3364 lines
88 KiB
C
3364 lines
88 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/pagevec.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/pagewalk.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/mmu_notifier.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 <asm/tlbflush.h>
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#define CREATE_TRACE_POINTS
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#include <trace/events/migrate.h>
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#include "internal.h"
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int isolate_movable_page(struct page *page, isolate_mode_t mode)
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{
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struct address_space *mapping;
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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 (unlikely(!get_page_unless_zero(page)))
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goto out;
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/*
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* Check PageMovable before holding a PG_lock because page's owner
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* assumes anybody doesn't touch PG_lock of newly allocated page
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* so unconditionally grabbing the lock ruins page's owner side.
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*/
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if (unlikely(!__PageMovable(page)))
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goto out_putpage;
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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(!trylock_page(page)))
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goto out_putpage;
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if (!PageMovable(page) || PageIsolated(page))
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goto out_no_isolated;
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mapping = page_mapping(page);
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VM_BUG_ON_PAGE(!mapping, page);
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if (!mapping->a_ops->isolate_page(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(PageIsolated(page));
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__SetPageIsolated(page);
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unlock_page(page);
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return 0;
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out_no_isolated:
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unlock_page(page);
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out_putpage:
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put_page(page);
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out:
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return -EBUSY;
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}
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static void putback_movable_page(struct page *page)
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{
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struct address_space *mapping;
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mapping = page_mapping(page);
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mapping->a_ops->putback_page(page);
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__ClearPageIsolated(page);
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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_huge_page().
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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 page *page;
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struct page *page2;
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list_for_each_entry_safe(page, page2, l, lru) {
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if (unlikely(PageHuge(page))) {
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putback_active_hugepage(page);
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continue;
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}
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list_del(&page->lru);
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/*
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* We isolated non-lru movable page so here we can use
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* __PageMovable because LRU page's mapping cannot have
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* PAGE_MAPPING_MOVABLE.
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*/
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if (unlikely(__PageMovable(page))) {
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VM_BUG_ON_PAGE(!PageIsolated(page), page);
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lock_page(page);
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if (PageMovable(page))
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putback_movable_page(page);
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else
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__ClearPageIsolated(page);
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unlock_page(page);
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put_page(page);
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} else {
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mod_node_page_state(page_pgdat(page), NR_ISOLATED_ANON +
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page_is_file_lru(page), -thp_nr_pages(page));
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putback_lru_page(page);
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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 page *page, struct vm_area_struct *vma,
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unsigned long addr, void *old)
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{
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struct page_vma_mapped_walk pvmw = {
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.page = old,
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.vma = vma,
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.address = addr,
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.flags = PVMW_SYNC | PVMW_MIGRATION,
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};
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struct page *new;
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pte_t pte;
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swp_entry_t entry;
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VM_BUG_ON_PAGE(PageTail(page), page);
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while (page_vma_mapped_walk(&pvmw)) {
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if (PageKsm(page))
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new = page;
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else
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new = page - pvmw.page->index +
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linear_page_index(vma, pvmw.address);
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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_PAGE(PageHuge(page) || !PageTransCompound(page), page);
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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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get_page(new);
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pte = pte_mkold(mk_pte(new, READ_ONCE(vma->vm_page_prot)));
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if (pte_swp_soft_dirty(*pvmw.pte))
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pte = pte_mksoft_dirty(pte);
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/*
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* Recheck VMA as permissions can change since migration started
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*/
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entry = pte_to_swp_entry(*pvmw.pte);
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if (is_writable_migration_entry(entry))
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pte = maybe_mkwrite(pte, vma);
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else if (pte_swp_uffd_wp(*pvmw.pte))
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pte = pte_mkuffd_wp(pte);
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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(*pvmw.pte))
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pte = pte_swp_mksoft_dirty(pte);
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if (pte_swp_uffd_wp(*pvmw.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 (PageHuge(new)) {
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unsigned int shift = huge_page_shift(hstate_vma(vma));
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pte = pte_mkhuge(pte);
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pte = arch_make_huge_pte(pte, shift, vma->vm_flags);
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if (PageAnon(new))
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hugepage_add_anon_rmap(new, vma, pvmw.address);
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else
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page_dup_rmap(new, true);
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set_huge_pte_at(vma->vm_mm, pvmw.address, pvmw.pte, pte);
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} else
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#endif
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{
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if (PageAnon(new))
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page_add_anon_rmap(new, vma, pvmw.address, false);
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else
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page_add_file_rmap(new, false);
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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 && !PageTransCompound(new))
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mlock_vma_page(new);
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if (PageTransHuge(page) && PageMlocked(page))
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clear_page_mlock(page);
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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 page *old, struct page *new, 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 = old,
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};
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if (locked)
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rmap_walk_locked(new, &rwc);
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else
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rmap_walk(new, &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, pte_t *ptep,
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spinlock_t *ptl)
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{
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pte_t pte;
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swp_entry_t entry;
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spin_lock(ptl);
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pte = *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, ptep, ptl);
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return;
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out:
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pte_unmap_unlock(ptep, ptl);
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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 = pte_lockptr(mm, pmd);
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pte_t *ptep = pte_offset_map(pmd, address);
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__migration_entry_wait(mm, ptep, ptl);
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}
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void migration_entry_wait_huge(struct vm_area_struct *vma,
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struct mm_struct *mm, pte_t *pte)
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{
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spinlock_t *ptl = huge_pte_lockptr(hstate_vma(vma), mm, pte);
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__migration_entry_wait(mm, pte, ptl);
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}
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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), NULL, 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 expected_page_refs(struct address_space *mapping, struct page *page)
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{
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int expected_count = 1;
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/*
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* Device private pages have an extra refcount as they are
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* ZONE_DEVICE pages.
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*/
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expected_count += is_device_private_page(page);
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if (mapping)
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expected_count += compound_nr(page) + page_has_private(page);
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return expected_count;
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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 = expected_page_refs(mapping, &folio->page) + extra_count;
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long nr = folio_nr_pages(folio);
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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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} else {
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VM_BUG_ON_FOLIO(folio_test_swapcache(folio), folio);
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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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xas_store(&xas, newfolio);
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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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xas_unlock(&xas);
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/* Leave irq disabled to prevent preemption while updating stats */
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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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__mod_lruvec_state(old_lruvec, NR_FILE_PAGES, -nr);
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__mod_lruvec_state(new_lruvec, NR_FILE_PAGES, nr);
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if (folio_test_swapbacked(folio) && !folio_test_swapcache(folio)) {
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__mod_lruvec_state(old_lruvec, NR_SHMEM, -nr);
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__mod_lruvec_state(new_lruvec, NR_SHMEM, nr);
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}
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#ifdef CONFIG_SWAP
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if (folio_test_swapcache(folio)) {
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__mod_lruvec_state(old_lruvec, NR_SWAPCACHE, -nr);
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__mod_lruvec_state(new_lruvec, NR_SWAPCACHE, nr);
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}
|
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#endif
|
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if (dirty && mapping_can_writeback(mapping)) {
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__mod_lruvec_state(old_lruvec, NR_FILE_DIRTY, -nr);
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__mod_zone_page_state(oldzone, NR_ZONE_WRITE_PENDING, -nr);
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__mod_lruvec_state(new_lruvec, NR_FILE_DIRTY, nr);
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__mod_zone_page_state(newzone, NR_ZONE_WRITE_PENDING, nr);
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}
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}
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local_irq_enable();
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return MIGRATEPAGE_SUCCESS;
|
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}
|
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EXPORT_SYMBOL(folio_migrate_mapping);
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|
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/*
|
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* The expected number of remaining references is the same as that
|
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* of folio_migrate_mapping().
|
|
*/
|
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int migrate_huge_page_move_mapping(struct address_space *mapping,
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struct page *newpage, struct page *page)
|
|
{
|
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XA_STATE(xas, &mapping->i_pages, page_index(page));
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int expected_count;
|
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|
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xas_lock_irq(&xas);
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expected_count = 2 + page_has_private(page);
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if (page_count(page) != expected_count || xas_load(&xas) != page) {
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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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if (!page_ref_freeze(page, 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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newpage->index = page->index;
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newpage->mapping = page->mapping;
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|
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get_page(newpage);
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|
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xas_store(&xas, newpage);
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|
|
page_ref_unfreeze(page, expected_count - 1);
|
|
|
|
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);
|
|
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 = page_cpupid_xchg_last(&folio->page, -1);
|
|
page_cpupid_xchg_last(&newfolio->page, 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);
|
|
|
|
if (!folio_test_hugetlb(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
|
|
***********************************************************/
|
|
|
|
/*
|
|
* Common logic to directly migrate a single LRU page suitable for
|
|
* pages that do not use PagePrivate/PagePrivate2.
|
|
*
|
|
* Pages are locked upon entry and exit.
