nearing full, there is no new batching, but the costly percpu counter sum
across CPUs still has to be done, while locked.

Follow __percpu_counter_sum()'s example, including cpu_dying_mask as well
as cpu_online_mask: but shouldn't __percpu_counter_compare() and
__percpu_counter_limited_add() then be adding a num_dying_cpus() to
num_online_cpus(), when they calculate the maximum which could be held
across CPUs?  But the times when it matters would be vanishingly rare.

Link: https://lkml.kernel.org/r/bb817848-2d19-bcc8-39ca-ea179af0f0b4@google.com
Signed-off-by: Hugh Dickins <hughd@google.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Tim Chen <tim.c.chen@intel.com>
Cc: Dave Chinner <dchinner@redhat.com>
Cc: Darrick J. Wong <djwong@kernel.org>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Carlos Maiolino <cem@kernel.org>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Chuck Lever <chuck.lever@oracle.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 		2023-10-18 14:34:14 -07:00
..
damon Merge mm-hotfixes-stable into mm-stable to pick up depended-upon changes. 2023-10-18 14:32:58 -07:00
kasan kasan: disable kasan_non_canonical_hook() for HW tags 2023-10-18 12:12:41 -07:00
kfence LoongArch changes for v6.6 2023-09-08 12:16:52 -07:00
kmsan kmsan: introduce test_memcpy_initialized_gap() 2023-10-04 10:32:22 -07:00
Kconfig zswap: change zswap's default allocator to zsmalloc 2023-10-04 10:32:20 -07:00
Kconfig.debug mm: page_table_check: Make it dependent on EXCLUSIVE_SYSTEM_RAM 2023-05-29 16:14:28 +01:00
Makefile mm: vmscan: move shrinker-related code into a separate file 2023-10-04 10:32:23 -07:00
backing-dev.c writeback: remove redundant checks for root memcg 2023-08-21 13:37:48 -07:00
balloon_compaction.c
…
bootmem_info.c
…
cma.c mm/cma: use nth_page() in place of direct struct page manipulation 2023-10-04 10:32:29 -07:00
cma.h
…
cma_debug.c
…
cma_sysfs.c mm: cma: make kobj_type structure constant 2023-03-28 16:20:06 -07:00
compaction.c mm/compaction: factor out code to test if we should run compaction for target order 2023-10-04 10:32:19 -07:00
debug.c mm: update validate_mm() to use vma iterator 2023-06-09 16:25:31 -07:00
debug_page_alloc.c mm: page_alloc: split out DEBUG_PAGEALLOC 2023-06-09 16:25:23 -07:00
debug_page_ref.c
…
debug_vm_pgtable.c Add x86 shadow stack support 2023-08-31 12:20:12 -07:00
dmapool.c dmapool: create/destroy cleanup 2023-06-09 16:25:17 -07:00
dmapool_test.c dmapool: add alloc/free performance test 2023-04-05 19:42:38 -07:00
early_ioremap.c mm/early_ioremap.c: improve the execution efficiency of early_ioremap_setup() 2023-06-09 16:25:56 -07:00
fadvise.c mm: remove unnecessary pagevec includes 2023-06-23 16:59:31 -07:00
fail_page_alloc.c mm: page_alloc: split out FAIL_PAGE_ALLOC 2023-06-09 16:25:23 -07:00
failslab.c
…
filemap.c mm/filemap: clarify filemap_fault() comments for not uptodate case 2023-10-18 14:34:13 -07:00
folio-compat.c filemap: Add fgf_t typedef 2023-07-24 18:04:30 -04:00
gup.c Add x86 shadow stack support 2023-08-31 12:20:12 -07:00
gup_test.c Merge mm-hotfixes-stable into mm-stable to pick up depended-upon changes. 2023-06-23 16:58:19 -07:00
gup_test.h
…
highmem.c mm: ptep_get() conversion 2023-06-19 16:19:25 -07:00
hmm.c mm: enable page walking API to lock vmas during the walk 2023-08-21 13:07:20 -07:00
huge_memory.c mm: memory: make numa_migrate_prep() to take a folio 2023-10-16 15:44:37 -07:00
hugetlb.c fs/proc/task_mmu: implement IOCTL to get and optionally clear info about PTEs 2023-10-18 14:34:12 -07:00
hugetlb_cgroup.c mm/hugetlb: increase use of folios in alloc_huge_page() 2023-02-13 15:54:27 -08:00
hugetlb_vmemmap.c mm: hugetlb: skip initialization of gigantic tail struct pages if freed by HVO 2023-10-04 10:32:30 -07:00
hugetlb_vmemmap.h mm: hugetlb: skip initialization of gigantic tail struct pages if freed by HVO 2023-10-04 10:32:30 -07:00
