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cd197c3a20
linux/mm
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Barry Song cd197c3a20 mm: prohibit the last subpage from reusing the entire large folio 
In a Copy-on-Write (CoW) scenario, the last subpage will reuse the entire
large folio, resulting in the waste of (nr_pages - 1) pages.  This wasted
memory remains allocated until it is either unmapped or memory reclamation
occurs.

The following small program can serve as evidence of this behavior

 main()
 {
 #define SIZE 1024 * 1024 * 1024UL
         void *p = malloc(SIZE);
         memset(p, 0x11, SIZE);
         if (fork() == 0)
                 _exit(0);
         memset(p, 0x12, SIZE);
         printf("done\n");
         while(1);
 }

For example, using a 1024KiB mTHP by:
 echo always > /sys/kernel/mm/transparent_hugepage/hugepages-1024kB/enabled

(1) w/o the patch, it takes 2GiB,

Before running the test program,
 / # free -m
                total        used        free      shared  buff/cache   available
 Mem:            5754          84        5692           0          17        5669
 Swap:              0           0           0

 / # /a.out &
 / # done

After running the test program,
 / # free -m
                 total        used        free      shared  buff/cache   available
 Mem:            5754        2149        3627           0          19        3605
 Swap:              0           0           0

(2) w/ the patch, it takes 1GiB only,

Before running the test program,
 / # free -m
                 total        used        free      shared  buff/cache   available
 Mem:            5754          89        5687           0          17        5664
 Swap:              0           0           0

 / # /a.out &
 / # done

After running the test program,
 / # free -m
                total        used        free      shared  buff/cache   available
 Mem:            5754        1122        4655           0          17        4632
 Swap:              0           0           0

This patch migrates the last subpage to a small folio and immediately
returns the large folio to the system. It benefits both memory availability
and anti-fragmentation.

