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2618 lines
70 KiB
C
2618 lines
70 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Memory Migration functionality - linux/mm/migrate.c
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*
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* Copyright (C) 2006 Silicon Graphics, Inc., Christoph Lameter
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*
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* Page migration was first developed in the context of the memory hotplug
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* project. The main authors of the migration code are:
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*
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* IWAMOTO Toshihiro <iwamoto@valinux.co.jp>
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* Hirokazu Takahashi <taka@valinux.co.jp>
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* Dave Hansen <haveblue@us.ibm.com>
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* Christoph Lameter
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*/
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#include <linux/migrate.h>
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#include <linux/export.h>
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#include <linux/swap.h>
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#include <linux/swapops.h>
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#include <linux/pagemap.h>
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#include <linux/buffer_head.h>
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#include <linux/mm_inline.h>
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#include <linux/nsproxy.h>
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#include <linux/ksm.h>
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#include <linux/rmap.h>
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#include <linux/topology.h>
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#include <linux/cpu.h>
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#include <linux/cpuset.h>
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#include <linux/writeback.h>
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#include <linux/mempolicy.h>
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#include <linux/vmalloc.h>
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#include <linux/security.h>
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#include <linux/backing-dev.h>
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#include <linux/compaction.h>
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#include <linux/syscalls.h>
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#include <linux/compat.h>
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#include <linux/hugetlb.h>
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#include <linux/hugetlb_cgroup.h>
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#include <linux/gfp.h>
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#include <linux/pfn_t.h>
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#include <linux/memremap.h>
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#include <linux/userfaultfd_k.h>
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#include <linux/balloon_compaction.h>
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#include <linux/page_idle.h>
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#include <linux/page_owner.h>
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#include <linux/sched/mm.h>
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#include <linux/ptrace.h>
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#include <linux/oom.h>
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#include <linux/memory.h>
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#include <linux/random.h>
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#include <linux/sched/sysctl.h>
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#include <linux/memory-tiers.h>
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#include <asm/tlbflush.h>
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#include <trace/events/migrate.h>
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#include "internal.h"
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bool isolate_movable_page(struct page *page, isolate_mode_t mode)
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{
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struct folio *folio = folio_get_nontail_page(page);
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const struct movable_operations *mops;
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/*
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* Avoid burning cycles with pages that are yet under __free_pages(),
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* or just got freed under us.
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*
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* In case we 'win' a race for a movable page being freed under us and
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* raise its refcount preventing __free_pages() from doing its job
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* the put_page() at the end of this block will take care of
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* release this page, thus avoiding a nasty leakage.
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*/
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if (!folio)
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goto out;
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if (unlikely(folio_test_slab(folio)))
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goto out_putfolio;
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/* Pairs with smp_wmb() in slab freeing, e.g. SLUB's __free_slab() */
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smp_rmb();
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/*
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* Check movable flag before taking the page lock because
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* we use non-atomic bitops on newly allocated page flags so
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* unconditionally grabbing the lock ruins page's owner side.
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*/
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if (unlikely(!__folio_test_movable(folio)))
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goto out_putfolio;
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/* Pairs with smp_wmb() in slab allocation, e.g. SLUB's alloc_slab_page() */
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smp_rmb();
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if (unlikely(folio_test_slab(folio)))
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goto out_putfolio;
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/*
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* As movable pages are not isolated from LRU lists, concurrent
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* compaction threads can race against page migration functions
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* as well as race against the releasing a page.
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*
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* In order to avoid having an already isolated movable page
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* being (wrongly) re-isolated while it is under migration,
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* or to avoid attempting to isolate pages being released,
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* lets be sure we have the page lock
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* before proceeding with the movable page isolation steps.
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*/
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if (unlikely(!folio_trylock(folio)))
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goto out_putfolio;
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if (!folio_test_movable(folio) || folio_test_isolated(folio))
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goto out_no_isolated;
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mops = folio_movable_ops(folio);
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VM_BUG_ON_FOLIO(!mops, folio);
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if (!mops->isolate_page(&folio->page, mode))
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goto out_no_isolated;
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/* Driver shouldn't use PG_isolated bit of page->flags */
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WARN_ON_ONCE(folio_test_isolated(folio));
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folio_set_isolated(folio);
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folio_unlock(folio);
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return true;
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out_no_isolated:
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folio_unlock(folio);
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out_putfolio:
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folio_put(folio);
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out:
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return false;
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}
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static void putback_movable_folio(struct folio *folio)
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{
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const struct movable_operations *mops = folio_movable_ops(folio);
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mops->putback_page(&folio->page);
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folio_clear_isolated(folio);
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}
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/*
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* Put previously isolated pages back onto the appropriate lists
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* from where they were once taken off for compaction/migration.
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*
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* This function shall be used whenever the isolated pageset has been
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* built from lru, balloon, hugetlbfs page. See isolate_migratepages_range()
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* and isolate_hugetlb().
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*/
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void putback_movable_pages(struct list_head *l)
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{
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struct folio *folio;
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struct folio *folio2;
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list_for_each_entry_safe(folio, folio2, l, lru) {
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if (unlikely(folio_test_hugetlb(folio))) {
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folio_putback_active_hugetlb(folio);
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continue;
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}
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list_del(&folio->lru);
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/*
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* We isolated non-lru movable folio so here we can use
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* __folio_test_movable because LRU folio's mapping cannot
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* have PAGE_MAPPING_MOVABLE.
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*/
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if (unlikely(__folio_test_movable(folio))) {
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VM_BUG_ON_FOLIO(!folio_test_isolated(folio), folio);
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folio_lock(folio);
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if (folio_test_movable(folio))
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putback_movable_folio(folio);
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else
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folio_clear_isolated(folio);
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folio_unlock(folio);
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folio_put(folio);
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} else {
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node_stat_mod_folio(folio, NR_ISOLATED_ANON +
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folio_is_file_lru(folio), -folio_nr_pages(folio));
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folio_putback_lru(folio);
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}
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}
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}
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/*
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* Restore a potential migration pte to a working pte entry
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*/
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static bool remove_migration_pte(struct folio *folio,
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struct vm_area_struct *vma, unsigned long addr, void *old)
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{
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DEFINE_FOLIO_VMA_WALK(pvmw, old, vma, addr, PVMW_SYNC | PVMW_MIGRATION);
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while (page_vma_mapped_walk(&pvmw)) {
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rmap_t rmap_flags = RMAP_NONE;
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pte_t old_pte;
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pte_t pte;
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swp_entry_t entry;
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struct page *new;
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unsigned long idx = 0;
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/* pgoff is invalid for ksm pages, but they are never large */
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if (folio_test_large(folio) && !folio_test_hugetlb(folio))
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idx = linear_page_index(vma, pvmw.address) - pvmw.pgoff;
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new = folio_page(folio, idx);
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#ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
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/* PMD-mapped THP migration entry */
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if (!pvmw.pte) {
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VM_BUG_ON_FOLIO(folio_test_hugetlb(folio) ||
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!folio_test_pmd_mappable(folio), folio);
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remove_migration_pmd(&pvmw, new);
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continue;
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}
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#endif
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folio_get(folio);
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pte = mk_pte(new, READ_ONCE(vma->vm_page_prot));
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old_pte = ptep_get(pvmw.pte);
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entry = pte_to_swp_entry(old_pte);
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if (!is_migration_entry_young(entry))
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pte = pte_mkold(pte);
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if (folio_test_dirty(folio) && is_migration_entry_dirty(entry))
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pte = pte_mkdirty(pte);
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if (pte_swp_soft_dirty(old_pte))
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pte = pte_mksoft_dirty(pte);
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else
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pte = pte_clear_soft_dirty(pte);
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if (is_writable_migration_entry(entry))
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pte = pte_mkwrite(pte, vma);
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else if (pte_swp_uffd_wp(old_pte))
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pte = pte_mkuffd_wp(pte);
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if (folio_test_anon(folio) && !is_readable_migration_entry(entry))
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rmap_flags |= RMAP_EXCLUSIVE;
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if (unlikely(is_device_private_page(new))) {
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if (pte_write(pte))
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entry = make_writable_device_private_entry(
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page_to_pfn(new));
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else
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entry = make_readable_device_private_entry(
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page_to_pfn(new));
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pte = swp_entry_to_pte(entry);
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if (pte_swp_soft_dirty(old_pte))
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pte = pte_swp_mksoft_dirty(pte);
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if (pte_swp_uffd_wp(old_pte))
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pte = pte_swp_mkuffd_wp(pte);
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}
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#ifdef CONFIG_HUGETLB_PAGE
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if (folio_test_hugetlb(folio)) {
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struct hstate *h = hstate_vma(vma);
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unsigned int shift = huge_page_shift(h);
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unsigned long psize = huge_page_size(h);
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pte = arch_make_huge_pte(pte, shift, vma->vm_flags);
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if (folio_test_anon(folio))
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hugetlb_add_anon_rmap(folio, vma, pvmw.address,
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rmap_flags);
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else
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hugetlb_add_file_rmap(folio);
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set_huge_pte_at(vma->vm_mm, pvmw.address, pvmw.pte, pte,
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psize);
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} else
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#endif
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{
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if (folio_test_anon(folio))
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folio_add_anon_rmap_pte(folio, new, vma,
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pvmw.address, rmap_flags);
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else
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folio_add_file_rmap_pte(folio, new, vma);
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set_pte_at(vma->vm_mm, pvmw.address, pvmw.pte, pte);
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}
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if (vma->vm_flags & VM_LOCKED)
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mlock_drain_local();
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trace_remove_migration_pte(pvmw.address, pte_val(pte),
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compound_order(new));
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/* No need to invalidate - it was non-present before */
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update_mmu_cache(vma, pvmw.address, pvmw.pte);
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}
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return true;
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}
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/*
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* Get rid of all migration entries and replace them by
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* references to the indicated page.
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*/
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void remove_migration_ptes(struct folio *src, struct folio *dst, bool locked)
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{
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struct rmap_walk_control rwc = {
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.rmap_one = remove_migration_pte,
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.arg = src,
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};
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if (locked)
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rmap_walk_locked(dst, &rwc);
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else
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rmap_walk(dst, &rwc);
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}
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/*
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* Something used the pte of a page under migration. We need to
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* get to the page and wait until migration is finished.
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* When we return from this function the fault will be retried.
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*/
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void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd,
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unsigned long address)
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{
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spinlock_t *ptl;
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pte_t *ptep;
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pte_t pte;
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swp_entry_t entry;
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ptep = pte_offset_map_lock(mm, pmd, address, &ptl);
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if (!ptep)
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return;
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pte = ptep_get(ptep);
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pte_unmap(ptep);
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if (!is_swap_pte(pte))
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goto out;
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entry = pte_to_swp_entry(pte);
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if (!is_migration_entry(entry))
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goto out;
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migration_entry_wait_on_locked(entry, ptl);
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return;
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out:
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spin_unlock(ptl);
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}
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#ifdef CONFIG_HUGETLB_PAGE
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/*
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* The vma read lock must be held upon entry. Holding that lock prevents either
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* the pte or the ptl from being freed.
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*
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* This function will release the vma lock before returning.
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*/
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void migration_entry_wait_huge(struct vm_area_struct *vma, pte_t *ptep)
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{
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spinlock_t *ptl = huge_pte_lockptr(hstate_vma(vma), vma->vm_mm, ptep);
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pte_t pte;
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hugetlb_vma_assert_locked(vma);
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spin_lock(ptl);
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pte = huge_ptep_get(ptep);
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if (unlikely(!is_hugetlb_entry_migration(pte))) {
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spin_unlock(ptl);
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hugetlb_vma_unlock_read(vma);
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} else {
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/*
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* If migration entry existed, safe to release vma lock
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* here because the pgtable page won't be freed without the
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* pgtable lock released. See comment right above pgtable
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* lock release in migration_entry_wait_on_locked().
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*/
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hugetlb_vma_unlock_read(vma);
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migration_entry_wait_on_locked(pte_to_swp_entry(pte), ptl);
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}
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}
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#endif
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#ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
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void pmd_migration_entry_wait(struct mm_struct *mm, pmd_t *pmd)
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{
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spinlock_t *ptl;
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ptl = pmd_lock(mm, pmd);
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if (!is_pmd_migration_entry(*pmd))
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goto unlock;
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migration_entry_wait_on_locked(pmd_to_swp_entry(*pmd), ptl);
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return;
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unlock:
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spin_unlock(ptl);
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}
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#endif
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static int folio_expected_refs(struct address_space *mapping,
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struct folio *folio)
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{
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int refs = 1;
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if (!mapping)
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return refs;
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refs += folio_nr_pages(folio);
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if (folio_test_private(folio))
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refs++;
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return refs;
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}
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/*
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* Replace the page in the mapping.