|
|
*/
|
|
int migrate_page(struct address_space *mapping,
|
|
struct page *newpage, struct page *page,
|
|
enum migrate_mode mode)
|
|
{
|
|
struct folio *newfolio = page_folio(newpage);
|
|
struct folio *folio = page_folio(page);
|
|
int rc;
|
|
|
|
BUG_ON(folio_test_writeback(folio)); /* Writeback must be complete */
|
|
|
|
rc = folio_migrate_mapping(mapping, newfolio, folio, 0);
|
|
|
|
if (rc != MIGRATEPAGE_SUCCESS)
|
|
return rc;
|
|
|
|
if (mode != MIGRATE_SYNC_NO_COPY)
|
|
folio_migrate_copy(newfolio, folio);
|
|
else
|
|
folio_migrate_flags(newfolio, folio);
|
|
return MIGRATEPAGE_SUCCESS;
|
|
}
|
|
EXPORT_SYMBOL(migrate_page);
|
|
|
|
#ifdef CONFIG_BLOCK
|
|
/* 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;
|
|
|
|
/* Simple case, sync compaction */
|
|
if (mode != MIGRATE_ASYNC) {
|
|
do {
|
|
lock_buffer(bh);
|
|
bh = bh->b_this_page;
|
|
|
|
} while (bh != head);
|
|
|
|
return true;
|
|
}
|
|
|
|
/* async case, we cannot block on lock_buffer so use trylock_buffer */
|
|
do {
|
|
if (!trylock_buffer(bh)) {
|
|
/*
|
|
* We failed to lock the buffer and cannot stall in
|
|
* async migration. Release the taken locks
|
|
*/
|
|
struct buffer_head *failed_bh = bh;
|
|
bh = head;
|
|
while (bh != failed_bh) {
|
|
unlock_buffer(bh);
|
|
bh = bh->b_this_page;
|
|
}
|
|
return false;
|
|
}
|
|
|
|
bh = bh->b_this_page;
|
|
} while (bh != head);
|
|
return true;
|
|
}
|
|
|
|
static int __buffer_migrate_page(struct address_space *mapping,
|
|
struct page *newpage, struct page *page, enum migrate_mode mode,
|
|
bool check_refs)
|
|
{
|
|
struct buffer_head *bh, *head;
|
|
int rc;
|
|
int expected_count;
|
|
|
|
if (!page_has_buffers(page))
|
|
return migrate_page(mapping, newpage, page, mode);
|
|
|
|
/* Check whether page does not have extra refs before we do more work */
|
|
expected_count = expected_page_refs(mapping, page);
|
|
if (page_count(page) != expected_count)
|
|
return -EAGAIN;
|
|
|
|
head = page_buffers(page);
|
|
if (!buffer_migrate_lock_buffers(head, mode))
|
|
return -EAGAIN;
|
|
|
|
if (check_refs) {
|
|
bool busy;
|
|
bool invalidated = false;
|
|
|
|
recheck_buffers:
|
|
busy = false;
|
|
spin_lock(&mapping->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->private_lock);
|
|
invalidate_bh_lrus();
|
|
invalidated = true;
|
|
goto recheck_buffers;
|
|
}
|
|
}
|
|
|
|
rc = migrate_page_move_mapping(mapping, newpage, page, 0);
|
|
if (rc != MIGRATEPAGE_SUCCESS)
|
|
goto unlock_buffers;
|
|
|
|
attach_page_private(newpage, detach_page_private(page));
|
|
|
|
bh = head;
|
|
do {
|
|
set_bh_page(bh, newpage, bh_offset(bh));
|
|
bh = bh->b_this_page;
|
|
|
|
} while (bh != head);
|
|
|
|
if (mode != MIGRATE_SYNC_NO_COPY)
|
|
migrate_page_copy(newpage, page);
|
|
else
|
|
migrate_page_states(newpage, page);
|
|
|
|
rc = MIGRATEPAGE_SUCCESS;
|
|
unlock_buffers:
|
|
if (check_refs)
|
|
spin_unlock(&mapping->private_lock);
|
|
bh = head;
|
|
do {
|
|
unlock_buffer(bh);
|
|
bh = bh->b_this_page;
|
|
|
|
} while (bh != head);
|
|
|
|
return rc;
|
|
}
|
|
|
|
/*
|
|
* Migration function for pages with buffers. This function can only be used
|
|
* if the underlying filesystem guarantees that no other references to "page"
|
|
* exist. For example attached buffer heads are accessed only under page lock.
|
|
*/
|
|
int buffer_migrate_page(struct address_space *mapping,
|
|
struct page *newpage, struct page *page, enum migrate_mode mode)
|
|
{
|
|
return __buffer_migrate_page(mapping, newpage, page, mode, false);
|
|
}
|
|
EXPORT_SYMBOL(buffer_migrate_page);
|
|
|
|
/*
|
|
* Same as above 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).
|
|
*/
|
|
int buffer_migrate_page_norefs(struct address_space *mapping,
|
|
struct page *newpage, struct page *page, enum migrate_mode mode)
|
|
{
|
|
return __buffer_migrate_page(mapping, newpage, page, mode, true);
|
|
}
|
|
#endif
|
|
|
|
/*
|
|
* Writeback a page to clean the dirty state
|
|
*/
|
|
static int writeout(struct address_space *mapping, struct page *page)
|
|
{
|
|
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 (!clear_page_dirty_for_io(page))
|
|
/* Someone else already triggered a write */
|
|
return -EAGAIN;
|
|
|
|
/*
|
|
* A dirty page may imply that the underlying filesystem has
|
|
* the page on some queue. So the page must be clean for
|
|
* migration. Writeout may mean we loose the lock and the
|
|
* page state is no longer what we checked for earlier.
|
|
* At this point we know that the migration attempt cannot
|
|
* be successful.
|
|
*/
|
|
remove_migration_ptes(page, page, false);
|
|
|
|
rc = mapping->a_ops->writepage(page, &wbc);
|
|
|
|
if (rc != AOP_WRITEPAGE_ACTIVATE)
|
|
/* unlocked. Relock */
|
|
lock_page(page);
|
|
|
|
return (rc < 0) ? -EIO : -EAGAIN;
|
|
}
|
|
|
|
/*
|
|
* Default handling if a filesystem does not provide a migration function.
|
|
*/
|
|
static int fallback_migrate_page(struct address_space *mapping,
|
|
struct page *newpage, struct page *page, enum migrate_mode mode)
|
|
{
|
|
if (PageDirty(page)) {
|
|
/* Only writeback pages in full synchronous migration */
|
|
switch (mode) {
|
|
case MIGRATE_SYNC:
|
|
case MIGRATE_SYNC_NO_COPY:
|
|
break;
|
|
default:
|
|
return -EBUSY;
|
|
}
|
|
return writeout(mapping, page);
|
|
}
|
|
|
|
/*
|
|
* Buffers may be managed in a filesystem specific way.
|
|
* We must have no buffers or drop them.
|
|
*/
|
|
if (page_has_private(page) &&
|
|
!try_to_release_page(page, GFP_KERNEL))
|
|
return mode == MIGRATE_SYNC ? -EAGAIN : -EBUSY;
|
|
|
|
return migrate_page(mapping, newpage, page, 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_page(struct page *newpage, struct page *page,
|
|
enum migrate_mode mode)
|
|
{
|
|
struct address_space *mapping;
|
|
int rc = -EAGAIN;
|
|
bool is_lru = !__PageMovable(page);
|
|
|
|
VM_BUG_ON_PAGE(!PageLocked(page), page);
|
|
VM_BUG_ON_PAGE(!PageLocked(newpage), newpage);
|
|
|
|
mapping = page_mapping(page);
|
|
|
|
if (likely(is_lru)) {
|
|
if (!mapping)
|
|
rc = migrate_page(mapping, newpage, page, mode);
|
|
else if (mapping->a_ops->migratepage)
|
|
/*
|
|
* Most pages have a mapping and most filesystems
|
|
* provide a migratepage callback. Anonymous pages
|
|
* are part of swap space which also has its own
|
|
* migratepage callback. This is the most common path
|
|
* for page migration.
|
|
*/
|
|
rc = mapping->a_ops->migratepage(mapping, newpage,
|
|
page, mode);
|
|
else
|
|
rc = fallback_migrate_page(mapping, newpage,
|
|
page, mode);
|
|
} else {
|
|
/*
|
|
* In case of non-lru page, it could be released after
|
|
* isolation step. In that case, we shouldn't try migration.
|
|
*/
|
|
VM_BUG_ON_PAGE(!PageIsolated(page), page);
|
|
if (!PageMovable(page)) {
|
|
rc = MIGRATEPAGE_SUCCESS;
|
|
__ClearPageIsolated(page);
|
|
goto out;
|
|
}
|
|
|
|
rc = mapping->a_ops->migratepage(mapping, newpage,
|
|
page, mode);
|
|
WARN_ON_ONCE(rc == MIGRATEPAGE_SUCCESS &&
|
|
!PageIsolated(page));
|
|
}
|
|
|
|
/*
|
|
* When successful, old pagecache page->mapping must be cleared before
|
|
* page is freed; but stats require that PageAnon be left as PageAnon.
|
|
*/
|
|
if (rc == MIGRATEPAGE_SUCCESS) {
|
|
if (__PageMovable(page)) {
|
|
VM_BUG_ON_PAGE(!PageIsolated(page), page);
|
|
|
|
/*
|
|
* We clear PG_movable under page_lock so any compactor
|
|
* cannot try to migrate this page.
|
|
*/
|
|
__ClearPageIsolated(page);
|
|
}
|
|
|
|
/*
|
|
* Anonymous and movable page->mapping will be cleared by
|
|
* free_pages_prepare so don't reset it here for keeping
|
|
* the type to work PageAnon, for example.
|
|
*/
|
|
if (!PageMappingFlags(page))
|
|
page->mapping = NULL;
|
|
|
|
if (likely(!is_zone_device_page(newpage)))
|
|
flush_dcache_page(newpage);
|
|
|
|
}
|
|
out:
|
|
return rc;
|
|
}
|
|
|
|
static int __unmap_and_move(struct page *page, struct page *newpage,
|
|
int force, enum migrate_mode mode)
|
|
{
|
|
int rc = -EAGAIN;
|
|
bool page_was_mapped = false;
|
|
struct anon_vma *anon_vma = NULL;
|
|
bool is_lru = !__PageMovable(page);
|
|
|
|
if (!trylock_page(page)) {
|
|
if (!force || 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;
|
|
|
|
lock_page(page);
|
|
}
|
|
|
|
if (PageWriteback(page)) {
|
|
/*
|
|
* 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_unlock;
|
|
}
|
|
if (!force)
|
|
goto out_unlock;
|
|
wait_on_page_writeback(page);
|
|
}
|
|
|
|
/*
|
|
* By try_to_migrate(), page->mapcount goes down to 0 here. In this case,
|
|
* we cannot notice that anon_vma is freed while we migrates 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 page_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 (PageAnon(page) && !PageKsm(page))
|
|
anon_vma = page_get_anon_vma(page);
|
|
|
|
/*
|
|
* 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 newpage at this point. We used to have a BUG
|
|
* here if trylock_page(newpage) fails, but would like to allow for
|
|
* cases where there might be a race with the previous use of newpage.
|
|
* This is much like races on refcount of oldpage: just don't BUG().
