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linux/mm
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Barry Song c18160dba5 mm: swap: reuse exclusive folio directly instead of wp page faults 
After swapping out, we perform a swap-in operation.  If we first read and
then write, we encounter a major fault in do_swap_page for reading, along
with additional minor faults in do_wp_page for writing.  However, the
latter appears to be unnecessary and inefficient.  Instead, we can
directly reuse in do_swap_page and completely eliminate the need for
do_wp_page.

This patch achieves that optimization specifically for exclusive folios. 
The following microbenchmark demonstrates the significant reduction in
minor faults.

 #define DATA_SIZE (2UL * 1024 * 1024)
 #define PAGE_SIZE (4UL * 1024)

 static void *read_write_data(char *addr)
 {
         char tmp;

         for (int i = 0; i < DATA_SIZE; i += PAGE_SIZE) {
                 tmp = *(volatile char *)(addr + i);
                 *(volatile char *)(addr + i) = tmp;
         }
 }

 int main(int argc, char **argv)
 {
         struct rusage ru;

         char *addr = mmap(NULL, DATA_SIZE, PROT_READ | PROT_WRITE,
                         MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
         memset(addr, 0x11, DATA_SIZE);

         do {
                 long old_ru_minflt, old_ru_majflt;
                 long new_ru_minflt, new_ru_majflt;

                 madvise(addr, DATA_SIZE, MADV_PAGEOUT);

                 getrusage(RUSAGE_SELF, &ru);
                 old_ru_minflt = ru.ru_minflt;
                 old_ru_majflt = ru.ru_majflt;

                 read_write_data(addr);
                 getrusage(RUSAGE_SELF, &ru);
                 new_ru_minflt = ru.ru_minflt;
                 new_ru_majflt = ru.ru_majflt;

                 printf("minor faults:%ld major faults:%ld\n",
                         new_ru_minflt - old_ru_minflt,
                         new_ru_majflt - old_ru_majflt);
         } while(0);

         return 0;
 }

w/o patch,
/ # ~/a.out
minor faults:512 major faults:512

w/ patch,
/ # ~/a.out
minor faults:0 major faults:512

Minor faults decrease to 0!