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*
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* The number of remaining references must be:
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* 1 for anonymous pages without a mapping
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* 2 for pages with a mapping
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* 3 for pages with a mapping and PagePrivate/PagePrivate2 set.
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*/
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int folio_migrate_mapping(struct address_space *mapping,
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struct folio *newfolio, struct folio *folio, int extra_count)
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{
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XA_STATE(xas, &mapping->i_pages, folio_index(folio));
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struct zone *oldzone, *newzone;
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int dirty;
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int expected_count = folio_expected_refs(mapping, folio) + extra_count;
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long nr = folio_nr_pages(folio);
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long entries, i;
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if (!mapping) {
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/* Anonymous page without mapping */
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if (folio_ref_count(folio) != expected_count)
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return -EAGAIN;
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/* No turning back from here */
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newfolio->index = folio->index;
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newfolio->mapping = folio->mapping;
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if (folio_test_swapbacked(folio))
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__folio_set_swapbacked(newfolio);
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return MIGRATEPAGE_SUCCESS;
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}
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oldzone = folio_zone(folio);
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newzone = folio_zone(newfolio);
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xas_lock_irq(&xas);
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if (!folio_ref_freeze(folio, expected_count)) {
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xas_unlock_irq(&xas);
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return -EAGAIN;
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}
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/*
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* Now we know that no one else is looking at the folio:
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* no turning back from here.
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*/
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newfolio->index = folio->index;
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newfolio->mapping = folio->mapping;
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folio_ref_add(newfolio, nr); /* add cache reference */
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if (folio_test_swapbacked(folio)) {
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__folio_set_swapbacked(newfolio);
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if (folio_test_swapcache(folio)) {
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folio_set_swapcache(newfolio);
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newfolio->private = folio_get_private(folio);
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}
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entries = nr;
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} else {
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VM_BUG_ON_FOLIO(folio_test_swapcache(folio), folio);
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entries = 1;
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}
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/* Move dirty while page refs frozen and newpage not yet exposed */
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dirty = folio_test_dirty(folio);
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if (dirty) {
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folio_clear_dirty(folio);
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folio_set_dirty(newfolio);
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}
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/* Swap cache still stores N entries instead of a high-order entry */
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for (i = 0; i < entries; i++) {
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xas_store(&xas, newfolio);
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xas_next(&xas);
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}
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/*
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* Drop cache reference from old page by unfreezing
|
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* to one less reference.
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* We know this isn't the last reference.
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*/
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folio_ref_unfreeze(folio, expected_count - nr);
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|
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xas_unlock(&xas);
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/* Leave irq disabled to prevent preemption while updating stats */
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|
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/*
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* If moved to a different zone then also account
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* the page for that zone. Other VM counters will be
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* taken care of when we establish references to the
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* new page and drop references to the old page.
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*
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* Note that anonymous pages are accounted for
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* via NR_FILE_PAGES and NR_ANON_MAPPED if they
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* are mapped to swap space.
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*/
|
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if (newzone != oldzone) {
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struct lruvec *old_lruvec, *new_lruvec;
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struct mem_cgroup *memcg;
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memcg = folio_memcg(folio);
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old_lruvec = mem_cgroup_lruvec(memcg, oldzone->zone_pgdat);
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new_lruvec = mem_cgroup_lruvec(memcg, newzone->zone_pgdat);
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|
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__mod_lruvec_state(old_lruvec, NR_FILE_PAGES, -nr);
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__mod_lruvec_state(new_lruvec, NR_FILE_PAGES, nr);
|
|
if (folio_test_swapbacked(folio) && !folio_test_swapcache(folio)) {
|
|
__mod_lruvec_state(old_lruvec, NR_SHMEM, -nr);
|
|
__mod_lruvec_state(new_lruvec, NR_SHMEM, nr);
|
|
|
|
if (folio_test_pmd_mappable(folio)) {
|
|
__mod_lruvec_state(old_lruvec, NR_SHMEM_THPS, -nr);
|
|
__mod_lruvec_state(new_lruvec, NR_SHMEM_THPS, nr);
|
|
}
|
|
}
|
|
#ifdef CONFIG_SWAP
|
|
if (folio_test_swapcache(folio)) {
|
|
__mod_lruvec_state(old_lruvec, NR_SWAPCACHE, -nr);
|
|
__mod_lruvec_state(new_lruvec, NR_SWAPCACHE, nr);
|
|
}
|
|
#endif
|
|
if (dirty && mapping_can_writeback(mapping)) {
|
|
__mod_lruvec_state(old_lruvec, NR_FILE_DIRTY, -nr);
|
|
__mod_zone_page_state(oldzone, NR_ZONE_WRITE_PENDING, -nr);
|
|
__mod_lruvec_state(new_lruvec, NR_FILE_DIRTY, nr);
|
|
__mod_zone_page_state(newzone, NR_ZONE_WRITE_PENDING, nr);
|
|
}
|
|
}
|
|
local_irq_enable();
|
|
|
|
return MIGRATEPAGE_SUCCESS;
|
|
}
|
|
EXPORT_SYMBOL(folio_migrate_mapping);
|
|
|
|
/*
|
|
* The expected number of remaining references is the same as that
|
|
* of folio_migrate_mapping().
|
|
*/
|
|
int migrate_huge_page_move_mapping(struct address_space *mapping,
|
|
struct folio *dst, struct folio *src)
|
|
{
|
|
XA_STATE(xas, &mapping->i_pages, folio_index(src));
|
|
int expected_count;
|
|
|
|
xas_lock_irq(&xas);
|
|
expected_count = folio_expected_refs(mapping, src);
|
|
if (!folio_ref_freeze(src, expected_count)) {
|
|
xas_unlock_irq(&xas);
|
|
return -EAGAIN;
|
|
}
|
|
|
|
dst->index = src->index;
|
|
dst->mapping = src->mapping;
|
|
|
|
folio_ref_add(dst, folio_nr_pages(dst));
|
|
|
|
xas_store(&xas, dst);
|
|
|
|
folio_ref_unfreeze(src, expected_count - folio_nr_pages(src));
|
|
|
|
xas_unlock_irq(&xas);
|
|
|
|
return MIGRATEPAGE_SUCCESS;
|
|
}
|
|
|
|
/*
|
|
* Copy the flags and some other ancillary information
|
|
*/
|
|
void folio_migrate_flags(struct folio *newfolio, struct folio *folio)
|
|
{
|
|
int cpupid;
|
|
|
|
if (folio_test_error(folio))
|
|
folio_set_error(newfolio);
|
|
if (folio_test_referenced(folio))
|
|
folio_set_referenced(newfolio);
|
|
if (folio_test_uptodate(folio))
|
|
folio_mark_uptodate(newfolio);
|
|
if (folio_test_clear_active(folio)) {
|
|
VM_BUG_ON_FOLIO(folio_test_unevictable(folio), folio);
|
|
folio_set_active(newfolio);
|
|
} else if (folio_test_clear_unevictable(folio))
|
|
folio_set_unevictable(newfolio);
|
|
if (folio_test_workingset(folio))
|
|
folio_set_workingset(newfolio);
|
|
if (folio_test_checked(folio))
|
|
folio_set_checked(newfolio);
|
|
/*
|
|
* PG_anon_exclusive (-> PG_mappedtodisk) is always migrated via
|
|
* migration entries. We can still have PG_anon_exclusive set on an
|
|
* effectively unmapped and unreferenced first sub-pages of an
|
|
* anonymous THP: we can simply copy it here via PG_mappedtodisk.
|
|
*/
|
|
if (folio_test_mappedtodisk(folio))
|
|
folio_set_mappedtodisk(newfolio);
|
|
|
|
/* Move dirty on pages not done by folio_migrate_mapping() */
|
|
if (folio_test_dirty(folio))
|
|
folio_set_dirty(newfolio);
|
|
|
|
if (folio_test_young(folio))
|
|
folio_set_young(newfolio);
|
|
if (folio_test_idle(folio))
|
|
folio_set_idle(newfolio);
|
|
|
|
/*
|
|
* Copy NUMA information to the new page, to prevent over-eager
|
|
* future migrations of this same page.
|
|
*/
|
|
cpupid = folio_xchg_last_cpupid(folio, -1);
|
|
/*
|
|
* For memory tiering mode, when migrate between slow and fast
|
|
* memory node, reset cpupid, because that is used to record
|
|
* page access time in slow memory node.
|
|
*/
|
|
if (sysctl_numa_balancing_mode & NUMA_BALANCING_MEMORY_TIERING) {
|
|
bool f_toptier = node_is_toptier(folio_nid(folio));
|
|
bool t_toptier = node_is_toptier(folio_nid(newfolio));
|
|
|
|
if (f_toptier != t_toptier)
|
|
cpupid = -1;
|
|
}
|
|
folio_xchg_last_cpupid(newfolio, cpupid);
|
|
|
|
folio_migrate_ksm(newfolio, folio);
|
|
/*
|
|
* Please do not reorder this without considering how mm/ksm.c's
|
|
* get_ksm_page() depends upon ksm_migrate_page() and PageSwapCache().
|
|
*/
|
|
if (folio_test_swapcache(folio))
|
|
folio_clear_swapcache(folio);
|
|
folio_clear_private(folio);
|
|
|
|
/* page->private contains hugetlb specific flags */
|
|
if (!folio_test_hugetlb(folio))
|
|
folio->private = NULL;
|
|
|
|
/*
|
|
* If any waiters have accumulated on the new page then
|
|
* wake them up.
|
|
*/
|
|
if (folio_test_writeback(newfolio))
|
|
folio_end_writeback(newfolio);
|
|
|
|
/*
|
|
* PG_readahead shares the same bit with PG_reclaim. The above
|
|
* end_page_writeback() may clear PG_readahead mistakenly, so set the
|
|
* bit after that.
|
|
*/
|
|
if (folio_test_readahead(folio))
|
|
folio_set_readahead(newfolio);
|
|
|
|
folio_copy_owner(newfolio, folio);
|
|
|
|
mem_cgroup_migrate(folio, newfolio);
|
|
}
|
|
EXPORT_SYMBOL(folio_migrate_flags);
|
|
|
|
void folio_migrate_copy(struct folio *newfolio, struct folio *folio)
|
|
{
|
|
folio_copy(newfolio, folio);
|
|
folio_migrate_flags(newfolio, folio);
|
|
}
|
|
EXPORT_SYMBOL(folio_migrate_copy);
|
|
|
|
/************************************************************
|
|
* Migration functions
|
|
***********************************************************/
|
|
|
|
int migrate_folio_extra(struct address_space *mapping, struct folio *dst,
|
|
struct folio *src, enum migrate_mode mode, int extra_count)
|
|
{
|
|
int rc;
|
|
|
|
BUG_ON(folio_test_writeback(src)); /* Writeback must be complete */
|
|
|
|
rc = folio_migrate_mapping(mapping, dst, src, extra_count);
|
|
|
|
if (rc != MIGRATEPAGE_SUCCESS)
|
|
return rc;
|
|
|
|
if (mode != MIGRATE_SYNC_NO_COPY)
|
|
folio_migrate_copy(dst, src);
|
|
else
|
|
folio_migrate_flags(dst, src);
|
|
return MIGRATEPAGE_SUCCESS;
|
|
}
|
|
|
|
/**
|
|
* migrate_folio() - Simple folio migration.
|
|
* @mapping: The address_space containing the folio.
|
|
* @dst: The folio to migrate the data to.
|
|
* @src: The folio containing the current data.
|
|
* @mode: How to migrate the page.
|
|
*
|
|
* Common logic to directly migrate a single LRU folio suitable for
|
|
* folios that do not use PagePrivate/PagePrivate2.
|
|
*
|
|
* Folios are locked upon entry and exit.