Link: https://lkml.kernel.org/r/20240308092721.144735-1-21cnbao@gmail.com
Signed-off-by: Barry Song <v-songbaohua@oppo.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Lance Yang <ioworker0@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2024-03-13 12:12:21 -07:00
..
damon mm: madvise: pageout: ignore references rather than clearing young 2024-03-04 17:01:18 -08:00
kasan mm/kasan: use pXd_leaf() in shadow_mapped() 2024-03-06 13:04:19 -08:00
kfence KFENCE: cleanup kfence_guarded_alloc() after CONFIG_SLAB removal 2023-12-05 11:17:58 +01:00
kmsan mm: kmsan: remove runtime checks from kmsan_unpoison_memory() 2024-02-22 10:24:41 -08:00
backing-dev.c blk-wbt: Fix detection of dirty-throttled tasks 2024-02-06 09:44:03 -07:00
balloon_compaction.c
bootmem_info.c bootmem: use kmemleak_free_part_phys in put_page_bootmem 2023-10-25 16:47:13 -07:00
cma_debug.c
cma_sysfs.c mm/cma: add sysfs file 'release_pages_success' 2024-02-22 10:24:57 -08:00
cma.c mm/cma: add sysfs file 'release_pages_success' 2024-02-22 10:24:57 -08:00
cma.h mm/cma: add sysfs file 'release_pages_success' 2024-02-22 10:24:57 -08:00
compaction.c mm/compaction: optimize >0 order folio compaction with free page split. 2024-02-23 17:48:33 -08:00
debug_page_alloc.c mm, treewide: rename MAX_ORDER to MAX_PAGE_ORDER 2024-01-08 15:27:15 -08:00
debug_page_ref.c
debug_vm_pgtable.c mm/debug_vm_pgtable: fix BUG_ON with pud advanced test 2024-02-23 17:27:13 -08:00
debug.c mm: make dump_page() take a const argument 2024-03-06 13:04:18 -08:00
dmapool_test.c
dmapool.c mm/mempool/dmapool: remove CONFIG_DEBUG_SLAB ifdefs 2023-12-05 11:17:58 +01:00
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 filemap: avoid unnecessary major faults in filemap_fault() 2024-03-06 13:04:20 -08:00
folio-compat.c mm: remove page_add_new_anon_rmap and lru_cache_add_inactive_or_unevictable 2023-12-29 11:58:27 -08:00
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
gup.c mm: convert page_try_share_anon_rmap() to folio_try_share_anon_rmap_[pte|pmd]() 2023-12-29 11:58:56 -08:00
highmem.c x86/kexec: use pr_err() instead of kexec_dprintk() when an error occurs 2023-12-29 12:22:28 -08:00
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/huge_memory: skip invalid debugfs new_order input for folio split 2024-03-12 13:07:17 -07:00
hugetlb_cgroup.c mm, hugetlb: remove HUGETLB_CGROUP_MIN_ORDER 2023-10-18 14:34:17 -07:00
hugetlb_vmemmap.c mm: hugetlb_vmemmap: move mmap lock to vmemmap_remap_range() 2023-12-12 10:57:08 -08:00
hugetlb_vmemmap.h mm: hugetlb_vmemmap: fix reference to nonexistent file 2023-10-25 16:47:14 -07:00
hugetlb.c mm: add an explicit smp_wmb() to UFFDIO_CONTINUE 2024-03-12 13:07:17 -07:00
hwpoison-inject.c
init-mm.c mm: Deprecate pasid field 2023-12-12 10:11:32 +01:00
internal.h mm: make folio_pte_batch available outside of mm/memory.c 2024-03-06 13:04:18 -08:00
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
Kconfig Introduce cpu_dcache_is_aliasing() across all architectures 2024-02-22 15:27:19 -08:00
Kconfig.debug mm/slab: remove CONFIG_SLAB from all Kconfig and Makefile 2023-12-05 11:14:40 +01:00
khugepaged.c mm: convert free_swap_cache() to take a folio 2024-03-04 17:01:26 -08:00
kmemleak.c kmemleak: avoid RCU stalls when freeing metadata for per-CPU pointers 2023-12-12 10:57:07 -08:00
ksm.c mm: convert page_try_share_anon_rmap() to folio_try_share_anon_rmap_[pte|pmd]() 2023-12-29 11:58:56 -08:00
list_lru.c mm/zswap: stop lru list shrinking when encounter warm region 2024-02-22 10:24:54 -08:00
maccess.c mm: Fix copy_from_user_nofault(). 2023-04-12 17:36:23 -07:00
madvise.c mm: madvise: pageout: ignore references rather than clearing young 2024-03-04 17:01:18 -08:00
Makefile mm/slab: remove CONFIG_SLAB from all Kconfig and Makefile 2023-12-05 11:14:40 +01:00
mapping_dirty_helpers.c mm: fix clean_record_shared_mapping_range kernel-doc 2023-08-24 16:20:30 -07:00
memblock.c mm/memblock: add MEMBLOCK_RSRV_NOINIT into flagname[] array 2024-02-20 14:20:49 -08:00
memcontrol.c memcg: remove mem_cgroup_uncharge_list() 2024-03-04 17:01:25 -08:00
memfd.c mm/memfd: refactor memfd_tag_pins() and memfd_wait_for_pins() 2024-03-04 17:01:21 -08:00
memory_hotplug.c mm/memory_hotplug: export mhp_supports_memmap_on_memory() 2024-02-22 10:24:40 -08:00
memory-failure.c mm/memory-failure: fix crash in split_huge_page_to_list from soft_offline_page 2024-02-07 21:20:34 -08:00
memory-tiers.c mm/demotion: print demotion targets 2024-02-22 10:24:55 -08:00
memory.c mm: prohibit the last subpage from reusing the entire large folio 2024-03-13 12:12:21 -07:00
mempolicy.c mm/mempolicy: use a folio in do_mbind() 2024-03-06 13:04:18 -08:00
mempool.c Many singleton patches against the MM code. The patch series which 2024-01-09 11:18:47 -08:00
memremap.c mm: remove stale example from comment 2023-12-29 11:58:26 -08:00
memtest.c mm: memtest: convert to memtest_report_meminfo() 2023-08-21 13:37:47 -07:00
migrate_device.c mm: convert page_try_share_anon_rmap() to folio_try_share_anon_rmap_[pte|pmd]() 2023-12-29 11:58:56 -08:00
migrate.c merge mm-hotfixes-stable into mm-nonmm-stable to pick up stackdepot changes 2024-02-23 17:28:43 -08:00