|
|
*/
|
|
if (unlikely(!trylock_page(newpage)))
|
|
goto out_unlock;
|
|
|
|
if (unlikely(!is_lru)) {
|
|
rc = move_to_new_page(newpage, page, mode);
|
|
goto out_unlock_both;
|
|
}
|
|
|
|
/*
|
|
* 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 page->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 (!page->mapping) {
|
|
VM_BUG_ON_PAGE(PageAnon(page), page);
|
|
if (page_has_private(page)) {
|
|
try_to_free_buffers(page);
|
|
goto out_unlock_both;
|
|
}
|
|
} else if (page_mapped(page)) {
|
|
/* Establish migration ptes */
|
|
VM_BUG_ON_PAGE(PageAnon(page) && !PageKsm(page) && !anon_vma,
|
|
page);
|
|
try_to_migrate(page, 0);
|
|
page_was_mapped = true;
|
|
}
|
|
|
|
if (!page_mapped(page))
|
|
rc = move_to_new_page(newpage, page, mode);
|
|
|
|
if (page_was_mapped)
|
|
remove_migration_ptes(page,
|
|
rc == MIGRATEPAGE_SUCCESS ? newpage : page, false);
|
|
|
|
out_unlock_both:
|
|
unlock_page(newpage);
|
|
out_unlock:
|
|
/* Drop an anon_vma reference if we took one */
|
|
if (anon_vma)
|
|
put_anon_vma(anon_vma);
|
|
unlock_page(page);
|
|
out:
|
|
/*
|
|
* If migration is successful, decrease refcount of the newpage
|
|
* which will not free the page because new page owner increased
|
|
* refcounter. As well, if it is LRU page, add the page to LRU
|
|
* list in here. Use the old state of the isolated source page to
|
|
* determine if we migrated a LRU page. newpage was already unlocked
|
|
* and possibly modified by its owner - don't rely on the page
|
|
* state.
|
|
*/
|
|
if (rc == MIGRATEPAGE_SUCCESS) {
|
|
if (unlikely(!is_lru))
|
|
put_page(newpage);
|
|
else
|
|
putback_lru_page(newpage);
|
|
}
|
|
|
|
return rc;
|
|
}
|
|
|
|
/*
|
|
* Obtain the lock on page, remove all ptes and migrate the page
|
|
* to the newly allocated page in newpage.
|
|
*/
|
|
static int unmap_and_move(new_page_t get_new_page,
|
|
free_page_t put_new_page,
|
|
unsigned long private, struct page *page,
|
|
int force, enum migrate_mode mode,
|
|
enum migrate_reason reason,
|
|
struct list_head *ret)
|
|
{
|
|
int rc = MIGRATEPAGE_SUCCESS;
|
|
struct page *newpage = NULL;
|
|
|
|
if (!thp_migration_supported() && PageTransHuge(page))
|
|
return -ENOSYS;
|
|
|
|
if (page_count(page) == 1) {
|
|
/* page was freed from under us. So we are done. */
|
|
ClearPageActive(page);
|
|
ClearPageUnevictable(page);
|
|
if (unlikely(__PageMovable(page))) {
|
|
lock_page(page);
|
|
if (!PageMovable(page))
|
|
__ClearPageIsolated(page);
|
|
unlock_page(page);
|
|
}
|
|
goto out;
|
|
}
|
|
|
|
newpage = get_new_page(page, private);
|
|
if (!newpage)
|
|
return -ENOMEM;
|
|
|
|
rc = __unmap_and_move(page, newpage, force, mode);
|
|
if (rc == MIGRATEPAGE_SUCCESS)
|
|
set_page_owner_migrate_reason(newpage, reason);
|
|
|
|
out:
|
|
if (rc != -EAGAIN) {
|
|
/*
|
|
* A page that has been migrated has all references
|
|
* removed and will be freed. A page that has not been
|
|
* migrated will have kept its references and be restored.
|
|
*/
|
|
list_del(&page->lru);
|
|
}
|
|
|
|
/*
|
|
* If migration is successful, releases reference grabbed during
|
|
* isolation. Otherwise, restore the page to right list unless
|
|
* we want to retry.
|
|
*/
|
|
if (rc == MIGRATEPAGE_SUCCESS) {
|
|
/*
|
|
* Compaction can migrate also non-LRU pages which are
|
|
* not accounted to NR_ISOLATED_*. They can be recognized
|
|
* as __PageMovable
|
|
*/
|
|
if (likely(!__PageMovable(page)))
|
|
mod_node_page_state(page_pgdat(page), NR_ISOLATED_ANON +
|
|
page_is_file_lru(page), -thp_nr_pages(page));
|
|
|
|
if (reason != MR_MEMORY_FAILURE)
|
|
/*
|
|
* We release the page in page_handle_poison.
|
|
*/
|
|
put_page(page);
|
|
} else {
|
|
if (rc != -EAGAIN)
|
|
list_add_tail(&page->lru, ret);
|
|
|
|
if (put_new_page)
|
|
put_new_page(newpage, private);
|
|
else
|
|
put_page(newpage);
|
|
}
|
|
|
|
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_page_t get_new_page,
|
|
free_page_t put_new_page, unsigned long private,
|
|
struct page *hpage, int force,
|
|
enum migrate_mode mode, int reason,
|
|
struct list_head *ret)
|
|
{
|
|
int rc = -EAGAIN;
|
|
int page_was_mapped = 0;
|
|
struct page *new_hpage;
|
|
struct anon_vma *anon_vma = NULL;
|
|
struct address_space *mapping = NULL;
|
|
|
|
/*
|
|
* 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(page_hstate(hpage))) {
|
|
list_move_tail(&hpage->lru, ret);
|
|
return -ENOSYS;
|
|
}
|
|
|
|
if (page_count(hpage) == 1) {
|
|
/* page was freed from under us. So we are done. */
|
|
putback_active_hugepage(hpage);
|
|
return MIGRATEPAGE_SUCCESS;
|
|
}
|
|
|
|
new_hpage = get_new_page(hpage, private);
|
|
if (!new_hpage)
|
|
return -ENOMEM;
|
|
|
|
if (!trylock_page(hpage)) {
|
|
if (!force)
|
|
goto out;
|
|
switch (mode) {
|
|
case MIGRATE_SYNC:
|
|
case MIGRATE_SYNC_NO_COPY:
|
|
break;
|
|
default:
|
|
goto out;
|
|
}
|
|
lock_page(hpage);
|
|
}
|
|
|
|
/*
|
|
* Check for pages which are in the process of being freed. Without
|
|
* page_mapping() set, hugetlbfs specific move page routine will not
|
|
* be called and we could leak usage counts for subpools.
|
|
*/
|
|
if (hugetlb_page_subpool(hpage) && !page_mapping(hpage)) {
|
|
rc = -EBUSY;
|
|
goto out_unlock;
|
|
}
|
|
|
|
if (PageAnon(hpage))
|
|
anon_vma = page_get_anon_vma(hpage);
|
|
|
|
if (unlikely(!trylock_page(new_hpage)))
|
|
goto put_anon;
|
|
|
|
if (page_mapped(hpage)) {
|
|
bool mapping_locked = false;
|
|
enum ttu_flags ttu = 0;
|
|
|
|
if (!PageAnon(hpage)) {
|
|
/*
|
|
* 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(hpage);
|
|
if (unlikely(!mapping))
|
|
goto unlock_put_anon;
|
|
|
|
mapping_locked = true;
|
|
ttu |= TTU_RMAP_LOCKED;
|
|
}
|
|
|
|
try_to_migrate(hpage, ttu);
|
|
page_was_mapped = 1;
|
|
|
|
if (mapping_locked)
|
|
i_mmap_unlock_write(mapping);
|
|
}
|
|
|
|
if (!page_mapped(hpage))
|
|
rc = move_to_new_page(new_hpage, hpage, mode);
|
|
|
|
if (page_was_mapped)
|
|
remove_migration_ptes(hpage,
|
|
rc == MIGRATEPAGE_SUCCESS ? new_hpage : hpage, false);
|
|
|
|
unlock_put_anon:
|
|
unlock_page(new_hpage);
|
|
|
|
put_anon:
|
|
if (anon_vma)
|
|
put_anon_vma(anon_vma);
|
|
|
|
if (rc == MIGRATEPAGE_SUCCESS) {
|
|
move_hugetlb_state(hpage, new_hpage, reason);
|
|
put_new_page = NULL;
|
|
}
|
|
|
|
out_unlock:
|
|
unlock_page(hpage);
|
|
out:
|
|
if (rc == MIGRATEPAGE_SUCCESS)
|
|
putback_active_hugepage(hpage);
|
|
else if (rc != -EAGAIN)
|
|
list_move_tail(&hpage->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_page)
|
|
put_new_page(new_hpage, private);
|
|
else
|
|
putback_active_hugepage(new_hpage);
|
|
|
|
return rc;
|
|
}
|
|
|
|
static inline int try_split_thp(struct page *page, struct page **page2,
|
|
struct list_head *from)
|
|
{
|
|
int rc = 0;
|
|
|
|
lock_page(page);
|
|
rc = split_huge_page_to_list(page, from);
|
|
unlock_page(page);
|
|
if (!rc)
|
|
list_safe_reset_next(page, *page2, lru);
|
|
|
|
return rc;
|
|
}
|
|
|
|
/*
|
|
* migrate_pages - migrate the pages specified in a list, to the free pages
|
|
* supplied as the target for the page migration
|
|
*
|
|
* @from: The list of pages to be migrated.
|
|
* @get_new_page: The function used to allocate free pages to be used
|
|
* as the target of the page migration.
|
|
* @put_new_page: The function used to free target pages if migration
|
|
* fails, or NULL if no special handling is necessary.
|
|
* @private: Private data to be passed on to get_new_page()
|
|
* @mode: The migration mode that specifies the constraints for
|
|
* page migration, if any.
|
|
* @reason: The reason for page migration.
|
|
* @ret_succeeded: Set to the number of normal pages migrated successfully if
|
|
* the caller passes a non-NULL pointer.
|
|
*
|
|
* The function returns after 10 attempts or if no pages are movable any more
|
|
* because the list has become empty or no retryable pages exist any more.
|
|
* It is caller's responsibility to call putback_movable_pages() to return pages
|
|
* to the LRU or free list only if ret != 0.
|
|
*
|
|
* Returns the number of {normal page, THP, hugetlb} that were not migrated, or
|
|
* an error code. The number of THP splits will be considered as the number of
|
|
* non-migrated THP, no matter how many subpages of the THP are migrated successfully.