|
|
*/
|
|
int migrate_folio(struct address_space *mapping, struct folio *dst,
|
|
struct folio *src, enum migrate_mode mode)
|
|
{
|
|
return migrate_folio_extra(mapping, dst, src, mode, 0);
|
|
}
|
|
EXPORT_SYMBOL(migrate_folio);
|
|
|
|
#ifdef CONFIG_BUFFER_HEAD
|
|
/* Returns true if all buffers are successfully locked */
|
|
static bool buffer_migrate_lock_buffers(struct buffer_head *head,
|
|
enum migrate_mode mode)
|
|
{
|
|
struct buffer_head *bh = head;
|
|
struct buffer_head *failed_bh;
|
|
|
|
do {
|
|
if (!trylock_buffer(bh)) {
|
|
if (mode == MIGRATE_ASYNC)
|
|
goto unlock;
|
|
if (mode == MIGRATE_SYNC_LIGHT && !buffer_uptodate(bh))
|
|
goto unlock;
|
|
lock_buffer(bh);
|
|
}
|
|
|
|
bh = bh->b_this_page;
|
|
} while (bh != head);
|
|
|
|
return true;
|
|
|
|
unlock:
|
|
/* We failed to lock the buffer and cannot stall. */
|
|
failed_bh = bh;
|
|
bh = head;
|
|
while (bh != failed_bh) {
|
|
unlock_buffer(bh);
|
|
bh = bh->b_this_page;
|
|
}
|
|
|
|
return false;
|
|
}
|
|
|
|
static int __buffer_migrate_folio(struct address_space *mapping,
|
|
struct folio *dst, struct folio *src, enum migrate_mode mode,
|
|
bool check_refs)
|
|
{
|
|
struct buffer_head *bh, *head;
|
|
int rc;
|
|
int expected_count;
|
|
|
|
head = folio_buffers(src);
|
|
if (!head)
|
|
return migrate_folio(mapping, dst, src, mode);
|
|
|
|
/* Check whether page does not have extra refs before we do more work */
|
|
expected_count = folio_expected_refs(mapping, src);
|
|
if (folio_ref_count(src) != expected_count)
|
|
return -EAGAIN;
|
|
|
|
if (!buffer_migrate_lock_buffers(head, mode))
|
|
return -EAGAIN;
|
|
|
|
if (check_refs) {
|
|
bool busy;
|
|
bool invalidated = false;
|
|
|
|
recheck_buffers:
|
|
busy = false;
|
|
spin_lock(&mapping->i_private_lock);
|
|
bh = head;
|
|
do {
|
|
if (atomic_read(&bh->b_count)) {
|
|
busy = true;
|
|
break;
|
|
}
|
|
bh = bh->b_this_page;
|
|
} while (bh != head);
|
|
if (busy) {
|
|
if (invalidated) {
|
|
rc = -EAGAIN;
|
|
goto unlock_buffers;
|
|
}
|
|
spin_unlock(&mapping->i_private_lock);
|
|
invalidate_bh_lrus();
|
|
invalidated = true;
|
|
goto recheck_buffers;
|
|
}
|
|
}
|
|
|
|
rc = folio_migrate_mapping(mapping, dst, src, 0);
|
|
if (rc != MIGRATEPAGE_SUCCESS)
|
|
goto unlock_buffers;
|
|
|
|
folio_attach_private(dst, folio_detach_private(src));
|
|
|
|
bh = head;
|
|
do {
|
|
folio_set_bh(bh, dst, bh_offset(bh));
|
|
bh = bh->b_this_page;
|
|
} while (bh != head);
|
|
|
|
if (mode != MIGRATE_SYNC_NO_COPY)
|
|
folio_migrate_copy(dst, src);
|
|
else
|
|
folio_migrate_flags(dst, src);
|
|
|
|
rc = MIGRATEPAGE_SUCCESS;
|
|
unlock_buffers:
|
|
if (check_refs)
|
|
spin_unlock(&mapping->i_private_lock);
|
|
bh = head;
|
|
do {
|
|
unlock_buffer(bh);
|
|
bh = bh->b_this_page;
|
|
} while (bh != head);
|
|
|
|
return rc;
|
|
}
|
|
|
|
/**
|
|
* buffer_migrate_folio() - Migration function for folios with buffers.
|
|
* @mapping: The address space containing @src.
|
|
* @dst: The folio to migrate to.
|
|
* @src: The folio to migrate from.
|
|
* @mode: How to migrate the folio.
|
|
*
|
|
* This function can only be used if the underlying filesystem guarantees
|
|
* that no other references to @src exist. For example attached buffer
|
|
* heads are accessed only under the folio lock. If your filesystem cannot
|
|
* provide this guarantee, buffer_migrate_folio_norefs() may be more
|
|
* appropriate.
|
|
*
|
|
* Return: 0 on success or a negative errno on failure.
|
|
*/
|
|
int buffer_migrate_folio(struct address_space *mapping,
|
|
struct folio *dst, struct folio *src, enum migrate_mode mode)
|
|
{
|
|
return __buffer_migrate_folio(mapping, dst, src, mode, false);
|
|
}
|
|
EXPORT_SYMBOL(buffer_migrate_folio);
|
|
|
|
/**
|
|
* buffer_migrate_folio_norefs() - Migration function for folios with buffers.
|
|
* @mapping: The address space containing @src.
|
|
* @dst: The folio to migrate to.
|
|
* @src: The folio to migrate from.
|
|
* @mode: How to migrate the folio.
|
|
*
|
|
* Like buffer_migrate_folio() except that this variant is more careful
|
|
* and checks that there are also no buffer head references. This function
|
|
* is the right one for mappings where buffer heads are directly looked
|
|
* up and referenced (such as block device mappings).
|
|
*
|
|
* Return: 0 on success or a negative errno on failure.
|
|
*/
|
|
int buffer_migrate_folio_norefs(struct address_space *mapping,
|
|
struct folio *dst, struct folio *src, enum migrate_mode mode)
|
|
{
|
|
return __buffer_migrate_folio(mapping, dst, src, mode, true);
|
|
}
|
|
EXPORT_SYMBOL_GPL(buffer_migrate_folio_norefs);
|
|
#endif /* CONFIG_BUFFER_HEAD */
|
|
|
|
int filemap_migrate_folio(struct address_space *mapping,
|
|
struct folio *dst, struct folio *src, enum migrate_mode mode)
|
|
{
|
|
int ret;
|
|
|
|
ret = folio_migrate_mapping(mapping, dst, src, 0);
|
|
if (ret != MIGRATEPAGE_SUCCESS)
|
|
return ret;
|
|
|
|
if (folio_get_private(src))
|
|
folio_attach_private(dst, folio_detach_private(src));
|
|
|
|
if (mode != MIGRATE_SYNC_NO_COPY)
|
|
folio_migrate_copy(dst, src);
|
|
else
|
|
folio_migrate_flags(dst, src);
|
|
return MIGRATEPAGE_SUCCESS;
|
|
}
|
|
EXPORT_SYMBOL_GPL(filemap_migrate_folio);
|
|
|
|
/*
|
|
* Writeback a folio to clean the dirty state
|
|
*/
|
|
static int writeout(struct address_space *mapping, struct folio *folio)
|
|
{
|
|
struct writeback_control wbc = {
|
|
.sync_mode = WB_SYNC_NONE,
|
|
.nr_to_write = 1,
|
|
.range_start = 0,
|
|
.range_end = LLONG_MAX,
|
|
.for_reclaim = 1
|
|
};
|
|
int rc;
|
|
|
|
if (!mapping->a_ops->writepage)
|
|
/* No write method for the address space */
|
|
return -EINVAL;
|
|
|
|
if (!folio_clear_dirty_for_io(folio))
|
|
/* Someone else already triggered a write */
|
|
return -EAGAIN;
|
|
|
|
/*
|
|
* A dirty folio may imply that the underlying filesystem has
|
|
* the folio on some queue. So the folio must be clean for
|
|
* migration. Writeout may mean we lose the lock and the
|
|
* folio state is no longer what we checked for earlier.
|
|
* At this point we know that the migration attempt cannot
|
|
* be successful.
|
|
*/
|
|
remove_migration_ptes(folio, folio, false);
|
|
|
|
rc = mapping->a_ops->writepage(&folio->page, &wbc);
|
|
|
|
if (rc != AOP_WRITEPAGE_ACTIVATE)
|
|
/* unlocked. Relock */
|
|
folio_lock(folio);
|
|
|
|
return (rc < 0) ? -EIO : -EAGAIN;
|
|
}
|
|
|
|
/*
|
|
* Default handling if a filesystem does not provide a migration function.
|
|
*/
|
|
static int fallback_migrate_folio(struct address_space *mapping,
|
|
struct folio *dst, struct folio *src, enum migrate_mode mode)
|
|
{
|
|
if (folio_test_dirty(src)) {
|
|
/* Only writeback folios in full synchronous migration */
|
|
switch (mode) {
|
|
case MIGRATE_SYNC:
|
|
case MIGRATE_SYNC_NO_COPY:
|
|
break;
|
|
default:
|
|
return -EBUSY;
|
|
}
|
|
return writeout(mapping, src);
|
|
}
|
|
|
|
/*
|
|
* Buffers may be managed in a filesystem specific way.
|
|
* We must have no buffers or drop them.
|
|
*/
|
|
if (!filemap_release_folio(src, GFP_KERNEL))
|
|
return mode == MIGRATE_SYNC ? -EAGAIN : -EBUSY;
|
|
|
|
return migrate_folio(mapping, dst, src, mode);
|
|
}
|
|
|
|
/*
|
|
* Move a page to a newly allocated page
|
|
* The page is locked and all ptes have been successfully removed.
|
|
*
|
|
* The new page will have replaced the old page if this function
|
|
* is successful.
|
|
*
|
|
* Return value:
|
|
* < 0 - error code
|
|
* MIGRATEPAGE_SUCCESS - success
|
|
*/
|
|
static int move_to_new_folio(struct folio *dst, struct folio *src,
|
|
enum migrate_mode mode)
|
|
{
|
|
int rc = -EAGAIN;
|
|
bool is_lru = !__folio_test_movable(src);
|
|
|
|
VM_BUG_ON_FOLIO(!folio_test_locked(src), src);
|
|
VM_BUG_ON_FOLIO(!folio_test_locked(dst), dst);
|
|
|
|
if (likely(is_lru)) {
|
|
struct address_space *mapping = folio_mapping(src);
|
|
|
|
if (!mapping)
|
|
rc = migrate_folio(mapping, dst, src, mode);
|
|
else if (mapping_unmovable(mapping))
|
|
rc = -EOPNOTSUPP;
|
|
else if (mapping->a_ops->migrate_folio)
|
|
/*
|
|
* Most folios have a mapping and most filesystems
|
|
* provide a migrate_folio callback. Anonymous folios
|
|
* are part of swap space which also has its own
|
|
* migrate_folio callback. This is the most common path
|
|
* for page migration.
|
|
*/
|
|
rc = mapping->a_ops->migrate_folio(mapping, dst, src,
|
|
mode);
|
|
else
|
|
rc = fallback_migrate_folio(mapping, dst, src, mode);
|
|
} else {
|
|
const struct movable_operations *mops;
|
|
|
|
/*
|
|
* In case of non-lru page, it could be released after
|
|
* isolation step. In that case, we shouldn't try migration.
|
|
*/
|
|
VM_BUG_ON_FOLIO(!folio_test_isolated(src), src);
|
|
if (!folio_test_movable(src)) {
|
|
rc = MIGRATEPAGE_SUCCESS;
|
|
folio_clear_isolated(src);
|
|
goto out;
|
|
}
|
|
|
|
mops = folio_movable_ops(src);
|
|
rc = mops->migrate_page(&dst->page, &src->page, mode);
|
|
WARN_ON_ONCE(rc == MIGRATEPAGE_SUCCESS &&
|
|
!folio_test_isolated(src));
|
|
}
|
|
|
|
/*
|
|
* When successful, old pagecache src->mapping must be cleared before
|
|
* src is freed; but stats require that PageAnon be left as PageAnon.
|
|
*/
|
|
if (rc == MIGRATEPAGE_SUCCESS) {
|
|
if (__folio_test_movable(src)) {
|
|
VM_BUG_ON_FOLIO(!folio_test_isolated(src), src);
|
|
|
|
/*
|
|
* We clear PG_movable under page_lock so any compactor
|
|
* cannot try to migrate this page.
|
|
*/
|
|
folio_clear_isolated(src);
|
|
}
|
|
|
|
/*
|
|
* Anonymous and movable src->mapping will be cleared by
|
|
* free_pages_prepare so don't reset it here for keeping
|
|
* the type to work PageAnon, for example.
|
|
*/
|
|
if (!folio_mapping_flags(src))
|
|
src->mapping = NULL;
|
|
|
|
if (likely(!folio_is_zone_device(dst)))
|
|
flush_dcache_folio(dst);
|
|
}
|
|
out:
|
|
return rc;
|
|
}
|
|
|
|
/*
|
|
* To record some information during migration, we use unused private
|
|
* field of struct folio of the newly allocated destination folio.