mincore.c mm: enable page walking API to lock vmas during the walk 2023-08-21 13:07:20 -07:00
mlock.c mm: make folios_put() the basis of release_pages() 2024-03-04 17:01:22 -08:00
mm_init.c Author: Gang Li padata: dispatch works on 2024-03-06 13:04:17 -08:00
mm_slot.h
mmap_lock.c
mmap.c mm/mmap: pass vma to vma_merge() 2024-02-22 10:24:52 -08:00
mmu_gather.c mm/mmu_gather: improve cond_resched() handling with large folios and expensive page freeing 2024-02-22 15:27:17 -08:00
mmu_notifier.c mmu_notifiers: rename invalidate_range notifier 2023-08-18 10:12:41 -07:00
mmzone.c zswap: shrink zswap pool based on memory pressure 2023-12-12 10:57:02 -08:00
mprotect.c mprotect: use pfn_swap_entry_folio 2024-02-21 16:00:03 -08:00
mremap.c mm: abstract VMA merge and extend into vma_merge_extend() helper 2023-10-18 14:34:18 -07:00
msync.c
nommu.c mm/vmalloc: remove vmap_area_list 2024-02-23 17:48:19 -08:00
oom_kill.c mm: update mark_victim tracepoints fields 2024-03-04 17:01:16 -08:00
page_alloc.c mm: page_alloc: use div64_ul() instead of do_div() 2024-03-06 13:04:18 -08:00
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
page_io.c zswap: memcontrol: implement zswap writeback disabling 2023-12-29 20:22:11 -08:00
page_isolation.c mm: add alloc_contig_migrate_range allocation statistics 2024-03-04 17:01:27 -08:00
page_owner.c mm,page_owner: drop unnecessary check 2024-03-06 13:04:20 -08:00
page_poison.c mm/page_poison: replace kmap_atomic() with kmap_local_page() 2023-12-10 16:51:50 -08:00
page_reporting.c mm, treewide: rename MAX_ORDER to MAX_PAGE_ORDER 2024-01-08 15:27:15 -08:00
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: thp: introduce multi-size THP sysfs interface 2023-12-20 14:48:12 -08:00
page-writeback.c writeback: remove a use of write_cache_pages() from do_writepages() 2024-02-23 17:48:38 -08:00
pagewalk.c mm: pagewalk: assert write mmap lock only for walking the user page tables 2023-12-10 16:51:53 -08:00
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: Introduce flush_cache_vmap_early() 2023-12-14 00:23:17 -08:00
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: fix process_vm_rw page counts 2023-12-10 16:51:39 -08:00
ptdump.c mm: ptdump: add check_wx_pages debugfs attribute 2024-02-22 10:24:47 -08:00
readahead.c mm: support order-1 folios in the page cache 2024-03-04 17:01:19 -08:00
rmap.c rmap: replace two calls to compound_order with folio_order 2024-02-22 15:27:20 -08:00
rodata_test.c
secretmem.c mm/secretmem: use a folio in secretmem_fault() 2023-08-21 13:38:02 -07:00
shmem_quota.c shmem: Add default quota limit mount options 2023-08-09 09:15:40 +02:00
shmem.c shmem: properly report quota mount options 2024-02-23 17:48:34 -08:00
show_mem.c mm, treewide: introduce NR_PAGE_ORDERS 2024-01-08 15:27:15 -08:00
shrinker_debug.c mm: shrinker: convert shrinker_rwsem to mutex 2023-10-04 10:32:26 -07:00
shrinker.c mm: shrinker: use kvzalloc_node() from expand_one_shrinker_info() 2024-01-05 09:58:32 -08:00
shuffle.c
shuffle.h mm, treewide: rename MAX_ORDER to MAX_PAGE_ORDER 2024-01-08 15:27:15 -08:00
slab_common.c slub: use a folio in __kmalloc_large_node 2024-01-05 10:17:46 -08:00
slab.h mm/slab: move kmalloc() functions from slab_common.c to slub.c 2023-12-06 11:57:21 +01:00
slub.c Many singleton patches against the MM code. The patch series which 2024-01-09 11:18:47 -08:00
sparse-vmemmap.c mm/vmemmap: allow architectures to override how vmemmap optimization works 2023-08-18 10:12:53 -07:00
sparse.c mm/memory_hotplug: introduce MEM_PREPARE_ONLINE/MEM_FINISH_OFFLINE notifiers 2024-02-21 16:00:01 -08:00
swap_cgroup.c
swap_slots.c mm/zswap: invalidate zswap entry when swap entry free 2024-02-22 10:24:54 -08:00
swap_state.c mm: convert free_swap_cache() to take a folio 2024-03-04 17:01:26 -08:00
swap.c mm: fix list corruption in put_pages_list 2024-03-12 13:07:16 -07:00
swap.h mm/swap: fix race when skipping swapcache 2024-02-20 14:20:48 -08:00
swapfile.c mm: swap: fix race between free_swap_and_cache() and swapoff() 2024-03-06 13:04:19 -08:00
truncate.c fs: convert error_remove_page to error_remove_folio 2023-12-10 16:51:42 -08:00
usercopy.c mm: Fix copy_from_user_nofault(). 2023-04-12 17:36:23 -07:00
userfaultfd.c mm: add an explicit smp_wmb() to UFFDIO_CONTINUE 2024-03-12 13:07:17 -07:00
util.c mm/util.c: add byte count to __vm_enough_memory failure warning 2024-03-04 17:01:14 -08:00
vmalloc.c mm: vmalloc: refactor vmalloc_dump_obj() function 2024-02-23 17:48:21 -08:00
vmpressure.c eventfd: simplify eventfd_signal() 2023-11-28 14:08:38 +01:00
vmscan.c mm, vmscan: retry kswapd's priority loop with cache_trim_mode off on failure 2024-03-12 13:07:17 -07:00
vmstat.c mm, treewide: rename MAX_ORDER to MAX_PAGE_ORDER 2024-01-08 15:27:15 -08:00
workingset.c mm: ratelimit stat flush from workingset shrinker 2024-01-05 10:17:45 -08:00
z3fold.c mm/z3fold: fix the comment for __encode_handle() 2024-02-23 17:48:31 -08:00
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 mm/zsmalloc: don't need to reserve LSB in handle 2024-03-04 17:01:28 -08:00
zswap.c mm/zswap: global lru and shrinker shared by all zswap_pools fix 2024-03-06 13:04:18 -08:00