|
|
*/
|
|
int migrate_pages(struct list_head *from, new_page_t get_new_page,
|
|
free_page_t put_new_page, unsigned long private,
|
|
enum migrate_mode mode, int reason, unsigned int *ret_succeeded)
|
|
{
|
|
int retry = 1;
|
|
int thp_retry = 1;
|
|
int nr_failed = 0;
|
|
int nr_failed_pages = 0;
|
|
int nr_succeeded = 0;
|
|
int nr_thp_succeeded = 0;
|
|
int nr_thp_failed = 0;
|
|
int nr_thp_split = 0;
|
|
int pass = 0;
|
|
bool is_thp = false;
|
|
struct page *page;
|
|
struct page *page2;
|
|
int swapwrite = current->flags & PF_SWAPWRITE;
|
|
int rc, nr_subpages;
|
|
LIST_HEAD(ret_pages);
|
|
LIST_HEAD(thp_split_pages);
|
|
bool nosplit = (reason == MR_NUMA_MISPLACED);
|
|
bool no_subpage_counting = false;
|
|
|
|
trace_mm_migrate_pages_start(mode, reason);
|
|
|
|
if (!swapwrite)
|
|
current->flags |= PF_SWAPWRITE;
|
|
|
|
thp_subpage_migration:
|
|
for (pass = 0; pass < 10 && (retry || thp_retry); pass++) {
|
|
retry = 0;
|
|
thp_retry = 0;
|
|
|
|
list_for_each_entry_safe(page, page2, from, lru) {
|
|
retry:
|
|
/*
|
|
* THP statistics is based on the source huge page.
|
|
* Capture required information that might get lost
|
|
* during migration.
|
|
*/
|
|
is_thp = PageTransHuge(page) && !PageHuge(page);
|
|
nr_subpages = compound_nr(page);
|
|
cond_resched();
|
|
|
|
if (PageHuge(page))
|
|
rc = unmap_and_move_huge_page(get_new_page,
|
|
put_new_page, private, page,
|
|
pass > 2, mode, reason,
|
|
&ret_pages);
|
|
else
|
|
rc = unmap_and_move(get_new_page, put_new_page,
|
|
private, page, pass > 2, mode,
|
|
reason, &ret_pages);
|
|
/*
|
|
* The rules are:
|
|
* Success: non hugetlb page will be freed, hugetlb
|
|
* page will be put back
|
|
* -EAGAIN: stay on the from list
|
|
* -ENOMEM: stay on the from list
|
|
* Other errno: put on ret_pages list then splice to
|
|
* from list
|
|
*/
|
|
switch(rc) {
|
|
/*
|
|
* THP migration might be unsupported or the
|
|
* allocation could've failed so we should
|
|
* retry on the same page with the THP split
|
|
* to base pages.
|
|
*
|
|
* Head page is retried immediately and tail
|
|
* pages are added to the tail of the list so
|
|
* we encounter them after the rest of the list
|
|
* is processed.
|
|
*/
|
|
case -ENOSYS:
|
|
/* THP migration is unsupported */
|
|
if (is_thp) {
|
|
nr_thp_failed++;
|
|
if (!try_split_thp(page, &page2, &thp_split_pages)) {
|
|
nr_thp_split++;
|
|
goto retry;
|
|
}
|
|
|
|
nr_failed_pages += nr_subpages;
|
|
break;
|
|
}
|
|
|
|
/* Hugetlb migration is unsupported */
|
|
if (!no_subpage_counting)
|
|
nr_failed++;
|
|
nr_failed_pages += nr_subpages;
|
|
break;
|
|
case -ENOMEM:
|
|
/*
|
|
* When memory is low, don't bother to try to migrate
|
|
* other pages, just exit.
|
|
* THP NUMA faulting doesn't split THP to retry.
|
|
*/
|
|
if (is_thp && !nosplit) {
|
|
nr_thp_failed++;
|
|
if (!try_split_thp(page, &page2, &thp_split_pages)) {
|
|
nr_thp_split++;
|
|
goto retry;
|
|
}
|
|
|
|
nr_failed_pages += nr_subpages;
|
|
goto out;
|
|
}
|
|
|
|
if (!no_subpage_counting)
|
|
nr_failed++;
|
|
nr_failed_pages += nr_subpages;
|
|
goto out;
|
|
case -EAGAIN:
|
|
if (is_thp) {
|
|
thp_retry++;
|
|
break;
|
|
}
|
|
retry++;
|
|
break;
|
|
case MIGRATEPAGE_SUCCESS:
|
|
nr_succeeded += nr_subpages;
|
|
if (is_thp) {
|
|
nr_thp_succeeded++;
|
|
break;
|
|
}
|
|
break;
|
|
default:
|
|
/*
|
|
* Permanent failure (-EBUSY, etc.):
|
|
* unlike -EAGAIN case, the failed page is
|
|
* removed from migration page list and not
|
|
* retried in the next outer loop.
|
|
*/
|
|
if (is_thp) {
|
|
nr_thp_failed++;
|
|
nr_failed_pages += nr_subpages;
|
|
break;
|
|
}
|
|
|
|
if (!no_subpage_counting)
|
|
nr_failed++;
|
|
nr_failed_pages += nr_subpages;
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
nr_failed += retry;
|
|
nr_thp_failed += thp_retry;
|
|
/*
|
|
* Try to migrate subpages of fail-to-migrate THPs, no nr_failed
|
|
* counting in this round, since all subpages of a THP is counted
|
|
* as 1 failure in the first round.
|
|
*/
|
|
if (!list_empty(&thp_split_pages)) {
|
|
/*
|
|
* Move non-migrated pages (after 10 retries) to ret_pages
|
|
* to avoid migrating them again.
|
|
*/
|
|
list_splice_init(from, &ret_pages);
|
|
list_splice_init(&thp_split_pages, from);
|
|
no_subpage_counting = true;
|
|
retry = 1;
|
|
goto thp_subpage_migration;
|
|
}
|
|
|
|
rc = nr_failed + nr_thp_failed;
|
|
out:
|
|
/*
|
|
* Put the permanent failure page back to migration list, they
|
|
* will be put back to the right list by the caller.
|
|
*/
|
|
list_splice(&ret_pages, from);
|
|
|
|
count_vm_events(PGMIGRATE_SUCCESS, nr_succeeded);
|
|
count_vm_events(PGMIGRATE_FAIL, nr_failed_pages);
|
|
count_vm_events(THP_MIGRATION_SUCCESS, nr_thp_succeeded);
|
|
count_vm_events(THP_MIGRATION_FAIL, nr_thp_failed);
|
|
count_vm_events(THP_MIGRATION_SPLIT, nr_thp_split);
|
|
trace_mm_migrate_pages(nr_succeeded, nr_failed_pages, nr_thp_succeeded,
|
|
nr_thp_failed, nr_thp_split, mode, reason);
|
|
|
|
if (!swapwrite)
|
|
current->flags &= ~PF_SWAPWRITE;
|
|
|
|
if (ret_succeeded)
|
|
*ret_succeeded = nr_succeeded;
|
|
|
|
return rc;
|
|
}
|
|
|
|
struct page *alloc_migration_target(struct page *page, unsigned long private)
|
|
{
|
|
struct migration_target_control *mtc;
|
|
gfp_t gfp_mask;
|
|
unsigned int order = 0;
|
|
struct page *new_page = NULL;
|
|
int nid;
|
|
int zidx;
|
|
|
|
mtc = (struct migration_target_control *)private;
|
|
gfp_mask = mtc->gfp_mask;
|
|
nid = mtc->nid;
|
|
if (nid == NUMA_NO_NODE)
|
|
nid = page_to_nid(page);
|
|
|
|
if (PageHuge(page)) {
|
|
struct hstate *h = page_hstate(compound_head(page));
|
|
|
|
gfp_mask = htlb_modify_alloc_mask(h, gfp_mask);
|
|
return alloc_huge_page_nodemask(h, nid, mtc->nmask, gfp_mask);
|
|
}
|
|
|
|
if (PageTransHuge(page)) {
|
|
/*
|
|
* clear __GFP_RECLAIM to make the migration callback
|
|
* consistent with regular THP allocations.
|
|
*/
|
|
gfp_mask &= ~__GFP_RECLAIM;
|
|
gfp_mask |= GFP_TRANSHUGE;
|
|
order = HPAGE_PMD_ORDER;
|
|
}
|
|
zidx = zone_idx(page_zone(page));
|
|
if (is_highmem_idx(zidx) || zidx == ZONE_MOVABLE)
|
|
gfp_mask |= __GFP_HIGHMEM;
|
|
|
|
new_page = __alloc_pages(gfp_mask, order, nid, mtc->nmask);
|
|
|
|
if (new_page && PageTransHuge(new_page))
|
|
prep_transhuge_page(new_page);
|
|
|
|
return new_page;
|
|
}
|
|
|
|
#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 mm_struct *mm,
|
|
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, unsigned long addr,
|
|
int node, struct list_head *pagelist, bool migrate_all)
|
|
{
|
|
struct vm_area_struct *vma;
|
|
struct page *page;
|
|
unsigned int follflags;
|
|
int err;
|
|
|
|
mmap_read_lock(mm);
|
|
err = -EFAULT;
|
|
vma = find_vma(mm, addr);
|
|
if (!vma || addr < vma->vm_start || !vma_migratable(vma))
|
|
goto out;
|
|
|
|
/* FOLL_DUMP to ignore special (like zero) pages */
|
|
follflags = FOLL_GET | FOLL_DUMP;
|
|
page = follow_page(vma, addr, follflags);
|
|
|
|
err = PTR_ERR(page);
|
|
if (IS_ERR(page))
|
|
goto out;
|
|
|
|
err = -ENOENT;
|
|
if (!page)
|
|
goto out;
|
|
|
|
err = 0;
|
|
if (page_to_nid(page) == node)
|
|
goto out_putpage;
|
|
|
|
err = -EACCES;
|
|
if (page_mapcount(page) > 1 && !migrate_all)
|
|
goto out_putpage;
|
|
|
|
if (PageHuge(page)) {
|
|
if (PageHead(page)) {
|
|
isolate_huge_page(page, pagelist);
|
|
err = 1;
|
|
}
|
|
} else {
|
|
struct page *head;
|
|
|
|
head = compound_head(page);
|
|
err = isolate_lru_page(head);
|
|
if (err)
|
|
goto out_putpage;
|
|
|
|
err = 1;
|
|
list_add_tail(&head->lru, pagelist);
|
|
mod_node_page_state(page_pgdat(head),
|
|
NR_ISOLATED_ANON + page_is_file_lru(head),
|
|
thp_nr_pages(head));
|
|
}
|
|
out_putpage:
|
|
/*
|
|
* Either remove the duplicate refcount from
|
|
* isolate_lru_page() or drop the page ref if it was
|
|
* not isolated.