|
|
* This is safe because nobody is using it except us.
|
|
*/
|
|
enum {
|
|
PAGE_WAS_MAPPED = BIT(0),
|
|
PAGE_WAS_MLOCKED = BIT(1),
|
|
PAGE_OLD_STATES = PAGE_WAS_MAPPED | PAGE_WAS_MLOCKED,
|
|
};
|
|
|
|
static void __migrate_folio_record(struct folio *dst,
|
|
int old_page_state,
|
|
struct anon_vma *anon_vma)
|
|
{
|
|
dst->private = (void *)anon_vma + old_page_state;
|
|
}
|
|
|
|
static void __migrate_folio_extract(struct folio *dst,
|
|
int *old_page_state,
|
|
struct anon_vma **anon_vmap)
|
|
{
|
|
unsigned long private = (unsigned long)dst->private;
|
|
|
|
*anon_vmap = (struct anon_vma *)(private & ~PAGE_OLD_STATES);
|
|
*old_page_state = private & PAGE_OLD_STATES;
|
|
dst->private = NULL;
|
|
}
|
|
|
|
/* Restore the source folio to the original state upon failure */
|
|
static void migrate_folio_undo_src(struct folio *src,
|
|
int page_was_mapped,
|
|
struct anon_vma *anon_vma,
|
|
bool locked,
|
|
struct list_head *ret)
|
|
{
|
|
if (page_was_mapped)
|
|
remove_migration_ptes(src, src, false);
|
|
/* Drop an anon_vma reference if we took one */
|
|
if (anon_vma)
|
|
put_anon_vma(anon_vma);
|
|
if (locked)
|
|
folio_unlock(src);
|
|
if (ret)
|
|
list_move_tail(&src->lru, ret);
|
|
}
|
|
|
|
/* Restore the destination folio to the original state upon failure */
|
|
static void migrate_folio_undo_dst(struct folio *dst, bool locked,
|
|
free_folio_t put_new_folio, unsigned long private)
|
|
{
|
|
if (locked)
|
|
folio_unlock(dst);
|
|
if (put_new_folio)
|
|
put_new_folio(dst, private);
|
|
else
|
|
folio_put(dst);
|
|
}
|
|
|
|
/* Cleanup src folio upon migration success */
|
|
static void migrate_folio_done(struct folio *src,
|
|
enum migrate_reason reason)
|
|
{
|
|
/*
|
|
* Compaction can migrate also non-LRU pages which are
|
|
* not accounted to NR_ISOLATED_*. They can be recognized
|
|
* as __folio_test_movable
|
|
*/
|
|
if (likely(!__folio_test_movable(src)))
|
|
mod_node_page_state(folio_pgdat(src), NR_ISOLATED_ANON +
|
|
folio_is_file_lru(src), -folio_nr_pages(src));
|
|
|
|
if (reason != MR_MEMORY_FAILURE)
|
|
/* We release the page in page_handle_poison. */
|
|
folio_put(src);
|
|
}
|
|
|
|
/* Obtain the lock on page, remove all ptes. */
|
|
static int migrate_folio_unmap(new_folio_t get_new_folio,
|
|
free_folio_t put_new_folio, unsigned long private,
|
|
struct folio *src, struct folio **dstp, enum migrate_mode mode,
|
|
enum migrate_reason reason, struct list_head *ret)
|
|
{
|
|
struct folio *dst;
|
|
int rc = -EAGAIN;
|
|
int old_page_state = 0;
|
|
struct anon_vma *anon_vma = NULL;
|
|
bool is_lru = !__folio_test_movable(src);
|
|
bool locked = false;
|
|
bool dst_locked = false;
|
|
|
|
if (folio_ref_count(src) == 1) {
|
|
/* Folio was freed from under us. So we are done. */
|
|
folio_clear_active(src);
|
|
folio_clear_unevictable(src);
|
|
/* free_pages_prepare() will clear PG_isolated. */
|
|
list_del(&src->lru);
|
|
migrate_folio_done(src, reason);
|
|
return MIGRATEPAGE_SUCCESS;
|
|
}
|
|
|
|
dst = get_new_folio(src, private);
|
|
if (!dst)
|
|
return -ENOMEM;
|
|
*dstp = dst;
|
|
|
|
dst->private = NULL;
|
|
|
|
if (!folio_trylock(src)) {
|
|
if (mode == MIGRATE_ASYNC)
|
|
goto out;
|
|
|
|
/*
|
|
* It's not safe for direct compaction to call lock_page.
|
|
* For example, during page readahead pages are added locked
|
|
* to the LRU. Later, when the IO completes the pages are
|
|
* marked uptodate and unlocked. However, the queueing
|
|
* could be merging multiple pages for one bio (e.g.
|
|
* mpage_readahead). If an allocation happens for the
|
|
* second or third page, the process can end up locking
|
|
* the same page twice and deadlocking. Rather than
|
|
* trying to be clever about what pages can be locked,
|
|
* avoid the use of lock_page for direct compaction
|
|
* altogether.
|
|
*/
|
|
if (current->flags & PF_MEMALLOC)
|
|
goto out;
|
|
|
|
/*
|
|
* In "light" mode, we can wait for transient locks (eg
|
|
* inserting a page into the page table), but it's not
|
|
* worth waiting for I/O.
|
|
*/
|
|
if (mode == MIGRATE_SYNC_LIGHT && !folio_test_uptodate(src))
|
|
goto out;
|
|
|
|
folio_lock(src);
|
|
}
|
|
locked = true;
|
|
if (folio_test_mlocked(src))
|
|
old_page_state |= PAGE_WAS_MLOCKED;
|
|
|
|
if (folio_test_writeback(src)) {
|
|
/*
|
|
* Only in the case of a full synchronous migration is it
|
|
* necessary to wait for PageWriteback. In the async case,
|
|
* the retry loop is too short and in the sync-light case,
|
|
* the overhead of stalling is too much
|
|
*/
|
|
switch (mode) {
|
|
case MIGRATE_SYNC:
|
|
case MIGRATE_SYNC_NO_COPY:
|
|
break;
|
|
default:
|
|
rc = -EBUSY;
|
|
goto out;
|
|
}
|
|
folio_wait_writeback(src);
|
|
}
|
|
|
|
/*
|
|
* By try_to_migrate(), src->mapcount goes down to 0 here. In this case,
|
|
* we cannot notice that anon_vma is freed while we migrate a page.
|
|
* This get_anon_vma() delays freeing anon_vma pointer until the end
|
|
* of migration. File cache pages are no problem because of page_lock()
|
|
* File Caches may use write_page() or lock_page() in migration, then,
|
|
* just care Anon page here.
|
|
*
|
|
* Only folio_get_anon_vma() understands the subtleties of
|
|
* getting a hold on an anon_vma from outside one of its mms.
|
|
* But if we cannot get anon_vma, then we won't need it anyway,
|
|
* because that implies that the anon page is no longer mapped
|
|
* (and cannot be remapped so long as we hold the page lock).
|
|
*/
|
|
if (folio_test_anon(src) && !folio_test_ksm(src))
|
|
anon_vma = folio_get_anon_vma(src);
|
|
|
|
/*
|
|
* Block others from accessing the new page when we get around to
|
|
* establishing additional references. We are usually the only one
|
|
* holding a reference to dst at this point. We used to have a BUG
|
|
* here if folio_trylock(dst) fails, but would like to allow for
|
|
* cases where there might be a race with the previous use of dst.
|
|
* This is much like races on refcount of oldpage: just don't BUG().
|
|
*/
|
|
if (unlikely(!folio_trylock(dst)))
|
|
goto out;
|
|
dst_locked = true;
|
|
|
|
if (unlikely(!is_lru)) {
|
|
__migrate_folio_record(dst, old_page_state, anon_vma);
|
|
return MIGRATEPAGE_UNMAP;
|
|
}
|
|
|
|
/*
|
|
* Corner case handling:
|
|
* 1. When a new swap-cache page is read into, it is added to the LRU
|
|
* and treated as swapcache but it has no rmap yet.
|
|
* Calling try_to_unmap() against a src->mapping==NULL page will
|
|
* trigger a BUG. So handle it here.
|
|
* 2. An orphaned page (see truncate_cleanup_page) might have
|
|
* fs-private metadata. The page can be picked up due to memory
|
|
* offlining. Everywhere else except page reclaim, the page is
|
|
* invisible to the vm, so the page can not be migrated. So try to
|
|
* free the metadata, so the page can be freed.
|
|
*/
|
|
if (!src->mapping) {
|
|
if (folio_test_private(src)) {
|
|
try_to_free_buffers(src);
|
|
goto out;
|
|
}
|
|
} else if (folio_mapped(src)) {
|
|
/* Establish migration ptes */
|
|
VM_BUG_ON_FOLIO(folio_test_anon(src) &&
|
|
!folio_test_ksm(src) && !anon_vma, src);
|
|
try_to_migrate(src, mode == MIGRATE_ASYNC ? TTU_BATCH_FLUSH : 0);
|
|
old_page_state |= PAGE_WAS_MAPPED;
|
|
}
|
|
|
|
if (!folio_mapped(src)) {
|
|
__migrate_folio_record(dst, old_page_state, anon_vma);
|
|
return MIGRATEPAGE_UNMAP;
|
|
}
|
|
|
|
out:
|
|
/*
|
|
* A folio that has not been unmapped will be restored to
|
|
* right list unless we want to retry.
|
|
*/
|
|
if (rc == -EAGAIN)
|
|
ret = NULL;
|
|
|
|
migrate_folio_undo_src(src, old_page_state & PAGE_WAS_MAPPED,
|
|
anon_vma, locked, ret);
|
|
migrate_folio_undo_dst(dst, dst_locked, put_new_folio, private);
|
|
|
|
return rc;
|
|
}
|
|
|
|
/* Migrate the folio to the newly allocated folio in dst. */
|
|
static int migrate_folio_move(free_folio_t put_new_folio, unsigned long private,
|
|
struct folio *src, struct folio *dst,
|
|
enum migrate_mode mode, enum migrate_reason reason,
|
|
struct list_head *ret)
|
|
{
|
|
int rc;
|
|
int old_page_state = 0;
|
|
struct anon_vma *anon_vma = NULL;
|
|
bool is_lru = !__folio_test_movable(src);
|
|
struct list_head *prev;
|
|
|
|
__migrate_folio_extract(dst, &old_page_state, &anon_vma);
|
|
prev = dst->lru.prev;
|
|
list_del(&dst->lru);
|
|
|
|
rc = move_to_new_folio(dst, src, mode);
|
|
if (rc)
|
|
goto out;
|
|
|
|
if (unlikely(!is_lru))
|
|
goto out_unlock_both;
|
|
|
|
/*
|
|
* When successful, push dst to LRU immediately: so that if it
|
|
* turns out to be an mlocked page, remove_migration_ptes() will
|
|
* automatically build up the correct dst->mlock_count for it.
|
|
*
|
|
* We would like to do something similar for the old page, when
|
|
* unsuccessful, and other cases when a page has been temporarily
|
|
* isolated from the unevictable LRU: but this case is the easiest.
|
|
*/
|
|
folio_add_lru(dst);
|
|
if (old_page_state & PAGE_WAS_MLOCKED)
|
|
lru_add_drain();
|
|
|
|
if (old_page_state & PAGE_WAS_MAPPED)
|
|
remove_migration_ptes(src, dst, false);
|
|
|
|
out_unlock_both:
|
|
folio_unlock(dst);
|
|
set_page_owner_migrate_reason(&dst->page, reason);
|
|
/*
|
|
* If migration is successful, decrease refcount of dst,
|
|
* which will not free the page because new page owner increased
|
|
* refcounter.
|
|
*/
|
|
folio_put(dst);
|
|
|
|
/*
|
|
* A folio that has been migrated has all references removed
|
|
* and will be freed.
|
|
*/
|
|
list_del(&src->lru);
|
|
/* Drop an anon_vma reference if we took one */
|
|
if (anon_vma)
|
|
put_anon_vma(anon_vma);
|
|
folio_unlock(src);
|
|
migrate_folio_done(src, reason);
|
|
|
|
return rc;
|
|
out:
|
|
/*
|
|
* A folio that has not been migrated will be restored to
|
|
* right list unless we want to retry.