hwpoison-inject.c
…
init-mm.c mm: move dummy_vm_ops out of a header 2023-08-21 13:37:46 -07:00
internal.h mm: memory: make numa_migrate_prep() to take a folio 2023-10-16 15:44:37 -07:00
interval_tree.c
…
io-mapping.c
…
ioremap.c mm: ioremap: remove unneeded ioremap_allowed and iounmap_allowed 2023-08-18 10:12:36 -07:00
khugepaged.c - Some swap cleanups from Ma Wupeng ("fix WARN_ON in add_to_avail_list") 2023-08-29 14:25:26 -07:00
kmemleak.c mm/kmemleak: move up cond_resched() call in page scanning loop 2023-09-02 15:17:34 -07:00
ksm.c mm/ksm: add pages_skipped metric 2023-10-16 15:44:39 -07:00
list_lru.c
…
maccess.c mm: Fix copy_from_user_nofault(). 2023-04-12 17:36:23 -07:00
madvise.c mm: remove remnants of SPLIT_RSS_COUNTING 2023-10-04 10:32:20 -07:00
mapping_dirty_helpers.c mm: fix clean_record_shared_mapping_range kernel-doc 2023-08-24 16:20:30 -07:00
memblock.c memblock: introduce MEMBLOCK_RSRV_NOINIT flag 2023-10-04 10:32:30 -07:00
memcontrol.c mm: memcg: normalize the value passed into memcg_rstat_updated() 2023-10-18 14:34:12 -07:00
memfd.c memfd: drop warning for missing exec-related flags 2023-10-04 10:32:22 -07:00
memory-failure.c mm: convert DAX lock/unlock page to lock/unlock folio 2023-10-04 10:32:20 -07:00
memory-tiers.c dax, kmem: calculate abstract distance with general interface 2023-10-16 15:44:39 -07:00
memory.c userfaultfd: UFFD_FEATURE_WP_ASYNC 2023-10-18 14:34:12 -07:00
memory_hotplug.c mm/memory_hotplug: use pfn math in place of direct struct page manipulation 2023-10-04 10:32:29 -07:00
mempolicy.c Merge mm-hotfixes-stable into mm-stable to pick up depended-upon changes. 2023-10-18 14:32:58 -07:00
mempool.c
…
memremap.c mm/memremap.c: fix outdated comment in devm_memremap_pages 2023-02-09 16:51:46 -08:00
memtest.c mm: memtest: convert to memtest_report_meminfo() 2023-08-21 13:37:47 -07:00
migrate.c Merge mm-hotfixes-stable into mm-stable to pick up depended-upon changes. 2023-10-18 14:32:58 -07:00
migrate_device.c Add x86 shadow stack support 2023-08-31 12:20:12 -07:00
mincore.c mm: enable page walking API to lock vmas during the walk 2023-08-21 13:07:20 -07:00
mlock.c mm: mlock: update mlock_pte_range to handle large folio 2023-10-04 10:32:32 -07:00
mm_init.c mm: hugetlb: skip initialization of gigantic tail struct pages if freed by HVO 2023-10-04 10:32:30 -07:00
mm_slot.h
…
mmap.c Merge mm-hotfixes-stable into mm-stable to pick up depended-upon changes. 2023-10-18 14:32:58 -07:00
mmap_lock.c
…
mmu_gather.c mm: fix kernel-doc warning from tlb_flush_rmaps() 2023-08-24 16:20:30 -07:00
mmu_notifier.c mmu_notifiers: rename invalidate_range notifier 2023-08-18 10:12:41 -07:00
mmzone.c
…
mprotect.c Add x86 shadow stack support 2023-08-31 12:20:12 -07:00
mremap.c mm/mremap: allow moves within the same VMA for stack moves 2023-10-04 10:32:20 -07:00
msync.c
…
nommu.c Add x86 shadow stack support 2023-08-31 12:20:12 -07:00
oom_kill.c mm: remove redundant K() macro definition 2023-08-21 13:37:44 -07:00
page-writeback.c mm/writeback: update filemap_dirty_folio() comment 2023-10-04 10:32:32 -07:00
page_alloc.c mm/page_alloc: correct start page when guard page debug is enabled 2023-10-06 14:11:38 -07:00
page_counter.c
…
page_ext.c mm/page_ext: move functions around for minor cleanups to page_ext 2023-08-18 10:12:31 -07:00
page_idle.c mm: page_idle: convert page idle to use a folio 2023-01-18 17:12:52 -08:00
page_io.c mm: memcg: add THP swap out info for anonymous reclaim 2023-10-04 10:32:27 -07:00
page_isolation.c mm/hugetlb: get rid of page_hstate() 2023-08-18 10:12:39 -07:00
page_owner.c mm/page_ext: use page_ext_data helper in page_owner 2023-08-21 13:37:27 -07:00
page_poison.c mm/page_poison: remove unused page_ext.h from page_poison 2023-08-21 13:37:30 -07:00
page_reporting.c mm, treewide: redefine MAX_ORDER sanely 2023-04-05 19:42:46 -07:00