|
|
*/
|
|
put_page(page);
|
|
out:
|
|
mmap_read_unlock(mm);
|
|
return err;
|
|
}
|
|
|
|
static int move_pages_and_store_status(struct mm_struct *mm, 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(mm, 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 - 1;
|
|
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)
|
|
{
|
|
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;
|
|
unsigned long addr;
|
|
int node;
|
|
|
|
err = -EFAULT;
|
|
if (get_user(p, pages + i))
|
|
goto out_flush;
|
|
if (get_user(node, nodes + i))
|
|
goto out_flush;
|
|
addr = (unsigned long)untagged_addr(p);
|
|
|
|
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(mm, 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, addr, current_node,
|
|
&pagelist, flags & MPOL_MF_MOVE_ALL);
|
|
|
|
if (err > 0) {
|
|
/* The page is successfully queued for migration */
|
|
continue;
|
|
}
|
|
|
|
/*
|
|
* 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(mm, current_node, &pagelist,
|
|
status, start, i, nr_pages);
|
|
if (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(mm, 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_DUMP);
|
|
|
|
err = PTR_ERR(page);
|
|
if (IS_ERR(page))
|
|
goto set_status;
|
|
|
|
err = page ? page_to_nid(page) : -ENOENT;
|
|
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 16
|
|
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;
|
|
|
|
chunk_nr = nr_pages;
|
|
if (chunk_nr > DO_PAGES_STAT_CHUNK_NR)
|
|
chunk_nr = 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 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 (!populated_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 page *alloc_misplaced_dst_page(struct page *page,
|
|
unsigned long data)
|
|
{
|
|
int nid = (int) data;
|
|
struct page *newpage;
|
|
|
|
newpage = __alloc_pages_node(nid,
|
|
(GFP_HIGHUSER_MOVABLE |
|
|
__GFP_THISNODE | __GFP_NOMEMALLOC |
|
|
__GFP_NORETRY | __GFP_NOWARN) &
|
|
~__GFP_RECLAIM, 0);
|
|
|
|
return newpage;
|
|
}
|
|
|
|
static struct page *alloc_misplaced_dst_page_thp(struct page *page,
|
|
unsigned long data)
|
|
{
|
|
int nid = (int) data;
|
|
struct page *newpage;
|
|
|
|
newpage = alloc_pages_node(nid, (GFP_TRANSHUGE_LIGHT | __GFP_THISNODE),
|
|
HPAGE_PMD_ORDER);
|
|
if (!newpage)
|
|
goto out;
|
|
|
|
prep_transhuge_page(newpage);
|
|
|
|
out:
|
|
return newpage;
|
|
}
|
|
|
|
static int numamigrate_isolate_page(pg_data_t *pgdat, struct page *page)
|
|
{
|
|
int page_lru;
|
|
int nr_pages = thp_nr_pages(page);
|
|
|
|
VM_BUG_ON_PAGE(compound_order(page) && !PageTransHuge(page), page);
|
|
|
|
/* Do not migrate THP mapped by multiple processes */
|
|
if (PageTransHuge(page) && total_mapcount(page) > 1)
|
|
return 0;
|
|
|
|
/* Avoid migrating to a node that is nearly full */
|
|
if (!migrate_balanced_pgdat(pgdat, nr_pages))
|
|
return 0;
|
|
|
|
if (isolate_lru_page(page))
|
|
return 0;
|
|
|
|
page_lru = page_is_file_lru(page);
|
|
mod_node_page_state(page_pgdat(page), NR_ISOLATED_ANON + page_lru,
|
|
nr_pages);
|
|
|
|
/*
|
|
* Isolating the page has taken another reference, so the
|
|
* caller's reference can be safely dropped without the page
|
|
* disappearing underneath us during migration.
|
|
*/
|
|
put_page(page);
|
|
return 1;
|
|
}
|
|
|
|
/*
|
|
* Attempt to migrate a misplaced page to the specified destination
|
|
* node. Caller is expected to have an elevated reference count on
|
|
* the page that will be dropped by this function before returning.
|
|
*/
|
|
int migrate_misplaced_page(struct page *page, struct vm_area_struct *vma,
|
|
int node)
|
|
{
|
|
pg_data_t *pgdat = NODE_DATA(node);
|
|
int isolated;
|
|
int nr_remaining;
|
|
LIST_HEAD(migratepages);
|
|
new_page_t *new;
|
|
bool compound;
|
|
int nr_pages = thp_nr_pages(page);
|
|
|
|
/*
|
|
* PTE mapped THP or HugeTLB page can't reach here so the page could
|
|
* be either base page or THP. And it must be head page if it is
|
|
* THP.
|
|
*/
|
|
compound = PageTransHuge(page);
|
|
|
|
if (compound)
|
|
new = alloc_misplaced_dst_page_thp;
|
|
else
|
|
new = alloc_misplaced_dst_page;
|
|
|
|
/*
|
|
* Don't migrate file pages that are mapped in multiple processes
|
|
* with execute permissions as they are probably shared libraries.
|
|
*/
|
|
if (page_mapcount(page) != 1 && page_is_file_lru(page) &&
|
|
(vma->vm_flags & VM_EXEC))
|
|
goto out;
|
|
|
|
/*
|
|
* Also do not migrate dirty pages as not all filesystems can move
|
|
* dirty pages in MIGRATE_ASYNC mode which is a waste of cycles.
|
|
*/
|
|
if (page_is_file_lru(page) && PageDirty(page))
|
|
goto out;
|
|
|
|
isolated = numamigrate_isolate_page(pgdat, page);
|
|
if (!isolated)
|
|
goto out;
|
|
|
|
list_add(&page->lru, &migratepages);
|
|
nr_remaining = migrate_pages(&migratepages, *new, NULL, node,
|
|
MIGRATE_ASYNC, MR_NUMA_MISPLACED, NULL);
|
|
if (nr_remaining) {
|
|
if (!list_empty(&migratepages)) {
|
|
list_del(&page->lru);
|
|
mod_node_page_state(page_pgdat(page), NR_ISOLATED_ANON +
|
|
page_is_file_lru(page), -nr_pages);
|
|
putback_lru_page(page);
|
|
}
|
|
isolated = 0;
|
|
} else
|
|
count_vm_numa_events(NUMA_PAGE_MIGRATE, nr_pages);
|
|
BUG_ON(!list_empty(&migratepages));
|
|
return isolated;
|
|
|
|
out:
|
|
put_page(page);
|
|
return 0;
|
|
}
|
|
#endif /* CONFIG_NUMA_BALANCING */
|
|
#endif /* CONFIG_NUMA */
|
|
|
|
#ifdef CONFIG_DEVICE_PRIVATE
|
|
static int migrate_vma_collect_skip(unsigned long start,
|
|
unsigned long end,
|
|
struct mm_walk *walk)
|
|
{
|
|
struct migrate_vma *migrate = walk->private;
|
|
unsigned long addr;
|
|
|
|
for (addr = start; addr < end; addr += PAGE_SIZE) {
|
|
migrate->dst[migrate->npages] = 0;
|
|
migrate->src[migrate->npages++] = 0;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int migrate_vma_collect_hole(unsigned long start,
|
|
unsigned long end,
|
|
__always_unused int depth,
|
|
struct mm_walk *walk)
|
|
{
|
|
struct migrate_vma *migrate = walk->private;
|
|
unsigned long addr;
|
|
|
|
/* Only allow populating anonymous memory. */
|
|
if (!vma_is_anonymous(walk->vma))
|
|
return migrate_vma_collect_skip(start, end, walk);
|
|
|
|
for (addr = start; addr < end; addr += PAGE_SIZE) {
|
|
migrate->src[migrate->npages] = MIGRATE_PFN_MIGRATE;
|
|
migrate->dst[migrate->npages] = 0;
|
|
migrate->npages++;
|
|
migrate->cpages++;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int migrate_vma_collect_pmd(pmd_t *pmdp,
|
|
unsigned long start,
|
|
unsigned long end,
|
|
struct mm_walk *walk)
|
|
{
|
|
struct migrate_vma *migrate = walk->private;
|
|
struct vm_area_struct *vma = walk->vma;
|
|
struct mm_struct *mm = vma->vm_mm;
|
|
unsigned long addr = start, unmapped = 0;
|
|
spinlock_t *ptl;
|
|
pte_t *ptep;
|
|
|
|
again:
|
|
if (pmd_none(*pmdp))
|
|
return migrate_vma_collect_hole(start, end, -1, walk);
|
|
|
|
if (pmd_trans_huge(*pmdp)) {
|
|
struct page *page;
|
|
|
|
ptl = pmd_lock(mm, pmdp);
|
|
if (unlikely(!pmd_trans_huge(*pmdp))) {
|
|
spin_unlock(ptl);
|
|
goto again;
|
|
}
|
|
|
|
page = pmd_page(*pmdp);
|
|
if (is_huge_zero_page(page)) {
|
|
spin_unlock(ptl);
|
|
split_huge_pmd(vma, pmdp, addr);
|
|
if (pmd_trans_unstable(pmdp))
|
|
return migrate_vma_collect_skip(start, end,
|
|
walk);
|
|
} else {
|
|
int ret;
|
|
|
|
get_page(page);
|
|
spin_unlock(ptl);
|
|
if (unlikely(!trylock_page(page)))
|
|
return migrate_vma_collect_skip(start, end,
|
|
walk);
|
|
ret = split_huge_page(page);
|
|
unlock_page(page);
|
|
put_page(page);
|
|
if (ret)
|
|
return migrate_vma_collect_skip(start, end,
|
|
walk);
|
|
if (pmd_none(*pmdp))
|
|
return migrate_vma_collect_hole(start, end, -1,
|
|
walk);
|
|
}
|
|
}
|
|
|
|
if (unlikely(pmd_bad(*pmdp)))
|
|
return migrate_vma_collect_skip(start, end, walk);
|
|
|
|
ptep = pte_offset_map_lock(mm, pmdp, addr, &ptl);
|
|
arch_enter_lazy_mmu_mode();
|
|
|
|
for (; addr < end; addr += PAGE_SIZE, ptep++) {
|
|
unsigned long mpfn = 0, pfn;
|
|
struct page *page;
|
|
swp_entry_t entry;
|
|
pte_t pte;
|
|
|
|
pte = *ptep;
|
|
|
|
if (pte_none(pte)) {
|
|
if (vma_is_anonymous(vma)) {
|
|
mpfn = MIGRATE_PFN_MIGRATE;
|
|
migrate->cpages++;
|
|
}
|
|
goto next;
|
|
}
|
|
|
|
if (!pte_present(pte)) {
|
|
/*
|
|
* Only care about unaddressable device page special
|
|
* page table entry. Other special swap entries are not
|
|
* migratable, and we ignore regular swapped page.