|
|
*/
|
|
if (rc == -EAGAIN) {
|
|
list_add(&dst->lru, prev);
|
|
__migrate_folio_record(dst, old_page_state, anon_vma);
|
|
return rc;
|
|
}
|
|
|
|
migrate_folio_undo_src(src, old_page_state & PAGE_WAS_MAPPED,
|
|
anon_vma, true, ret);
|
|
migrate_folio_undo_dst(dst, true, put_new_folio, private);
|
|
|
|
return rc;
|
|
}
|
|
|
|
/*
|
|
* Counterpart of unmap_and_move_page() for hugepage migration.
|
|
*
|
|
* This function doesn't wait the completion of hugepage I/O
|
|
* because there is no race between I/O and migration for hugepage.
|
|
* Note that currently hugepage I/O occurs only in direct I/O
|
|
* where no lock is held and PG_writeback is irrelevant,
|
|
* and writeback status of all subpages are counted in the reference
|
|
* count of the head page (i.e. if all subpages of a 2MB hugepage are
|
|
* under direct I/O, the reference of the head page is 512 and a bit more.)
|
|
* This means that when we try to migrate hugepage whose subpages are
|
|
* doing direct I/O, some references remain after try_to_unmap() and
|
|
* hugepage migration fails without data corruption.
|
|
*
|
|
* There is also no race when direct I/O is issued on the page under migration,
|
|
* because then pte is replaced with migration swap entry and direct I/O code
|
|
* will wait in the page fault for migration to complete.
|
|
*/
|
|
static int unmap_and_move_huge_page(new_folio_t get_new_folio,
|
|
free_folio_t put_new_folio, unsigned long private,
|
|
struct folio *src, int force, enum migrate_mode mode,
|
|
int reason, struct list_head *ret)
|
|
{
|
|
struct folio *dst;
|
|
int rc = -EAGAIN;
|
|
int page_was_mapped = 0;
|
|
struct anon_vma *anon_vma = NULL;
|
|
struct address_space *mapping = NULL;
|
|
|
|
if (folio_ref_count(src) == 1) {
|
|
/* page was freed from under us. So we are done. */
|
|
folio_putback_active_hugetlb(src);
|
|
return MIGRATEPAGE_SUCCESS;
|
|
}
|
|
|
|
dst = get_new_folio(src, private);
|
|
if (!dst)
|
|
return -ENOMEM;
|
|
|
|
if (!folio_trylock(src)) {
|
|
if (!force)
|
|
goto out;
|
|
switch (mode) {
|
|
case MIGRATE_SYNC:
|
|
case MIGRATE_SYNC_NO_COPY:
|
|
break;
|
|
default:
|
|
goto out;
|
|
}
|
|
folio_lock(src);
|
|
}
|
|
|
|
/*
|
|
* Check for pages which are in the process of being freed. Without
|
|
* folio_mapping() set, hugetlbfs specific move page routine will not
|
|
* be called and we could leak usage counts for subpools.
|
|
*/
|
|
if (hugetlb_folio_subpool(src) && !folio_mapping(src)) {
|
|
rc = -EBUSY;
|
|
goto out_unlock;
|
|
}
|
|
|
|
if (folio_test_anon(src))
|
|
anon_vma = folio_get_anon_vma(src);
|
|
|
|
if (unlikely(!folio_trylock(dst)))
|
|
goto put_anon;
|
|
|
|
if (folio_mapped(src)) {
|
|
enum ttu_flags ttu = 0;
|
|
|
|
if (!folio_test_anon(src)) {
|
|
/*
|
|
* In shared mappings, try_to_unmap could potentially
|
|
* call huge_pmd_unshare. Because of this, take
|
|
* semaphore in write mode here and set TTU_RMAP_LOCKED
|
|
* to let lower levels know we have taken the lock.
|
|
*/
|
|
mapping = hugetlb_page_mapping_lock_write(&src->page);
|
|
if (unlikely(!mapping))
|
|
goto unlock_put_anon;
|
|
|
|
ttu = TTU_RMAP_LOCKED;
|
|
}
|
|
|
|
try_to_migrate(src, ttu);
|
|
page_was_mapped = 1;
|
|
|
|
if (ttu & TTU_RMAP_LOCKED)
|
|
i_mmap_unlock_write(mapping);
|
|
}
|
|
|
|
if (!folio_mapped(src))
|
|
rc = move_to_new_folio(dst, src, mode);
|
|
|
|
if (page_was_mapped)
|
|
remove_migration_ptes(src,
|
|
rc == MIGRATEPAGE_SUCCESS ? dst : src, false);
|
|
|
|
unlock_put_anon:
|
|
folio_unlock(dst);
|
|
|
|
put_anon:
|
|
if (anon_vma)
|
|
put_anon_vma(anon_vma);
|
|
|
|
if (rc == MIGRATEPAGE_SUCCESS) {
|
|
move_hugetlb_state(src, dst, reason);
|
|
put_new_folio = NULL;
|
|
}
|
|
|
|
out_unlock:
|
|
folio_unlock(src);
|
|
out:
|
|
if (rc == MIGRATEPAGE_SUCCESS)
|
|
folio_putback_active_hugetlb(src);
|
|
else if (rc != -EAGAIN)
|
|
list_move_tail(&src->lru, ret);
|
|
|
|
/*
|
|
* If migration was not successful and there's a freeing callback, use
|
|
* it. Otherwise, put_page() will drop the reference grabbed during
|
|
* isolation.
|
|
*/
|
|
if (put_new_folio)
|
|
put_new_folio(dst, private);
|
|
else
|
|
folio_putback_active_hugetlb(dst);
|
|
|
|
return rc;
|
|
}
|
|
|
|
static inline int try_split_folio(struct folio *folio, struct list_head *split_folios)
|
|
{
|
|
int rc;
|
|
|
|
folio_lock(folio);
|
|
rc = split_folio_to_list(folio, split_folios);
|
|
folio_unlock(folio);
|
|
if (!rc)
|
|
list_move_tail(&folio->lru, split_folios);
|
|
|
|
return rc;
|
|
}
|
|
|
|
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
|
|
#define NR_MAX_BATCHED_MIGRATION HPAGE_PMD_NR
|
|
#else
|
|
#define NR_MAX_BATCHED_MIGRATION 512
|
|
#endif
|
|
#define NR_MAX_MIGRATE_PAGES_RETRY 10
|
|
#define NR_MAX_MIGRATE_ASYNC_RETRY 3
|
|
#define NR_MAX_MIGRATE_SYNC_RETRY \
|
|
(NR_MAX_MIGRATE_PAGES_RETRY - NR_MAX_MIGRATE_ASYNC_RETRY)
|
|
|
|
struct migrate_pages_stats {
|
|
int nr_succeeded; /* Normal and large folios migrated successfully, in
|
|
units of base pages */
|
|
int nr_failed_pages; /* Normal and large folios failed to be migrated, in
|
|
units of base pages. Untried folios aren't counted */
|
|
int nr_thp_succeeded; /* THP migrated successfully */
|
|
int nr_thp_failed; /* THP failed to be migrated */
|
|
int nr_thp_split; /* THP split before migrating */
|
|
int nr_split; /* Large folio (include THP) split before migrating */
|
|
};
|
|
|
|
/*
|
|
* Returns the number of hugetlb folios that were not migrated, or an error code
|
|
* after NR_MAX_MIGRATE_PAGES_RETRY attempts or if no hugetlb folios are movable
|
|
* any more because the list has become empty or no retryable hugetlb folios
|
|
* exist any more. It is caller's responsibility to call putback_movable_pages()
|
|
* only if ret != 0.
|
|
*/
|
|
static int migrate_hugetlbs(struct list_head *from, new_folio_t get_new_folio,
|
|
free_folio_t put_new_folio, unsigned long private,
|
|
enum migrate_mode mode, int reason,
|
|
struct migrate_pages_stats *stats,
|
|
struct list_head *ret_folios)
|
|
{
|
|
int retry = 1;
|
|
int nr_failed = 0;
|
|
int nr_retry_pages = 0;
|
|
int pass = 0;
|
|
struct folio *folio, *folio2;
|
|
int rc, nr_pages;
|
|
|
|
for (pass = 0; pass < NR_MAX_MIGRATE_PAGES_RETRY && retry; pass++) {
|
|
retry = 0;
|
|
nr_retry_pages = 0;
|
|
|
|
list_for_each_entry_safe(folio, folio2, from, lru) {
|
|
if (!folio_test_hugetlb(folio))
|
|
continue;
|
|
|
|
nr_pages = folio_nr_pages(folio);
|
|
|
|
cond_resched();
|
|
|
|
/*
|
|
* Migratability of hugepages depends on architectures and
|
|
* their size. This check is necessary because some callers
|
|
* of hugepage migration like soft offline and memory
|
|
* hotremove don't walk through page tables or check whether
|
|
* the hugepage is pmd-based or not before kicking migration.
|
|
*/
|
|
if (!hugepage_migration_supported(folio_hstate(folio))) {
|
|
nr_failed++;
|
|
stats->nr_failed_pages += nr_pages;
|
|
list_move_tail(&folio->lru, ret_folios);
|
|
continue;
|
|
}
|
|
|
|
rc = unmap_and_move_huge_page(get_new_folio,
|
|
put_new_folio, private,
|
|
folio, pass > 2, mode,
|
|
reason, ret_folios);
|
|
/*
|
|
* The rules are:
|
|
* Success: hugetlb folio will be put back
|
|
* -EAGAIN: stay on the from list
|
|
* -ENOMEM: stay on the from list
|
|
* Other errno: put on ret_folios list
|
|
*/
|
|
switch(rc) {
|
|
case -ENOMEM:
|
|
/*
|
|
* When memory is low, don't bother to try to migrate
|
|
* other folios, just exit.
|
|
*/
|
|
stats->nr_failed_pages += nr_pages + nr_retry_pages;
|
|
return -ENOMEM;
|
|
case -EAGAIN:
|
|
retry++;
|
|
nr_retry_pages += nr_pages;
|
|
break;
|
|
case MIGRATEPAGE_SUCCESS:
|
|
stats->nr_succeeded += nr_pages;
|
|
break;
|
|
default:
|
|
/*
|
|
* Permanent failure (-EBUSY, etc.):
|
|
* unlike -EAGAIN case, the failed folio is
|
|
* removed from migration folio list and not
|
|
* retried in the next outer loop.
|
|
*/
|
|
nr_failed++;
|
|
stats->nr_failed_pages += nr_pages;
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
/*
|
|
* nr_failed is number of hugetlb folios failed to be migrated. After
|
|
* NR_MAX_MIGRATE_PAGES_RETRY attempts, give up and count retried hugetlb
|
|
* folios as failed.
|
|
*/
|
|
nr_failed += retry;
|
|
stats->nr_failed_pages += nr_retry_pages;
|
|
|
|
return nr_failed;
|
|
}
|
|
|
|
/*
|
|
* migrate_pages_batch() first unmaps folios in the from list as many as
|
|
* possible, then move the unmapped folios.
|
|
*
|
|
* We only batch migration if mode == MIGRATE_ASYNC to avoid to wait a
|
|
* lock or bit when we have locked more than one folio. Which may cause
|
|
* deadlock (e.g., for loop device). So, if mode != MIGRATE_ASYNC, the
|
|
* length of the from list must be <= 1.
|
|
*/
|
|
static int migrate_pages_batch(struct list_head *from,
|
|
new_folio_t get_new_folio, free_folio_t put_new_folio,
|
|
unsigned long private, enum migrate_mode mode, int reason,
|
|
struct list_head *ret_folios, struct list_head *split_folios,
|
|
struct migrate_pages_stats *stats, int nr_pass)
|
|
{
|
|
int retry = 1;
|
|
int thp_retry = 1;
|
|
int nr_failed = 0;
|
|
int nr_retry_pages = 0;
|
|
int pass = 0;
|
|
bool is_thp = false;
|
|
bool is_large = false;
|
|
struct folio *folio, *folio2, *dst = NULL, *dst2;
|
|
int rc, rc_saved = 0, nr_pages;
|
|
LIST_HEAD(unmap_folios);
|
|
LIST_HEAD(dst_folios);
|
|
bool nosplit = (reason == MR_NUMA_MISPLACED);
|
|
|
|
VM_WARN_ON_ONCE(mode != MIGRATE_ASYNC &&
|
|
!list_empty(from) && !list_is_singular(from));
|
|
|
|
for (pass = 0; pass < nr_pass && retry; pass++) {
|
|
retry = 0;
|
|
thp_retry = 0;
|
|
nr_retry_pages = 0;
|
|
|
|
list_for_each_entry_safe(folio, folio2, from, lru) {
|
|
is_large = folio_test_large(folio);
|
|
is_thp = is_large && folio_test_pmd_mappable(folio);
|
|
nr_pages = folio_nr_pages(folio);
|
|
|
|
cond_resched();
|
|
|
|
/*
|
|
* Large folio migration might be unsupported or
|
|
* the allocation might be failed so we should retry
|
|
* on the same folio with the large folio split
|
|
* to normal folios.