page_reporting.h
…
page_table_check.c mm: convert page_table_check_pte_set() to page_table_check_ptes_set() 2023-08-24 16:20:18 -07:00
page_vma_mapped.c mm: correct stale comment of function check_pte 2023-08-18 10:12:13 -07:00
pagewalk.c mm/pagewalk: fix bootstopping regression from extra pte_unmap() 2023-09-02 08:39:21 -07:00
percpu-internal.h percpu-internal/pcpu_chunk: re-layout pcpu_chunk structure to reduce false sharing 2023-06-19 16:19:29 -07:00
percpu-km.c
…
percpu-stats.c
…
percpu-vm.c
…
percpu.c mm/percpu.c: print error message too if atomic alloc failed 2023-08-25 08:04:59 -07:00
pgalloc-track.h
…
pgtable-generic.c mm/pgtable: notes on pte_offset_map[_lock]() 2023-08-18 10:12:25 -07:00
process_vm_access.c mm/gup: remove unused vmas parameter from pin_user_pages_remote() 2023-06-09 16:25:25 -07:00
ptdump.c mm: ptdump should use ptep_get_lockless() 2023-06-19 16:19:24 -07:00
readahead.c filemap: Allow __filemap_get_folio to allocate large folios 2023-07-24 18:04:30 -04:00
rmap.c mm: handle large folio when large folio in VM_LOCKED VMA range 2023-10-04 10:32:32 -07:00
rodata_test.c
…
secretmem.c mm/secretmem: use a folio in secretmem_fault() 2023-08-21 13:38:02 -07:00
shmem.c shmem,percpu_counter: add _limited_add(fbc, limit, amount) 2023-10-18 14:34:14 -07:00
shmem_quota.c shmem: Add default quota limit mount options 2023-08-09 09:15:40 +02:00
show_mem.c mm: refactor si_mem_available() 2023-10-04 10:32:19 -07:00
shrinker.c mm: shrinker: convert shrinker_rwsem to mutex 2023-10-04 10:32:26 -07:00
shrinker_debug.c mm: shrinker: convert shrinker_rwsem to mutex 2023-10-04 10:32:26 -07:00
shuffle.c
…
shuffle.h mm, treewide: redefine MAX_ORDER sanely 2023-04-05 19:42:46 -07:00
slab.c Randomized slab caches for kmalloc() 2023-07-18 10:07:47 +02:00
slab.h Randomized slab caches for kmalloc() 2023-07-18 10:07:47 +02:00
slab_common.c slab fixes for 6.6-rc4 2023-09-29 12:10:12 -07:00
slub.c mm/slub: remove freelist_dereference() 2023-07-14 09:57:21 +02:00
sparse-vmemmap.c mm/vmemmap: allow architectures to override how vmemmap optimization works 2023-08-18 10:12:53 -07:00
sparse.c mm/sparse: remove redundant judgments from macro for_each_present_section_nr 2023-08-18 10:12:14 -07:00
swap.c mm: remove references to pagevec 2023-06-23 16:59:30 -07:00
swap.h swap: remove remnants of polling from read_swap_cache_async 2023-08-24 16:20:16 -07:00
swap_cgroup.c
…
swap_slots.c
…
swap_state.c mm/swap: inline folio_set_swap_entry() and folio_swap_entry() 2023-08-24 16:20:28 -07:00
swapfile.c mm/swap: inline folio_set_swap_entry() and folio_swap_entry() 2023-08-24 16:20:28 -07:00
truncate.c - Some swap cleanups from Ma Wupeng ("fix WARN_ON in add_to_avail_list") 2023-08-29 14:25:26 -07:00
usercopy.c mm: Fix copy_from_user_nofault(). 2023-04-12 17:36:23 -07:00
userfaultfd.c Add x86 shadow stack support 2023-08-31 12:20:12 -07:00
util.c rcu: dump vmalloc memory info safely 2023-09-05 10:13:45 -07:00
vmalloc.c mm: hugetlb: add huge page size param to set_huge_pte_at() 2023-09-29 17:20:47 -07:00
vmpressure.c net-memcg: Fix scope of sockmem pressure indicators 2023-08-16 12:21:32 +01:00
vmscan.c delayacct: add memory reclaim delay in get_page_from_freelist 2023-10-06 14:44:10 -07:00
vmstat.c mm/vmstat: use this_cpu_try_cmpxchg in mod_{zone,node}_state 2023-10-04 10:32:20 -07:00
workingset.c mm: workingset: dynamically allocate the mm-shadow shrinker 2023-10-04 10:32:24 -07:00
z3fold.c mm/z3fold: remove obsolete comment for struct z3fold_pool 2023-08-21 13:37:51 -07:00
zbud.c mm: zswap: remove shrink from zpool interface 2023-06-19 16:19:27 -07:00
zpool.c mm: zswap: remove shrink from zpool interface 2023-06-19 16:19:27 -07:00
zsmalloc.c zsmalloc: dynamically allocate the mm-zspool shrinker 2023-10-04 10:32:26 -07:00
zswap.c mm: zswap: fix pool refcount bug around shrink_worker() 2023-10-18 12:12:40 -07:00