|
|
*/
|
|
entry = pte_to_swp_entry(pte);
|
|
if (!is_device_private_entry(entry))
|
|
goto next;
|
|
|
|
page = pfn_swap_entry_to_page(entry);
|
|
if (!(migrate->flags &
|
|
MIGRATE_VMA_SELECT_DEVICE_PRIVATE) ||
|
|
page->pgmap->owner != migrate->pgmap_owner)
|
|
goto next;
|
|
|
|
mpfn = migrate_pfn(page_to_pfn(page)) |
|
|
MIGRATE_PFN_MIGRATE;
|
|
if (is_writable_device_private_entry(entry))
|
|
mpfn |= MIGRATE_PFN_WRITE;
|
|
} else {
|
|
if (!(migrate->flags & MIGRATE_VMA_SELECT_SYSTEM))
|
|
goto next;
|
|
pfn = pte_pfn(pte);
|
|
if (is_zero_pfn(pfn)) {
|
|
mpfn = MIGRATE_PFN_MIGRATE;
|
|
migrate->cpages++;
|
|
goto next;
|
|
}
|
|
page = vm_normal_page(migrate->vma, addr, pte);
|
|
mpfn = migrate_pfn(pfn) | MIGRATE_PFN_MIGRATE;
|
|
mpfn |= pte_write(pte) ? MIGRATE_PFN_WRITE : 0;
|
|
}
|
|
|
|
/* FIXME support THP */
|
|
if (!page || !page->mapping || PageTransCompound(page)) {
|
|
mpfn = 0;
|
|
goto next;
|
|
}
|
|
|
|
/*
|
|
* By getting a reference on the page we pin it and that blocks
|
|
* any kind of migration. Side effect is that it "freezes" the
|
|
* pte.
|
|
*
|
|
* We drop this reference after isolating the page from the lru
|
|
* for non device page (device page are not on the lru and thus
|
|
* can't be dropped from it).
|
|
*/
|
|
get_page(page);
|
|
|
|
/*
|
|
* Optimize for the common case where page is only mapped once
|
|
* in one process. If we can lock the page, then we can safely
|
|
* set up a special migration page table entry now.
|
|
*/
|
|
if (trylock_page(page)) {
|
|
pte_t swp_pte;
|
|
|
|
migrate->cpages++;
|
|
ptep_get_and_clear(mm, addr, ptep);
|
|
|
|
/* Setup special migration page table entry */
|
|
if (mpfn & MIGRATE_PFN_WRITE)
|
|
entry = make_writable_migration_entry(
|
|
page_to_pfn(page));
|
|
else
|
|
entry = make_readable_migration_entry(
|
|
page_to_pfn(page));
|
|
swp_pte = swp_entry_to_pte(entry);
|
|
if (pte_present(pte)) {
|
|
if (pte_soft_dirty(pte))
|
|
swp_pte = pte_swp_mksoft_dirty(swp_pte);
|
|
if (pte_uffd_wp(pte))
|
|
swp_pte = pte_swp_mkuffd_wp(swp_pte);
|
|
} else {
|
|
if (pte_swp_soft_dirty(pte))
|
|
swp_pte = pte_swp_mksoft_dirty(swp_pte);
|
|
if (pte_swp_uffd_wp(pte))
|
|
swp_pte = pte_swp_mkuffd_wp(swp_pte);
|
|
}
|
|
set_pte_at(mm, addr, ptep, swp_pte);
|
|
|
|
/*
|
|
* This is like regular unmap: we remove the rmap and
|
|
* drop page refcount. Page won't be freed, as we took
|
|
* a reference just above.
|
|
*/
|
|
page_remove_rmap(page, false);
|
|
put_page(page);
|
|
|
|
if (pte_present(pte))
|
|
unmapped++;
|
|
} else {
|
|
put_page(page);
|
|
mpfn = 0;
|
|
}
|
|
|
|
next:
|
|
migrate->dst[migrate->npages] = 0;
|
|
migrate->src[migrate->npages++] = mpfn;
|
|
}
|
|
arch_leave_lazy_mmu_mode();
|
|
pte_unmap_unlock(ptep - 1, ptl);
|
|
|
|
/* Only flush the TLB if we actually modified any entries */
|
|
if (unmapped)
|
|
flush_tlb_range(walk->vma, start, end);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static const struct mm_walk_ops migrate_vma_walk_ops = {
|
|
.pmd_entry = migrate_vma_collect_pmd,
|
|
.pte_hole = migrate_vma_collect_hole,
|
|
};
|
|
|
|
/*
|
|
* migrate_vma_collect() - collect pages over a range of virtual addresses
|
|
* @migrate: migrate struct containing all migration information
|
|
*
|
|
* This will walk the CPU page table. For each virtual address backed by a
|
|
* valid page, it updates the src array and takes a reference on the page, in
|
|
* order to pin the page until we lock it and unmap it.
|
|
*/
|
|
static void migrate_vma_collect(struct migrate_vma *migrate)
|
|
{
|
|
struct mmu_notifier_range range;
|
|
|
|
/*
|
|
* Note that the pgmap_owner is passed to the mmu notifier callback so
|
|
* that the registered device driver can skip invalidating device
|
|
* private page mappings that won't be migrated.
|
|
*/
|
|
mmu_notifier_range_init_owner(&range, MMU_NOTIFY_MIGRATE, 0,
|
|
migrate->vma, migrate->vma->vm_mm, migrate->start, migrate->end,
|
|
migrate->pgmap_owner);
|
|
mmu_notifier_invalidate_range_start(&range);
|
|
|
|
walk_page_range(migrate->vma->vm_mm, migrate->start, migrate->end,
|
|
&migrate_vma_walk_ops, migrate);
|
|
|
|
mmu_notifier_invalidate_range_end(&range);
|
|
migrate->end = migrate->start + (migrate->npages << PAGE_SHIFT);
|
|
}
|
|
|
|
/*
|
|
* migrate_vma_check_page() - check if page is pinned or not
|
|
* @page: struct page to check
|
|
*
|
|
* Pinned pages cannot be migrated. This is the same test as in
|
|
* folio_migrate_mapping(), except that here we allow migration of a
|
|
* ZONE_DEVICE page.
|
|
*/
|
|
static bool migrate_vma_check_page(struct page *page)
|
|
{
|
|
/*
|
|
* One extra ref because caller holds an extra reference, either from
|
|
* isolate_lru_page() for a regular page, or migrate_vma_collect() for
|
|
* a device page.
|
|
*/
|
|
int extra = 1;
|
|
|
|
/*
|
|
* FIXME support THP (transparent huge page), it is bit more complex to
|
|
* check them than regular pages, because they can be mapped with a pmd
|
|
* or with a pte (split pte mapping).
|
|
*/
|
|
if (PageCompound(page))
|
|
return false;
|
|
|
|
/* Page from ZONE_DEVICE have one extra reference */
|
|
if (is_zone_device_page(page))
|
|
extra++;
|
|
|
|
/* For file back page */
|
|
if (page_mapping(page))
|
|
extra += 1 + page_has_private(page);
|
|
|
|
if ((page_count(page) - extra) > page_mapcount(page))
|
|
return false;
|
|
|
|
return true;
|
|
}
|
|
|
|
/*
|
|
* migrate_vma_unmap() - replace page mapping with special migration pte entry
|
|
* @migrate: migrate struct containing all migration information
|
|
*
|
|
* Isolate pages from the LRU and replace mappings (CPU page table pte) with a
|
|
* special migration pte entry and check if it has been pinned. Pinned pages are
|
|
* restored because we cannot migrate them.
|
|
*
|
|
* This is the last step before we call the device driver callback to allocate
|
|
* destination memory and copy contents of original page over to new page.
|
|
*/
|
|
static void migrate_vma_unmap(struct migrate_vma *migrate)
|
|
{
|
|
const unsigned long npages = migrate->npages;
|
|
unsigned long i, restore = 0;
|
|
bool allow_drain = true;
|
|
|
|
lru_add_drain();
|
|
|
|
for (i = 0; i < npages; i++) {
|
|
struct page *page = migrate_pfn_to_page(migrate->src[i]);
|
|
|
|
if (!page)
|
|
continue;
|
|
|
|
/* ZONE_DEVICE pages are not on LRU */
|
|
if (!is_zone_device_page(page)) {
|
|
if (!PageLRU(page) && allow_drain) {
|
|
/* Drain CPU's pagevec */
|
|
lru_add_drain_all();
|
|
allow_drain = false;
|
|
}
|
|
|
|
if (isolate_lru_page(page)) {
|
|
migrate->src[i] &= ~MIGRATE_PFN_MIGRATE;
|
|
migrate->cpages--;
|
|
restore++;
|
|
continue;
|
|
}
|
|
|
|
/* Drop the reference we took in collect */
|
|
put_page(page);
|
|
}
|
|
|
|
if (page_mapped(page))
|
|
try_to_migrate(page, 0);
|
|
|
|
if (page_mapped(page) || !migrate_vma_check_page(page)) {
|
|
if (!is_zone_device_page(page)) {
|
|
get_page(page);
|
|
putback_lru_page(page);
|
|
}
|
|
|
|
migrate->src[i] &= ~MIGRATE_PFN_MIGRATE;
|
|
migrate->cpages--;
|
|
restore++;
|
|
continue;
|
|
}
|
|
}
|
|
|
|
for (i = 0; i < npages && restore; i++) {
|
|
struct page *page = migrate_pfn_to_page(migrate->src[i]);
|
|
|
|
if (!page || (migrate->src[i] & MIGRATE_PFN_MIGRATE))
|
|
continue;
|
|
|
|
remove_migration_ptes(page, page, false);
|
|
|
|
migrate->src[i] = 0;
|
|
unlock_page(page);
|
|
put_page(page);
|
|
restore--;
|
|
}
|
|
}
|
|
|
|
/**
|
|
* migrate_vma_setup() - prepare to migrate a range of memory
|
|
* @args: contains the vma, start, and pfns arrays for the migration
|
|
*
|
|
* Returns: negative errno on failures, 0 when 0 or more pages were migrated
|
|
* without an error.