|
|
*
|
|
* Split folios are put in split_folios, and
|
|
* we will migrate them after the rest of the
|
|
* list is processed.
|
|
*/
|
|
if (!thp_migration_supported() && is_thp) {
|
|
nr_failed++;
|
|
stats->nr_thp_failed++;
|
|
if (!try_split_folio(folio, split_folios)) {
|
|
stats->nr_thp_split++;
|
|
stats->nr_split++;
|
|
continue;
|
|
}
|
|
stats->nr_failed_pages += nr_pages;
|
|
list_move_tail(&folio->lru, ret_folios);
|
|
continue;
|
|
}
|
|
|
|
rc = migrate_folio_unmap(get_new_folio, put_new_folio,
|
|
private, folio, &dst, mode, reason,
|
|
ret_folios);
|
|
/*
|
|
* The rules are:
|
|
* Success: folio will be freed
|
|
* Unmap: folio will be put on unmap_folios list,
|
|
* dst folio put on dst_folios list
|
|
* -EAGAIN: stay on the from list
|
|
* -ENOMEM: stay on the from list
|
|
* Other errno: put on ret_folios list
|
|
*/
|
|
switch(rc) {
|
|
case -ENOMEM:
|
|
/*
|
|
* When memory is low, don't bother to try to migrate
|
|
* other folios, move unmapped folios, then exit.
|
|
*/
|
|
nr_failed++;
|
|
stats->nr_thp_failed += is_thp;
|
|
/* Large folio NUMA faulting doesn't split to retry. */
|
|
if (is_large && !nosplit) {
|
|
int ret = try_split_folio(folio, split_folios);
|
|
|
|
if (!ret) {
|
|
stats->nr_thp_split += is_thp;
|
|
stats->nr_split++;
|
|
break;
|
|
} else if (reason == MR_LONGTERM_PIN &&
|
|
ret == -EAGAIN) {
|
|
/*
|
|
* Try again to split large folio to
|
|
* mitigate the failure of longterm pinning.
|
|
*/
|
|
retry++;
|
|
thp_retry += is_thp;
|
|
nr_retry_pages += nr_pages;
|
|
/* Undo duplicated failure counting. */
|
|
nr_failed--;
|
|
stats->nr_thp_failed -= is_thp;
|
|
break;
|
|
}
|
|
}
|
|
|
|
stats->nr_failed_pages += nr_pages + nr_retry_pages;
|
|
/* nr_failed isn't updated for not used */
|
|
stats->nr_thp_failed += thp_retry;
|
|
rc_saved = rc;
|
|
if (list_empty(&unmap_folios))
|
|
goto out;
|
|
else
|
|
goto move;
|
|
case -EAGAIN:
|
|
retry++;
|
|
thp_retry += is_thp;
|
|
nr_retry_pages += nr_pages;
|
|
break;
|
|
case MIGRATEPAGE_SUCCESS:
|
|
stats->nr_succeeded += nr_pages;
|
|
stats->nr_thp_succeeded += is_thp;
|
|
break;
|
|
case MIGRATEPAGE_UNMAP:
|
|
list_move_tail(&folio->lru, &unmap_folios);
|
|
list_add_tail(&dst->lru, &dst_folios);
|
|
break;
|
|
default:
|
|
/*
|
|
* Permanent failure (-EBUSY, etc.):
|
|
* unlike -EAGAIN case, the failed folio is
|
|
* removed from migration folio list and not
|
|
* retried in the next outer loop.
|
|
*/
|
|
nr_failed++;
|
|
stats->nr_thp_failed += is_thp;
|
|
stats->nr_failed_pages += nr_pages;
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
nr_failed += retry;
|
|
stats->nr_thp_failed += thp_retry;
|
|
stats->nr_failed_pages += nr_retry_pages;
|
|
move:
|
|
/* Flush TLBs for all unmapped folios */
|
|
try_to_unmap_flush();
|
|
|
|
retry = 1;
|
|
for (pass = 0; pass < nr_pass && retry; pass++) {
|
|
retry = 0;
|
|
thp_retry = 0;
|
|
nr_retry_pages = 0;
|
|
|
|
dst = list_first_entry(&dst_folios, struct folio, lru);
|
|
dst2 = list_next_entry(dst, lru);
|
|
list_for_each_entry_safe(folio, folio2, &unmap_folios, lru) {
|
|
is_thp = folio_test_large(folio) && folio_test_pmd_mappable(folio);
|
|
nr_pages = folio_nr_pages(folio);
|
|
|
|
cond_resched();
|
|
|
|
rc = migrate_folio_move(put_new_folio, private,
|
|
folio, dst, mode,
|
|
reason, ret_folios);
|
|
/*
|
|
* The rules are:
|
|
* Success: folio will be freed
|
|
* -EAGAIN: stay on the unmap_folios list
|
|
* Other errno: put on ret_folios list
|
|
*/
|
|
switch(rc) {
|
|
case -EAGAIN:
|
|
retry++;
|
|
thp_retry += is_thp;
|
|
nr_retry_pages += nr_pages;
|
|
break;
|
|
case MIGRATEPAGE_SUCCESS:
|
|
stats->nr_succeeded += nr_pages;
|
|
stats->nr_thp_succeeded += is_thp;
|
|
break;
|
|
default:
|
|
nr_failed++;
|
|
stats->nr_thp_failed += is_thp;
|
|
stats->nr_failed_pages += nr_pages;
|
|
break;
|
|
}
|
|
dst = dst2;
|
|
dst2 = list_next_entry(dst, lru);
|
|
}
|
|
}
|
|
nr_failed += retry;
|
|
stats->nr_thp_failed += thp_retry;
|
|
stats->nr_failed_pages += nr_retry_pages;
|
|
|
|
rc = rc_saved ? : nr_failed;
|
|
out:
|
|
/* Cleanup remaining folios */
|
|
dst = list_first_entry(&dst_folios, struct folio, lru);
|
|
dst2 = list_next_entry(dst, lru);
|
|
list_for_each_entry_safe(folio, folio2, &unmap_folios, lru) {
|
|
int old_page_state = 0;
|
|
struct anon_vma *anon_vma = NULL;
|
|
|
|
__migrate_folio_extract(dst, &old_page_state, &anon_vma);
|
|
migrate_folio_undo_src(folio, old_page_state & PAGE_WAS_MAPPED,
|
|
anon_vma, true, ret_folios);
|
|
list_del(&dst->lru);
|
|
migrate_folio_undo_dst(dst, true, put_new_folio, private);
|
|
dst = dst2;
|
|
dst2 = list_next_entry(dst, lru);
|
|
}
|
|
|
|
return rc;
|
|
}
|
|
|
|
static int migrate_pages_sync(struct list_head *from, new_folio_t get_new_folio,
|
|
free_folio_t put_new_folio, unsigned long private,
|
|
enum migrate_mode mode, int reason,
|
|
struct list_head *ret_folios, struct list_head *split_folios,
|
|
struct migrate_pages_stats *stats)
|
|
{
|
|
int rc, nr_failed = 0;
|
|
LIST_HEAD(folios);
|
|
struct migrate_pages_stats astats;
|
|
|
|
memset(&astats, 0, sizeof(astats));
|
|
/* Try to migrate in batch with MIGRATE_ASYNC mode firstly */
|
|
rc = migrate_pages_batch(from, get_new_folio, put_new_folio, private, MIGRATE_ASYNC,
|
|
reason, &folios, split_folios, &astats,
|
|
NR_MAX_MIGRATE_ASYNC_RETRY);
|
|
stats->nr_succeeded += astats.nr_succeeded;
|
|
stats->nr_thp_succeeded += astats.nr_thp_succeeded;
|
|
stats->nr_thp_split += astats.nr_thp_split;
|
|
stats->nr_split += astats.nr_split;
|
|
if (rc < 0) {
|
|
stats->nr_failed_pages += astats.nr_failed_pages;
|
|
stats->nr_thp_failed += astats.nr_thp_failed;
|
|
list_splice_tail(&folios, ret_folios);
|
|
return rc;
|
|
}
|
|
stats->nr_thp_failed += astats.nr_thp_split;
|
|
/*
|
|
* Do not count rc, as pages will be retried below.
|
|
* Count nr_split only, since it includes nr_thp_split.
|
|
*/
|
|
nr_failed += astats.nr_split;
|
|
/*
|
|
* Fall back to migrate all failed folios one by one synchronously. All
|
|
* failed folios except split THPs will be retried, so their failure
|
|
* isn't counted
|
|
*/
|
|
list_splice_tail_init(&folios, from);
|
|
while (!list_empty(from)) {
|
|
list_move(from->next, &folios);
|
|
rc = migrate_pages_batch(&folios, get_new_folio, put_new_folio,
|
|
private, mode, reason, ret_folios,
|
|
split_folios, stats, NR_MAX_MIGRATE_SYNC_RETRY);
|
|
list_splice_tail_init(&folios, ret_folios);
|
|
if (rc < 0)
|
|
return rc;
|
|
nr_failed += rc;
|
|
}
|
|
|
|
return nr_failed;
|
|
}
|
|
|
|
/*
|
|
* migrate_pages - migrate the folios specified in a list, to the free folios
|
|
* supplied as the target for the page migration
|
|
*
|
|
* @from: The list of folios to be migrated.
|
|
* @get_new_folio: The function used to allocate free folios to be used
|
|
* as the target of the folio migration.
|
|
* @put_new_folio: The function used to free target folios if migration
|
|
* fails, or NULL if no special handling is necessary.
|
|
* @private: Private data to be passed on to get_new_folio()
|
|
* @mode: The migration mode that specifies the constraints for
|
|
* folio migration, if any.
|
|
* @reason: The reason for folio migration.
|
|
* @ret_succeeded: Set to the number of folios migrated successfully if
|
|
* the caller passes a non-NULL pointer.
|
|
*
|
|
* The function returns after NR_MAX_MIGRATE_PAGES_RETRY attempts or if no folios
|
|
* are movable any more because the list has become empty or no retryable folios
|
|
* exist any more. It is caller's responsibility to call putback_movable_pages()
|
|
* only if ret != 0.
|
|
*
|
|
* Returns the number of {normal folio, large folio, hugetlb} that were not
|
|
* migrated, or an error code. The number of large folio splits will be
|
|
* considered as the number of non-migrated large folio, no matter how many
|
|
* split folios of the large folio are migrated successfully.
|
|
*/
|
|
int migrate_pages(struct list_head *from, new_folio_t get_new_folio,
|
|
free_folio_t put_new_folio, unsigned long private,
|
|
enum migrate_mode mode, int reason, unsigned int *ret_succeeded)
|
|
{
|
|
int rc, rc_gather;
|
|
int nr_pages;
|
|
struct folio *folio, *folio2;
|
|
LIST_HEAD(folios);
|
|
LIST_HEAD(ret_folios);
|
|
LIST_HEAD(split_folios);
|
|
struct migrate_pages_stats stats;
|
|
|
|
trace_mm_migrate_pages_start(mode, reason);
|
|
|
|
memset(&stats, 0, sizeof(stats));
|
|
|
|
rc_gather = migrate_hugetlbs(from, get_new_folio, put_new_folio, private,
|
|
mode, reason, &stats, &ret_folios);
|
|
if (rc_gather < 0)
|
|
goto out;
|
|
|
|
again:
|
|
nr_pages = 0;
|
|
list_for_each_entry_safe(folio, folio2, from, lru) {
|
|
/* Retried hugetlb folios will be kept in list */
|
|
if (folio_test_hugetlb(folio)) {
|
|
list_move_tail(&folio->lru, &ret_folios);
|
|
continue;
|
|
}
|
|
|
|
nr_pages += folio_nr_pages(folio);
|
|
if (nr_pages >= NR_MAX_BATCHED_MIGRATION)
|
|
break;
|
|
}
|
|
if (nr_pages >= NR_MAX_BATCHED_MIGRATION)
|
|
list_cut_before(&folios, from, &folio2->lru);
|
|
else
|
|
list_splice_init(from, &folios);
|
|
if (mode == MIGRATE_ASYNC)
|
|
rc = migrate_pages_batch(&folios, get_new_folio, put_new_folio,
|
|
private, mode, reason, &ret_folios,
|
|
&split_folios, &stats,
|
|
NR_MAX_MIGRATE_PAGES_RETRY);
|
|
else
|
|
rc = migrate_pages_sync(&folios, get_new_folio, put_new_folio,
|
|
private, mode, reason, &ret_folios,
|
|
&split_folios, &stats);
|
|
list_splice_tail_init(&folios, &ret_folios);
|
|
if (rc < 0) {
|
|
rc_gather = rc;
|
|
list_splice_tail(&split_folios, &ret_folios);
|
|
goto out;
|
|
}
|
|
if (!list_empty(&split_folios)) {
|
|
/*
|
|
* Failure isn't counted since all split folios of a large folio
|
|
* is counted as 1 failure already. And, we only try to migrate
|
|
* with minimal effort, force MIGRATE_ASYNC mode and retry once.