Link: https://lkml.kernel.org/r/20240602004502.26895-1-21cnbao@gmail.com
Signed-off-by: Barry Song <v-songbaohua@oppo.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Chris Li <chrisl@kernel.org>
Cc: Kairui Song <kasong@tencent.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2024-07-03 19:30:04 -07:00
..
damon mm/damon/core: fix return value from damos_wmark_metric_value 2024-05-11 15:41:36 -07:00
kasan kasan: fix bad call to unpoison_slab_object 2024-06-24 20:52:09 -07:00
kfence mm/kfence: add MODULE_DESCRIPTION() 2024-07-03 19:29:58 -07:00
kmsan kmsan: introduce test_unpoison_memory() 2024-07-03 19:30:02 -07:00
backing-dev.c writeback: support retrieving per group debug writeback stats of bdi 2024-05-05 17:53:51 -07:00
balloon_compaction.c mm: remove MIGRATE_SYNC_NO_COPY mode 2024-07-03 19:30:00 -07:00
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: drop incorrect alignment check in cma_init_reserved_mem 2024-04-25 20:56:42 -07:00
cma.h mm/cma: add sysfs file 'release_pages_success' 2024-02-22 10:24:57 -08:00
compaction.c mm: handle profiling for fake memory allocations during compaction 2024-06-24 20:52:09 -07:00
debug_page_alloc.c mm: page_alloc: consolidate free page accounting 2024-04-25 20:56:04 -07:00
debug_page_ref.c
debug_vm_pgtable.c mm/debug_vm_pgtable: drop RANDOM_ORVALUE trick 2024-06-15 10:43:08 -07:00
debug.c mm/debug: print only page mapcount (excluding folio entire mapcount) in __dump_folio() 2024-05-05 17:53:31 -07:00
dmapool_test.c mm/dmapool: add MODULE_DESCRIPTION() 2024-07-03 19:29:58 -07:00
dmapool.c mm/mempool/dmapool: remove CONFIG_DEBUG_SLAB ifdefs 2023-12-05 11:17:58 +01:00
early_ioremap.c
execmem.c mm/execmem, arch: convert remaining overrides of module_alloc to execmem 2024-05-14 00:31:43 -07:00
fadvise.c
fail_page_alloc.c
failslab.c
filemap.c mm: fix xyz_noprof functions calling profiled functions 2024-06-05 19:19:26 -07:00
folio-compat.c mm: remove page_mapping() 2024-07-03 19:29:59 -07:00
gup_test.c
gup_test.h
gup.c mm/gup: fix hugepd handling in hugetlb rework 2024-05-07 10:37:01 -07:00
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/treewide: replace pXd_huge() with pXd_leaf() 2024-04-25 20:55:46 -07:00
huge_memory.c mm: shmem: add mTHP counters for anonymous shmem 2024-07-03 19:30:04 -07:00
hugetlb_cgroup.c mm/hugetlb: assert hugetlb_lock in __hugetlb_cgroup_commit_charge 2024-05-05 17:53:41 -07:00
hugetlb_vmemmap.c memory: remove the now superfluous sentinel element from ctl_table array 2024-04-25 20:56:32 -07:00
hugetlb_vmemmap.h mm: hugetlb_vmemmap: fix reference to nonexistent file 2023-10-25 16:47:14 -07:00
hugetlb.c mm/hugetlb: drop node_alloc_noretry from alloc_fresh_hugetlb_folio 2024-07-03 19:29:52 -07:00
hwpoison-inject.c mm/hwpoison: add MODULE_DESCRIPTION() 2024-07-03 19:29:58 -07:00
init-mm.c mm: Deprecate pasid field 2023-12-12 10:11:32 +01:00
internal.h mm: introduce pte_move_swp_offset() helper which can move offset bidirectionally 2024-07-03 19:30:01 -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
Kconfig The usual shower of singleton fixes and minor series all over MM, 2024-05-19 09:21:03 -07:00
Kconfig.debug mm/slub: unify all sl[au]b parameters with "slab_$param" 2024-01-22 10:31:08 +01:00
khugepaged.c mm: simplify thp_vma_allowable_order 2024-05-05 17:53:53 -07:00
kmemleak.c mm: lift gfp_kmemleak_mask() to gfp.h 2024-05-19 14:40:44 -07:00
ksm.c mm/ksm: fix ksm_zero_pages accounting 2024-06-05 19:19:26 -07:00
list_lru.c mm/zswap: stop lru list shrinking when encounter warm region 2024-02-22 10:24:54 -08:00
maccess.c
madvise.c mm/madvise: add MF_ACTION_REQUIRED to madvise(MADV_HWPOISON) 2024-07-03 19:29:57 -07:00
Makefile mseal: add mseal syscall 2024-05-23 19:40:26 -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: use numa_valid_node() helper to check for invalid node ID 2024-06-16 10:17:57 +03:00
memcontrol.c mm: memcontrol: remove page_memcg() 2024-07-03 19:29:59 -07:00
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: drop memblock_phys_free() call in try_remove_memory() 2024-07-03 19:30:04 -07:00
memory-failure.c mm/memory-failure: stop setting the folio error flag 2024-07-03 19:30:03 -07:00
memory-tiers.c memory tier: create CPUless memory tiers after obtaining HMAT info 2024-05-05 17:53:26 -07:00
memory.c mm: swap: reuse exclusive folio directly instead of wp page faults 2024-07-03 19:30:04 -07:00
mempolicy.c mm: mempolicy: use folio_alloc_mpol() in alloc_migration_target_by_mpol() 2024-07-03 19:29:53 -07:00
mempool.c mm: fix xyz_noprof functions calling profiled functions 2024-06-05 19:19:26 -07:00
memremap.c mm: convert put_devmap_managed_page_refs() to put_devmap_managed_folio_refs() 2024-05-05 17:53:49 -07:00
memtest.c memtest: use {READ,WRITE}_ONCE in memory scanning 2024-03-13 12:12:21 -07:00
migrate_device.c mm: migrate_device: unify migrate folio for MIGRATE_SYNC_NO_COPY 2024-07-03 19:30:00 -07:00
migrate.c mm: remove MIGRATE_SYNC_NO_COPY mode 2024-07-03 19:30:00 -07:00