|
|
*
|
|
* Prepare to migrate a range of memory virtual address range by collecting all
|
|
* the pages backing each virtual address in the range, saving them inside the
|
|
* src array. Then lock those pages and unmap them. Once the pages are locked
|
|
* and unmapped, check whether each page is pinned or not. Pages that aren't
|
|
* pinned have the MIGRATE_PFN_MIGRATE flag set (by this function) in the
|
|
* corresponding src array entry. Then restores any pages that are pinned, by
|
|
* remapping and unlocking those pages.
|
|
*
|
|
* The caller should then allocate destination memory and copy source memory to
|
|
* it for all those entries (ie with MIGRATE_PFN_VALID and MIGRATE_PFN_MIGRATE
|
|
* flag set). Once these are allocated and copied, the caller must update each
|
|
* corresponding entry in the dst array with the pfn value of the destination
|
|
* page and with MIGRATE_PFN_VALID. Destination pages must be locked via
|
|
* lock_page().
|
|
*
|
|
* Note that the caller does not have to migrate all the pages that are marked
|
|
* with MIGRATE_PFN_MIGRATE flag in src array unless this is a migration from
|
|
* device memory to system memory. If the caller cannot migrate a device page
|
|
* back to system memory, then it must return VM_FAULT_SIGBUS, which has severe
|
|
* consequences for the userspace process, so it must be avoided if at all
|
|
* possible.
|
|
*
|
|
* For empty entries inside CPU page table (pte_none() or pmd_none() is true) we
|
|
* do set MIGRATE_PFN_MIGRATE flag inside the corresponding source array thus
|
|
* allowing the caller to allocate device memory for those unbacked virtual
|
|
* addresses. For this the caller simply has to allocate device memory and
|
|
* properly set the destination entry like for regular migration. Note that
|
|
* this can still fail, and thus inside the device driver you must check if the
|
|
* migration was successful for those entries after calling migrate_vma_pages(),
|
|
* just like for regular migration.
|
|
*
|
|
* After that, the callers must call migrate_vma_pages() to go over each entry
|
|
* in the src array that has the MIGRATE_PFN_VALID and MIGRATE_PFN_MIGRATE flag
|
|
* set. If the corresponding entry in dst array has MIGRATE_PFN_VALID flag set,
|
|
* then migrate_vma_pages() to migrate struct page information from the source
|
|
* struct page to the destination struct page. If it fails to migrate the
|
|
* struct page information, then it clears the MIGRATE_PFN_MIGRATE flag in the
|
|
* src array.
|
|
*
|
|
* At this point all successfully migrated pages have an entry in the src
|
|
* array with MIGRATE_PFN_VALID and MIGRATE_PFN_MIGRATE flag set and the dst
|
|
* array entry with MIGRATE_PFN_VALID flag set.
|
|
*
|
|
* Once migrate_vma_pages() returns the caller may inspect which pages were
|
|
* successfully migrated, and which were not. Successfully migrated pages will
|
|
* have the MIGRATE_PFN_MIGRATE flag set for their src array entry.
|
|
*
|
|
* It is safe to update device page table after migrate_vma_pages() because
|
|
* both destination and source page are still locked, and the mmap_lock is held
|
|
* in read mode (hence no one can unmap the range being migrated).
|
|
*
|
|
* Once the caller is done cleaning up things and updating its page table (if it
|
|
* chose to do so, this is not an obligation) it finally calls
|
|
* migrate_vma_finalize() to update the CPU page table to point to new pages
|
|
* for successfully migrated pages or otherwise restore the CPU page table to
|
|
* point to the original source pages.
|
|
*/
|
|
int migrate_vma_setup(struct migrate_vma *args)
|
|
{
|
|
long nr_pages = (args->end - args->start) >> PAGE_SHIFT;
|
|
|
|
args->start &= PAGE_MASK;
|
|
args->end &= PAGE_MASK;
|
|
if (!args->vma || is_vm_hugetlb_page(args->vma) ||
|
|
(args->vma->vm_flags & VM_SPECIAL) || vma_is_dax(args->vma))
|
|
return -EINVAL;
|
|
if (nr_pages <= 0)
|
|
return -EINVAL;
|
|
if (args->start < args->vma->vm_start ||
|
|
args->start >= args->vma->vm_end)
|
|
return -EINVAL;
|
|
if (args->end <= args->vma->vm_start || args->end > args->vma->vm_end)
|
|
return -EINVAL;
|
|
if (!args->src || !args->dst)
|
|
return -EINVAL;
|
|
|
|
memset(args->src, 0, sizeof(*args->src) * nr_pages);
|
|
args->cpages = 0;
|
|
args->npages = 0;
|
|
|
|
migrate_vma_collect(args);
|
|
|
|
if (args->cpages)
|
|
migrate_vma_unmap(args);
|
|
|
|
/*
|
|
* At this point pages are locked and unmapped, and thus they have
|
|
* stable content and can safely be copied to destination memory that
|
|
* is allocated by the drivers.
|
|
*/
|
|
return 0;
|
|
|
|
}
|
|
EXPORT_SYMBOL(migrate_vma_setup);
|
|
|
|
/*
|
|
* This code closely matches the code in:
|
|
* __handle_mm_fault()
|
|
* handle_pte_fault()
|
|
* do_anonymous_page()
|
|
* to map in an anonymous zero page but the struct page will be a ZONE_DEVICE
|
|
* private page.
|
|
*/
|
|
static void migrate_vma_insert_page(struct migrate_vma *migrate,
|
|
unsigned long addr,
|
|
struct page *page,
|
|
unsigned long *src)
|
|
{
|
|
struct vm_area_struct *vma = migrate->vma;
|
|
struct mm_struct *mm = vma->vm_mm;
|
|
bool flush = false;
|
|
spinlock_t *ptl;
|
|
pte_t entry;
|
|
pgd_t *pgdp;
|
|
p4d_t *p4dp;
|
|
pud_t *pudp;
|
|
pmd_t *pmdp;
|
|
pte_t *ptep;
|
|
|
|
/* Only allow populating anonymous memory */
|
|
if (!vma_is_anonymous(vma))
|
|
goto abort;
|
|
|
|
pgdp = pgd_offset(mm, addr);
|
|
p4dp = p4d_alloc(mm, pgdp, addr);
|
|
if (!p4dp)
|
|
goto abort;
|
|
pudp = pud_alloc(mm, p4dp, addr);
|
|
if (!pudp)
|
|
goto abort;
|
|
pmdp = pmd_alloc(mm, pudp, addr);
|
|
if (!pmdp)
|
|
goto abort;
|
|
|
|
if (pmd_trans_huge(*pmdp) || pmd_devmap(*pmdp))
|
|
goto abort;
|
|
|
|
/*
|
|
* Use pte_alloc() instead of pte_alloc_map(). We can't run
|
|
* pte_offset_map() on pmds where a huge pmd might be created
|
|
* from a different thread.
|
|
*
|
|
* pte_alloc_map() is safe to use under mmap_write_lock(mm) or when
|
|
* parallel threads are excluded by other means.
|
|
*
|
|
* Here we only have mmap_read_lock(mm).
|
|
*/
|
|
if (pte_alloc(mm, pmdp))
|
|
goto abort;
|
|
|
|
/* See the comment in pte_alloc_one_map() */
|
|
if (unlikely(pmd_trans_unstable(pmdp)))
|
|
goto abort;
|
|
|
|
if (unlikely(anon_vma_prepare(vma)))
|
|
goto abort;
|
|
if (mem_cgroup_charge(page_folio(page), vma->vm_mm, GFP_KERNEL))
|
|
goto abort;
|
|
|
|
/*
|
|
* The memory barrier inside __SetPageUptodate makes sure that
|
|
* preceding stores to the page contents become visible before
|
|
* the set_pte_at() write.
|
|
*/
|
|
__SetPageUptodate(page);
|
|
|
|
if (is_zone_device_page(page)) {
|
|
if (is_device_private_page(page)) {
|
|
swp_entry_t swp_entry;
|
|
|
|
if (vma->vm_flags & VM_WRITE)
|
|
swp_entry = make_writable_device_private_entry(
|
|
page_to_pfn(page));
|
|
else
|
|
swp_entry = make_readable_device_private_entry(
|
|
page_to_pfn(page));
|
|
entry = swp_entry_to_pte(swp_entry);
|
|
} else {
|
|
/*
|
|
* For now we only support migrating to un-addressable
|
|
* device memory.
|
|
*/
|
|
pr_warn_once("Unsupported ZONE_DEVICE page type.\n");
|
|
goto abort;
|
|
}
|
|
} else {
|
|
entry = mk_pte(page, vma->vm_page_prot);
|
|
if (vma->vm_flags & VM_WRITE)
|
|
entry = pte_mkwrite(pte_mkdirty(entry));
|
|
}
|
|
|
|
ptep = pte_offset_map_lock(mm, pmdp, addr, &ptl);
|
|
|
|
if (check_stable_address_space(mm))
|
|
goto unlock_abort;
|
|
|
|
if (pte_present(*ptep)) {
|
|
unsigned long pfn = pte_pfn(*ptep);
|
|
|
|
if (!is_zero_pfn(pfn))
|
|
goto unlock_abort;
|
|
flush = true;
|
|
} else if (!pte_none(*ptep))
|
|
goto unlock_abort;
|
|
|
|
/*
|
|
* Check for userfaultfd but do not deliver the fault. Instead,
|
|
* just back off.