|
|
*/
|
|
migrate_pages_batch(&split_folios, get_new_folio,
|
|
put_new_folio, private, MIGRATE_ASYNC, reason,
|
|
&ret_folios, NULL, &stats, 1);
|
|
list_splice_tail_init(&split_folios, &ret_folios);
|
|
}
|
|
rc_gather += rc;
|
|
if (!list_empty(from))
|
|
goto again;
|
|
out:
|
|
/*
|
|
* Put the permanent failure folio back to migration list, they
|
|
* will be put back to the right list by the caller.
|
|
*/
|
|
list_splice(&ret_folios, from);
|
|
|
|
/*
|
|
* Return 0 in case all split folios of fail-to-migrate large folios
|
|
* are migrated successfully.
|
|
*/
|
|
if (list_empty(from))
|
|
rc_gather = 0;
|
|
|
|
count_vm_events(PGMIGRATE_SUCCESS, stats.nr_succeeded);
|
|
count_vm_events(PGMIGRATE_FAIL, stats.nr_failed_pages);
|
|
count_vm_events(THP_MIGRATION_SUCCESS, stats.nr_thp_succeeded);
|
|
count_vm_events(THP_MIGRATION_FAIL, stats.nr_thp_failed);
|
|
count_vm_events(THP_MIGRATION_SPLIT, stats.nr_thp_split);
|
|
trace_mm_migrate_pages(stats.nr_succeeded, stats.nr_failed_pages,
|
|
stats.nr_thp_succeeded, stats.nr_thp_failed,
|
|
stats.nr_thp_split, stats.nr_split, mode,
|
|
reason);
|
|
|
|
if (ret_succeeded)
|
|
*ret_succeeded = stats.nr_succeeded;
|
|
|
|
return rc_gather;
|
|
}
|
|
|
|
struct folio *alloc_migration_target(struct folio *src, unsigned long private)
|
|
{
|
|
struct migration_target_control *mtc;
|
|
gfp_t gfp_mask;
|
|
unsigned int order = 0;
|
|
int nid;
|
|
int zidx;
|
|
|
|
mtc = (struct migration_target_control *)private;
|
|
gfp_mask = mtc->gfp_mask;
|
|
nid = mtc->nid;
|
|
if (nid == NUMA_NO_NODE)
|
|
nid = folio_nid(src);
|
|
|
|
if (folio_test_hugetlb(src)) {
|
|
struct hstate *h = folio_hstate(src);
|
|
|
|
gfp_mask = htlb_modify_alloc_mask(h, gfp_mask);
|
|
return alloc_hugetlb_folio_nodemask(h, nid,
|
|
mtc->nmask, gfp_mask);
|
|
}
|
|
|
|
if (folio_test_large(src)) {
|
|
/*
|
|
* clear __GFP_RECLAIM to make the migration callback
|
|
* consistent with regular THP allocations.
|
|
*/
|
|
gfp_mask &= ~__GFP_RECLAIM;
|
|
gfp_mask |= GFP_TRANSHUGE;
|
|
order = folio_order(src);
|
|
}
|
|
zidx = zone_idx(folio_zone(src));
|
|
if (is_highmem_idx(zidx) || zidx == ZONE_MOVABLE)
|
|
gfp_mask |= __GFP_HIGHMEM;
|
|
|
|
return __folio_alloc(gfp_mask, order, nid, mtc->nmask);
|
|
}
|
|
|
|
#ifdef CONFIG_NUMA
|
|
|
|
static int store_status(int __user *status, int start, int value, int nr)
|
|
{
|
|
while (nr-- > 0) {
|
|
if (put_user(value, status + start))
|
|
return -EFAULT;
|
|
start++;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int do_move_pages_to_node(struct list_head *pagelist, int node)
|
|
{
|
|
int err;
|
|
struct migration_target_control mtc = {
|
|
.nid = node,
|
|
.gfp_mask = GFP_HIGHUSER_MOVABLE | __GFP_THISNODE,
|
|
};
|
|
|
|
err = migrate_pages(pagelist, alloc_migration_target, NULL,
|
|
(unsigned long)&mtc, MIGRATE_SYNC, MR_SYSCALL, NULL);
|
|
if (err)
|
|
putback_movable_pages(pagelist);
|
|
return err;
|
|
}
|
|
|
|
/*
|
|
* Resolves the given address to a struct page, isolates it from the LRU and
|
|
* puts it to the given pagelist.
|
|
* Returns:
|
|
* errno - if the page cannot be found/isolated
|
|
* 0 - when it doesn't have to be migrated because it is already on the
|
|
* target node
|
|
* 1 - when it has been queued
|
|
*/
|
|
static int add_page_for_migration(struct mm_struct *mm, const void __user *p,
|
|
int node, struct list_head *pagelist, bool migrate_all)
|
|
{
|
|
struct vm_area_struct *vma;
|
|
unsigned long addr;
|
|
struct page *page;
|
|
struct folio *folio;
|
|
int err;
|
|
|
|
mmap_read_lock(mm);
|
|
addr = (unsigned long)untagged_addr_remote(mm, p);
|
|
|
|
err = -EFAULT;
|
|
vma = vma_lookup(mm, addr);
|
|
if (!vma || !vma_migratable(vma))
|
|
goto out;
|
|
|
|
/* FOLL_DUMP to ignore special (like zero) pages */
|
|
page = follow_page(vma, addr, FOLL_GET | FOLL_DUMP);
|
|
|
|
err = PTR_ERR(page);
|
|
if (IS_ERR(page))
|
|
goto out;
|
|
|
|
err = -ENOENT;
|
|
if (!page)
|
|
goto out;
|
|
|
|
folio = page_folio(page);
|
|
if (folio_is_zone_device(folio))
|
|
goto out_putfolio;
|
|
|
|
err = 0;
|
|
if (folio_nid(folio) == node)
|
|
goto out_putfolio;
|
|
|
|
err = -EACCES;
|
|
if (page_mapcount(page) > 1 && !migrate_all)
|
|
goto out_putfolio;
|
|
|
|
err = -EBUSY;
|
|
if (folio_test_hugetlb(folio)) {
|
|
if (isolate_hugetlb(folio, pagelist))
|
|
err = 1;
|
|
} else {
|
|
if (!folio_isolate_lru(folio))
|
|
goto out_putfolio;
|
|
|
|
err = 1;
|
|
list_add_tail(&folio->lru, pagelist);
|
|
node_stat_mod_folio(folio,
|
|
NR_ISOLATED_ANON + folio_is_file_lru(folio),
|
|
folio_nr_pages(folio));
|
|
}
|
|
out_putfolio:
|
|
/*
|
|
* Either remove the duplicate refcount from folio_isolate_lru()
|
|
* or drop the folio ref if it was not isolated.
|
|
*/
|
|
folio_put(folio);
|
|
out:
|
|
mmap_read_unlock(mm);
|
|
return err;
|
|
}
|
|
|
|
static int move_pages_and_store_status(int node,
|
|
struct list_head *pagelist, int __user *status,
|
|
int start, int i, unsigned long nr_pages)
|
|
{
|
|
int err;
|
|
|
|
if (list_empty(pagelist))
|
|
return 0;
|
|
|
|
err = do_move_pages_to_node(pagelist, node);
|
|
if (err) {
|
|
/*
|
|
* Positive err means the number of failed
|
|
* pages to migrate. Since we are going to
|
|
* abort and return the number of non-migrated
|
|
* pages, so need to include the rest of the
|
|
* nr_pages that have not been attempted as
|
|
* well.
|
|
*/
|
|
if (err > 0)
|
|
err += nr_pages - i;
|
|
return err;
|
|
}
|
|
return store_status(status, start, node, i - start);
|
|
}
|
|
|
|
/*
|
|
* Migrate an array of page address onto an array of nodes and fill
|
|
* the corresponding array of status.
|
|
*/
|
|
static int do_pages_move(struct mm_struct *mm, nodemask_t task_nodes,
|
|
unsigned long nr_pages,
|
|
const void __user * __user *pages,
|
|
const int __user *nodes,
|
|
int __user *status, int flags)
|
|
{
|
|
compat_uptr_t __user *compat_pages = (void __user *)pages;
|
|
int current_node = NUMA_NO_NODE;
|
|
LIST_HEAD(pagelist);
|
|
int start, i;
|
|
int err = 0, err1;
|
|
|
|
lru_cache_disable();
|
|
|
|
for (i = start = 0; i < nr_pages; i++) {
|
|
const void __user *p;
|
|
int node;
|
|
|
|
err = -EFAULT;
|
|
if (in_compat_syscall()) {
|
|
compat_uptr_t cp;
|
|
|
|
if (get_user(cp, compat_pages + i))
|
|
goto out_flush;
|
|
|
|
p = compat_ptr(cp);
|
|
} else {
|
|
if (get_user(p, pages + i))
|
|
goto out_flush;
|
|
}
|
|
if (get_user(node, nodes + i))
|
|
goto out_flush;
|
|
|
|
err = -ENODEV;
|
|
if (node < 0 || node >= MAX_NUMNODES)
|
|
goto out_flush;
|
|
if (!node_state(node, N_MEMORY))
|
|
goto out_flush;
|
|
|
|
err = -EACCES;
|
|
if (!node_isset(node, task_nodes))
|
|
goto out_flush;
|
|
|
|
if (current_node == NUMA_NO_NODE) {
|
|
current_node = node;
|
|
start = i;
|
|
} else if (node != current_node) {
|
|
err = move_pages_and_store_status(current_node,
|
|
&pagelist, status, start, i, nr_pages);
|
|
if (err)
|
|
goto out;
|
|
start = i;
|
|
current_node = node;
|
|
}
|
|
|
|
/*
|
|
* Errors in the page lookup or isolation are not fatal and we simply
|
|
* report them via status
|
|
*/
|
|
err = add_page_for_migration(mm, p, current_node, &pagelist,
|
|
flags & MPOL_MF_MOVE_ALL);
|
|
|
|
if (err > 0) {
|
|
/* The page is successfully queued for migration */
|
|
continue;
|
|
}
|
|
|
|
/*
|
|
* The move_pages() man page does not have an -EEXIST choice, so
|
|
* use -EFAULT instead.
|
|
*/
|
|
if (err == -EEXIST)
|
|
err = -EFAULT;
|
|
|
|
/*
|
|
* If the page is already on the target node (!err), store the
|
|
* node, otherwise, store the err.
|
|
*/
|
|
err = store_status(status, i, err ? : current_node, 1);
|
|
if (err)
|
|
goto out_flush;
|
|
|
|
err = move_pages_and_store_status(current_node, &pagelist,
|
|
status, start, i, nr_pages);
|
|
if (err) {
|
|
/* We have accounted for page i */
|
|
if (err > 0)
|
|
err--;
|
|
goto out;
|
|
}
|
|
current_node = NUMA_NO_NODE;
|
|
}
|
|
out_flush:
|
|
/* Make sure we do not overwrite the existing error */
|
|
err1 = move_pages_and_store_status(current_node, &pagelist,
|
|
status, start, i, nr_pages);
|
|
if (err >= 0)
|
|
err = err1;
|
|
out:
|
|
lru_cache_enable();
|
|
return err;
|
|
}
|
|
|
|
/*
|
|
* Determine the nodes of an array of pages and store it in an array of status.