mincore.c mm/swap: reduce swap cache search space 2024-07-03 19:29:56 -07:00
mlock.c mm: add pmd_folio() 2024-04-25 20:56:19 -07:00
mm_init.c mm/mm_init: use node's number of cpus in deferred_page_init_max_threads 2024-07-03 19:29:58 -07:00
mm_slot.h
mmap_lock.c
mmap.c mm: batch unlink_file_vma calls in free_pgd_range 2024-07-03 19:29:58 -07:00
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_notifier: remove the .change_pte() callback 2024-04-11 13:18:36 -04:00
mmzone.c zswap: shrink zswap pool based on memory pressure 2023-12-12 10:57:02 -08:00
mprotect.c mm/memory: cleanly support zeropage in vm_insert_page*(), vm_map_pages*() and vmf_insert_mixed() 2024-07-03 19:29:56 -07:00
mremap.c mseal: add mseal syscall 2024-05-23 19:40:26 -07:00
mseal.c mseal: add mseal syscall 2024-05-23 19:40:26 -07:00
msync.c
nommu.c The usual shower of singleton fixes and minor series all over MM, 2024-05-19 09:21:03 -07:00
oom_kill.c memory: remove the now superfluous sentinel element from ctl_table array 2024-04-25 20:56:32 -07:00
page_alloc.c mm/page_alloc: Separate THP PCP into movable and non-movable categories 2024-06-24 20:52:11 -07:00
page_counter.c
page_ext.c mm: make page_ext_get() take a const argument 2024-04-25 20:56:14 -07:00
page_idle.c
page_io.c mm/swap: get the swap device offset directly 2024-07-03 19:29:55 -07:00
page_isolation.c mm: page_isolation: prepare for hygienic freelists 2024-04-25 20:56:04 -07:00
page_owner.c mm/page-owner: use gfp_nested_mask() instead of open coded masking 2024-05-19 14:40:44 -07:00
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/page_table_check: fix crash on ZONE_DEVICE 2024-06-15 10:43:04 -07:00
page_vma_mapped.c mm: make page_mapped_in_vma conditional on CONFIG_MEMORY_FAILURE 2024-05-05 17:53:45 -07:00
page-writeback.c writeback: factor out balance_wb_limits to remove repeated code 2024-07-03 19:29:54 -07:00
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 mm: percpu: add codetag reference into pcpuobj_ext 2024-04-25 20:55:56 -07:00
percpu-km.c
percpu-stats.c
percpu-vm.c percpu: clean up all mappings when pcpu_map_pages() fails 2024-04-25 20:55:49 -07:00
percpu.c mm: percpu: enable per-cpu allocation tagging 2024-04-25 20:55:56 -07:00
pgalloc-track.h
pgtable-generic.c mm: fix race between __split_huge_pmd_locked() and GUP-fast 2024-05-07 10:37:00 -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 The usual shower of singleton fixes and minor series all over MM, 2024-05-19 09:21:03 -07:00
rmap.c mm: rmap: abstract updating per-node and per-memcg stats 2024-07-03 19:30:01 -07:00
rodata_test.c
secretmem.c mm/secretmem: use a folio in secretmem_fault() 2023-08-21 13:38:02 -07:00
shmem_quota.c tmpfs: fix race on handling dquot rbtree 2024-03-26 11:07:23 -07:00
shmem.c mm: shmem: add mTHP counters for anonymous shmem 2024-07-03 19:30:04 -07:00
show_mem.c lib: add memory allocations report in show_mem() 2024-04-25 20:55:57 -07:00
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 The usual shower of singleton fixes and minor series all over MM, 2024-05-19 09:21:03 -07:00
slab.h The usual shower of singleton fixes and minor series all over MM, 2024-05-19 09:21:03 -07:00
slub.c mm/slab: fix 'variable obj_exts set but not used' warning 2024-06-24 20:52:09 -07:00
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: consistently use _nr 2024-07-03 19:30:02 -07:00
swap_cgroup.c
swap_slots.c mm: swap: update get_swap_pages() to take folio order 2024-04-25 20:56:37 -07:00
swap_state.c mm,swap: simplify VMA based swap readahead window calculation 2024-07-03 19:30:03 -07:00
swap.c mm: add kernel-doc for folio_mark_accessed() 2024-05-05 17:53:50 -07:00
swap.h mm/swap: reduce swap cache search space 2024-07-03 19:29:56 -07:00
swapfile.c mm: remove the implementation of swap_free() and always use swap_free_nr() 2024-07-03 19:30:01 -07:00
truncate.c mm/vmscan: update stale references to shrink_page_list 2024-07-03 19:29:52 -07:00
usercopy.c
userfaultfd.c mm: userfaultfd: use swap() in double_pt_lock() 2024-07-03 19:30:03 -07:00
util.c hardening fixes for v6.10-rc5 2024-06-17 12:00:22 -07:00
vmalloc.c mm/vmalloc: use __this_cpu_try_cmpxchg() in preload_this_cpu_lock() 2024-07-03 19:30:02 -07:00
vmpressure.c eventfd: simplify eventfd_signal() 2023-11-28 14:08:38 +01:00
vmscan.c mm: vmscan: reset sc->priority on retry 2024-07-03 19:29:53 -07:00
vmstat.c iommu: observability of the IOMMU allocations 2024-04-15 14:31:47 +02:00
workingset.c mm: cleanup WORKINGSET_NODES in workingset 2024-05-07 10:36:59 -07:00
z3fold.c mm: zpool: return pool size in pages 2024-04-25 20:55:48 -07:00
zbud.c mm: zpool: return pool size in pages 2024-04-25 20:55:48 -07:00
zpool.c mm: zpool: return pool size in pages 2024-04-25 20:55:48 -07:00
zsmalloc.c mm: remove MIGRATE_SYNC_NO_COPY mode 2024-07-03 19:30:00 -07:00
zswap.c mm: zswap: make same_filled functions folio-friendly 2024-07-03 19:30:00 -07:00