|
|
*/
|
|
static void do_pages_stat_array(struct mm_struct *mm, unsigned long nr_pages,
|
|
const void __user **pages, int *status)
|
|
{
|
|
unsigned long i;
|
|
|
|
mmap_read_lock(mm);
|
|
|
|
for (i = 0; i < nr_pages; i++) {
|
|
unsigned long addr = (unsigned long)(*pages);
|
|
struct vm_area_struct *vma;
|
|
struct page *page;
|
|
int err = -EFAULT;
|
|
|
|
vma = vma_lookup(mm, addr);
|
|
if (!vma)
|
|
goto set_status;
|
|
|
|
/* FOLL_DUMP to ignore special (like zero) pages */
|
|
page = follow_page(vma, addr, FOLL_GET | FOLL_DUMP);
|
|
|
|
err = PTR_ERR(page);
|
|
if (IS_ERR(page))
|
|
goto set_status;
|
|
|
|
err = -ENOENT;
|
|
if (!page)
|
|
goto set_status;
|
|
|
|
if (!is_zone_device_page(page))
|
|
err = page_to_nid(page);
|
|
|
|
put_page(page);
|
|
set_status:
|
|
*status = err;
|
|
|
|
pages++;
|
|
status++;
|
|
}
|
|
|
|
mmap_read_unlock(mm);
|
|
}
|
|
|
|
static int get_compat_pages_array(const void __user *chunk_pages[],
|
|
const void __user * __user *pages,
|
|
unsigned long chunk_nr)
|
|
{
|
|
compat_uptr_t __user *pages32 = (compat_uptr_t __user *)pages;
|
|
compat_uptr_t p;
|
|
int i;
|
|
|
|
for (i = 0; i < chunk_nr; i++) {
|
|
if (get_user(p, pages32 + i))
|
|
return -EFAULT;
|
|
chunk_pages[i] = compat_ptr(p);
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Determine the nodes of a user array of pages and store it in
|
|
* a user array of status.
|
|
*/
|
|
static int do_pages_stat(struct mm_struct *mm, unsigned long nr_pages,
|
|
const void __user * __user *pages,
|
|
int __user *status)
|
|
{
|
|
#define DO_PAGES_STAT_CHUNK_NR 16UL
|
|
const void __user *chunk_pages[DO_PAGES_STAT_CHUNK_NR];
|
|
int chunk_status[DO_PAGES_STAT_CHUNK_NR];
|
|
|
|
while (nr_pages) {
|
|
unsigned long chunk_nr = min(nr_pages, DO_PAGES_STAT_CHUNK_NR);
|
|
|
|
if (in_compat_syscall()) {
|
|
if (get_compat_pages_array(chunk_pages, pages,
|
|
chunk_nr))
|
|
break;
|
|
} else {
|
|
if (copy_from_user(chunk_pages, pages,
|
|
chunk_nr * sizeof(*chunk_pages)))
|
|
break;
|
|
}
|
|
|
|
do_pages_stat_array(mm, chunk_nr, chunk_pages, chunk_status);
|
|
|
|
if (copy_to_user(status, chunk_status, chunk_nr * sizeof(*status)))
|
|
break;
|
|
|
|
pages += chunk_nr;
|
|
status += chunk_nr;
|
|
nr_pages -= chunk_nr;
|
|
}
|
|
return nr_pages ? -EFAULT : 0;
|
|
}
|
|
|
|
static struct mm_struct *find_mm_struct(pid_t pid, nodemask_t *mem_nodes)
|
|
{
|
|
struct task_struct *task;
|
|
struct mm_struct *mm;
|
|
|
|
/*
|
|
* There is no need to check if current process has the right to modify
|
|
* the specified process when they are same.
|
|
*/
|
|
if (!pid) {
|
|
mmget(current->mm);
|
|
*mem_nodes = cpuset_mems_allowed(current);
|
|
return current->mm;
|
|
}
|
|
|
|
/* Find the mm_struct */
|
|
rcu_read_lock();
|
|
task = find_task_by_vpid(pid);
|
|
if (!task) {
|
|
rcu_read_unlock();
|
|
return ERR_PTR(-ESRCH);
|
|
}
|
|
get_task_struct(task);
|
|
|
|
/*
|
|
* Check if this process has the right to modify the specified
|
|
* process. Use the regular "ptrace_may_access()" checks.
|
|
*/
|
|
if (!ptrace_may_access(task, PTRACE_MODE_READ_REALCREDS)) {
|
|
rcu_read_unlock();
|
|
mm = ERR_PTR(-EPERM);
|
|
goto out;
|
|
}
|
|
rcu_read_unlock();
|
|
|
|
mm = ERR_PTR(security_task_movememory(task));
|
|
if (IS_ERR(mm))
|
|
goto out;
|
|
*mem_nodes = cpuset_mems_allowed(task);
|
|
mm = get_task_mm(task);
|
|
out:
|
|
put_task_struct(task);
|
|
if (!mm)
|
|
mm = ERR_PTR(-EINVAL);
|
|
return mm;
|
|
}
|
|
|
|
/*
|
|
* Move a list of pages in the address space of the currently executing
|
|
* process.
|
|
*/
|
|
static int kernel_move_pages(pid_t pid, unsigned long nr_pages,
|
|
const void __user * __user *pages,
|
|
const int __user *nodes,
|
|
int __user *status, int flags)
|
|
{
|
|
struct mm_struct *mm;
|
|
int err;
|
|
nodemask_t task_nodes;
|
|
|
|
/* Check flags */
|
|
if (flags & ~(MPOL_MF_MOVE|MPOL_MF_MOVE_ALL))
|
|
return -EINVAL;
|
|
|
|
if ((flags & MPOL_MF_MOVE_ALL) && !capable(CAP_SYS_NICE))
|
|
return -EPERM;
|
|
|
|
mm = find_mm_struct(pid, &task_nodes);
|
|
if (IS_ERR(mm))
|
|
return PTR_ERR(mm);
|
|
|
|
if (nodes)
|
|
err = do_pages_move(mm, task_nodes, nr_pages, pages,
|
|
nodes, status, flags);
|
|
else
|
|
err = do_pages_stat(mm, nr_pages, pages, status);
|
|
|
|
mmput(mm);
|
|
return err;
|
|
}
|
|
|
|
SYSCALL_DEFINE6(move_pages, pid_t, pid, unsigned long, nr_pages,
|
|
const void __user * __user *, pages,
|
|
const int __user *, nodes,
|
|
int __user *, status, int, flags)
|
|
{
|
|
return kernel_move_pages(pid, nr_pages, pages, nodes, status, flags);
|
|
}
|
|
|
|
#ifdef CONFIG_NUMA_BALANCING
|
|
/*
|
|
* Returns true if this is a safe migration target node for misplaced NUMA
|
|
* pages. Currently it only checks the watermarks which is crude.
|
|
*/
|
|
static bool migrate_balanced_pgdat(struct pglist_data *pgdat,
|
|
unsigned long nr_migrate_pages)
|
|
{
|
|
int z;
|
|
|
|
for (z = pgdat->nr_zones - 1; z >= 0; z--) {
|
|
struct zone *zone = pgdat->node_zones + z;
|
|
|
|
if (!managed_zone(zone))
|
|
continue;
|
|
|
|
/* Avoid waking kswapd by allocating pages_to_migrate pages. */
|
|
if (!zone_watermark_ok(zone, 0,
|
|
high_wmark_pages(zone) +
|
|
nr_migrate_pages,
|
|
ZONE_MOVABLE, 0))
|
|
continue;
|
|
return true;
|
|
}
|
|
return false;
|
|
}
|
|
|
|
static struct folio *alloc_misplaced_dst_folio(struct folio *src,
|
|
unsigned long data)
|
|
{
|
|
int nid = (int) data;
|
|
int order = folio_order(src);
|
|
gfp_t gfp = __GFP_THISNODE;
|
|
|
|
if (order > 0)
|
|
gfp |= GFP_TRANSHUGE_LIGHT;
|
|
else {
|
|
gfp |= GFP_HIGHUSER_MOVABLE | __GFP_NOMEMALLOC | __GFP_NORETRY |
|
|
__GFP_NOWARN;
|
|
gfp &= ~__GFP_RECLAIM;
|
|
}
|
|
return __folio_alloc_node(gfp, order, nid);
|
|
}
|
|
|
|
static int numamigrate_isolate_folio(pg_data_t *pgdat, struct folio *folio)
|
|
{
|
|
int nr_pages = folio_nr_pages(folio);
|
|
|
|
/* Avoid migrating to a node that is nearly full */
|
|
if (!migrate_balanced_pgdat(pgdat, nr_pages)) {
|
|
int z;
|
|
|
|
if (!(sysctl_numa_balancing_mode & NUMA_BALANCING_MEMORY_TIERING))
|
|
return 0;
|
|
for (z = pgdat->nr_zones - 1; z >= 0; z--) {
|
|
if (managed_zone(pgdat->node_zones + z))
|
|
break;
|
|
}
|
|
|
|
/*
|
|
* If there are no managed zones, it should not proceed
|
|
* further.
|
|
*/
|
|
if (z < 0)
|
|
return 0;
|
|
|
|
wakeup_kswapd(pgdat->node_zones + z, 0,
|
|
folio_order(folio), ZONE_MOVABLE);
|
|
return 0;
|
|
}
|
|
|
|
if (!folio_isolate_lru(folio))
|
|
return 0;
|
|
|
|
node_stat_mod_folio(folio, NR_ISOLATED_ANON + folio_is_file_lru(folio),
|
|
nr_pages);
|
|
|
|
/*
|
|
* Isolating the folio has taken another reference, so the
|
|
* caller's reference can be safely dropped without the folio
|
|
* disappearing underneath us during migration.
|
|
*/
|
|
folio_put(folio);
|
|
return 1;
|
|
}
|
|
|
|
/*
|
|
* Attempt to migrate a misplaced folio to the specified destination
|
|
* node. Caller is expected to have an elevated reference count on
|
|
* the folio that will be dropped by this function before returning.
|
|
*/
|
|
int migrate_misplaced_folio(struct folio *folio, struct vm_area_struct *vma,
|
|
int node)
|
|
{
|
|
pg_data_t *pgdat = NODE_DATA(node);
|
|
int isolated;
|
|
int nr_remaining;
|
|
unsigned int nr_succeeded;
|
|
LIST_HEAD(migratepages);
|
|
int nr_pages = folio_nr_pages(folio);
|
|
|
|
/*
|
|
* Don't migrate file folios that are mapped in multiple processes
|
|
* with execute permissions as they are probably shared libraries.
|
|
* To check if the folio is shared, ideally we want to make sure
|
|
* every page is mapped to the same process. Doing that is very
|
|
* expensive, so check the estimated mapcount of the folio instead.
|
|
*/
|
|
if (folio_estimated_sharers(folio) != 1 && folio_is_file_lru(folio) &&
|
|
(vma->vm_flags & VM_EXEC))
|
|
goto out;
|
|
|
|
/*
|
|
* Also do not migrate dirty folios as not all filesystems can move
|
|
* dirty folios in MIGRATE_ASYNC mode which is a waste of cycles.
|
|
*/
|
|
if (folio_is_file_lru(folio) && folio_test_dirty(folio))
|
|
goto out;
|
|
|
|
isolated = numamigrate_isolate_folio(pgdat, folio);
|
|
if (!isolated)
|
|
goto out;
|
|
|
|
list_add(&folio->lru, &migratepages);
|
|
nr_remaining = migrate_pages(&migratepages, alloc_misplaced_dst_folio,
|
|
NULL, node, MIGRATE_ASYNC,
|
|
MR_NUMA_MISPLACED, &nr_succeeded);
|
|
if (nr_remaining) {
|
|
if (!list_empty(&migratepages)) {
|
|
list_del(&folio->lru);
|
|
node_stat_mod_folio(folio, NR_ISOLATED_ANON +
|
|
folio_is_file_lru(folio), -nr_pages);
|
|
folio_putback_lru(folio);
|
|
}
|
|
isolated = 0;
|
|
}
|
|
if (nr_succeeded) {
|
|
count_vm_numa_events(NUMA_PAGE_MIGRATE, nr_succeeded);
|
|
if (!node_is_toptier(folio_nid(folio)) && node_is_toptier(node))
|
|
mod_node_page_state(pgdat, PGPROMOTE_SUCCESS,
|
|
nr_succeeded);
|
|
}
|
|
BUG_ON(!list_empty(&migratepages));
|
|
return isolated;
|
|
|
|
out:
|
|
folio_put(folio);
|
|
return 0;
|
|
}
|
|
#endif /* CONFIG_NUMA_BALANCING */
|
|
#endif /* CONFIG_NUMA */
|