|
|
*/
|
|
if (userfaultfd_missing(vma))
|
|
goto unlock_abort;
|
|
|
|
inc_mm_counter(mm, MM_ANONPAGES);
|
|
page_add_new_anon_rmap(page, vma, addr, false);
|
|
if (!is_zone_device_page(page))
|
|
lru_cache_add_inactive_or_unevictable(page, vma);
|
|
get_page(page);
|
|
|
|
if (flush) {
|
|
flush_cache_page(vma, addr, pte_pfn(*ptep));
|
|
ptep_clear_flush_notify(vma, addr, ptep);
|
|
set_pte_at_notify(mm, addr, ptep, entry);
|
|
update_mmu_cache(vma, addr, ptep);
|
|
} else {
|
|
/* No need to invalidate - it was non-present before */
|
|
set_pte_at(mm, addr, ptep, entry);
|
|
update_mmu_cache(vma, addr, ptep);
|
|
}
|
|
|
|
pte_unmap_unlock(ptep, ptl);
|
|
*src = MIGRATE_PFN_MIGRATE;
|
|
return;
|
|
|
|
unlock_abort:
|
|
pte_unmap_unlock(ptep, ptl);
|
|
abort:
|
|
*src &= ~MIGRATE_PFN_MIGRATE;
|
|
}
|
|
|
|
/**
|
|
* migrate_vma_pages() - migrate meta-data from src page to dst page
|
|
* @migrate: migrate struct containing all migration information
|
|
*
|
|
* This migrates struct page meta-data from source struct page to destination
|
|
* struct page. This effectively finishes the migration from source page to the
|
|
* destination page.
|
|
*/
|
|
void migrate_vma_pages(struct migrate_vma *migrate)
|
|
{
|
|
const unsigned long npages = migrate->npages;
|
|
const unsigned long start = migrate->start;
|
|
struct mmu_notifier_range range;
|
|
unsigned long addr, i;
|
|
bool notified = false;
|
|
|
|
for (i = 0, addr = start; i < npages; addr += PAGE_SIZE, i++) {
|
|
struct page *newpage = migrate_pfn_to_page(migrate->dst[i]);
|
|
struct page *page = migrate_pfn_to_page(migrate->src[i]);
|
|
struct address_space *mapping;
|
|
int r;
|
|
|
|
if (!newpage) {
|
|
migrate->src[i] &= ~MIGRATE_PFN_MIGRATE;
|
|
continue;
|
|
}
|
|
|
|
if (!page) {
|
|
if (!(migrate->src[i] & MIGRATE_PFN_MIGRATE))
|
|
continue;
|
|
if (!notified) {
|
|
notified = true;
|
|
|
|
mmu_notifier_range_init_owner(&range,
|
|
MMU_NOTIFY_MIGRATE, 0, migrate->vma,
|
|
migrate->vma->vm_mm, addr, migrate->end,
|
|
migrate->pgmap_owner);
|
|
mmu_notifier_invalidate_range_start(&range);
|
|
}
|
|
migrate_vma_insert_page(migrate, addr, newpage,
|
|
&migrate->src[i]);
|
|
continue;
|
|
}
|
|
|
|
mapping = page_mapping(page);
|
|
|
|
if (is_zone_device_page(newpage)) {
|
|
if (is_device_private_page(newpage)) {
|
|
/*
|
|
* For now only support private anonymous when
|
|
* migrating to un-addressable device memory.
|
|
*/
|
|
if (mapping) {
|
|
migrate->src[i] &= ~MIGRATE_PFN_MIGRATE;
|
|
continue;
|
|
}
|
|
} else {
|
|
/*
|
|
* Other types of ZONE_DEVICE page are not
|
|
* supported.
|
|
*/
|
|
migrate->src[i] &= ~MIGRATE_PFN_MIGRATE;
|
|
continue;
|
|
}
|
|
}
|
|
|
|
r = migrate_page(mapping, newpage, page, MIGRATE_SYNC_NO_COPY);
|
|
if (r != MIGRATEPAGE_SUCCESS)
|
|
migrate->src[i] &= ~MIGRATE_PFN_MIGRATE;
|
|
}
|
|
|
|
/*
|
|
* No need to double call mmu_notifier->invalidate_range() callback as
|
|
* the above ptep_clear_flush_notify() inside migrate_vma_insert_page()
|
|
* did already call it.
|
|
*/
|
|
if (notified)
|
|
mmu_notifier_invalidate_range_only_end(&range);
|
|
}
|
|
EXPORT_SYMBOL(migrate_vma_pages);
|
|
|
|
/**
|
|
* migrate_vma_finalize() - restore CPU page table entry
|
|
* @migrate: migrate struct containing all migration information
|
|
*
|
|
* This replaces the special migration pte entry with either a mapping to the
|
|
* new page if migration was successful for that page, or to the original page
|
|
* otherwise.
|
|
*
|
|
* This also unlocks the pages and puts them back on the lru, or drops the extra
|
|
* refcount, for device pages.
|
|
*/
|
|
void migrate_vma_finalize(struct migrate_vma *migrate)
|
|
{
|
|
const unsigned long npages = migrate->npages;
|
|
unsigned long i;
|
|
|
|
for (i = 0; i < npages; i++) {
|
|
struct page *newpage = migrate_pfn_to_page(migrate->dst[i]);
|
|
struct page *page = migrate_pfn_to_page(migrate->src[i]);
|
|
|
|
if (!page) {
|
|
if (newpage) {
|
|
unlock_page(newpage);
|
|
put_page(newpage);
|
|
}
|
|
continue;
|
|
}
|
|
|
|
if (!(migrate->src[i] & MIGRATE_PFN_MIGRATE) || !newpage) {
|
|
if (newpage) {
|
|
unlock_page(newpage);
|
|
put_page(newpage);
|
|
}
|
|
newpage = page;
|
|
}
|
|
|
|
remove_migration_ptes(page, newpage, false);
|
|
unlock_page(page);
|
|
|
|
if (is_zone_device_page(page))
|
|
put_page(page);
|
|
else
|
|
putback_lru_page(page);
|
|
|
|
if (newpage != page) {
|
|
unlock_page(newpage);
|
|
if (is_zone_device_page(newpage))
|
|
put_page(newpage);
|
|
else
|
|
putback_lru_page(newpage);
|
|
}
|
|
}
|
|
}
|
|
EXPORT_SYMBOL(migrate_vma_finalize);
|
|
#endif /* CONFIG_DEVICE_PRIVATE */
|
|
|
|
/*
|
|
* node_demotion[] example:
|
|
*
|
|
* Consider a system with two sockets. Each socket has
|
|
* three classes of memory attached: fast, medium and slow.
|
|
* Each memory class is placed in its own NUMA node. The
|
|
* CPUs are placed in the node with the "fast" memory. The
|
|
* 6 NUMA nodes (0-5) might be split among the sockets like
|
|
* this:
|
|
*
|
|
* Socket A: 0, 1, 2
|
|
* Socket B: 3, 4, 5
|
|
*
|
|
* When Node 0 fills up, its memory should be migrated to
|
|
* Node 1. When Node 1 fills up, it should be migrated to
|
|
* Node 2. The migration path start on the nodes with the
|
|
* processors (since allocations default to this node) and
|
|
* fast memory, progress through medium and end with the
|
|
* slow memory:
|
|
*
|
|
* 0 -> 1 -> 2 -> stop
|
|
* 3 -> 4 -> 5 -> stop
|
|
*
|
|
* This is represented in the node_demotion[] like this:
|
|
*
|
|
* { nr=1, nodes[0]=1 }, // Node 0 migrates to 1
|
|
* { nr=1, nodes[0]=2 }, // Node 1 migrates to 2
|
|
* { nr=0, nodes[0]=-1 }, // Node 2 does not migrate
|
|
* { nr=1, nodes[0]=4 }, // Node 3 migrates to 4
|
|
* { nr=1, nodes[0]=5 }, // Node 4 migrates to 5
|
|
* { nr=0, nodes[0]=-1 }, // Node 5 does not migrate
|
|
*
|
|
* Moreover some systems may have multiple slow memory nodes.
|
|
* Suppose a system has one socket with 3 memory nodes, node 0
|
|
* is fast memory type, and node 1/2 both are slow memory
|
|
* type, and the distance between fast memory node and slow
|
|
* memory node is same. So the migration path should be:
|
|
*
|
|
* 0 -> 1/2 -> stop
|
|
*
|
|
* This is represented in the node_demotion[] like this:
|
|
* { nr=2, {nodes[0]=1, nodes[1]=2} }, // Node 0 migrates to node 1 and node 2
|
|
* { nr=0, nodes[0]=-1, }, // Node 1 dose not migrate
|
|
* { nr=0, nodes[0]=-1, }, // Node 2 does not migrate
|
|
*/
|
|
|
|
/*
|
|
* Writes to this array occur without locking. Cycles are
|
|
* not allowed: Node X demotes to Y which demotes to X...
|
|
*
|
|
* If multiple reads are performed, a single rcu_read_lock()
|
|
* must be held over all reads to ensure that no cycles are
|
|
* observed.
|
|
*/
|
|
#define DEFAULT_DEMOTION_TARGET_NODES 15
|
|
|
|
#if MAX_NUMNODES < DEFAULT_DEMOTION_TARGET_NODES
|
|
#define DEMOTION_TARGET_NODES (MAX_NUMNODES - 1)
|
|
#else
|
|
#define DEMOTION_TARGET_NODES DEFAULT_DEMOTION_TARGET_NODES
|
|
#endif
|
|
|
|
struct demotion_nodes {
|
|
unsigned short nr;
|
|
short nodes[DEMOTION_TARGET_NODES];
|
|
};
|
|
|
|
static struct demotion_nodes *node_demotion __read_mostly;
|
|
|
|
/**
|
|
* next_demotion_node() - Get the next node in the demotion path
|
|
* @node: The starting node to lookup the next node
|
|
*
|
|
* Return: node id for next memory node in the demotion path hierarchy
|
|
* from @node; NUMA_NO_NODE if @node is terminal. This does not keep
|
|
* @node online or guarantee that it *continues* to be the next demotion
|
|
* target.
|
|
*/
|
|
int next_demotion_node(int node)
|
|
{
|
|
struct demotion_nodes *nd;
|
|
unsigned short target_nr, index;
|
|
int target;
|
|
|
|
if (!node_demotion)
|
|
return NUMA_NO_NODE;
|
|
|
|
nd = &node_demotion[node];
|
|
|
|
/*
|
|
* node_demotion[] is updated without excluding this
|
|
* function from running. RCU doesn't provide any
|
|
* compiler barriers, so the READ_ONCE() is required
|
|
* to avoid compiler reordering or read merging.
|
|
*
|
|
* Make sure to use RCU over entire code blocks if
|
|
* node_demotion[] reads need to be consistent.
|
|
*/
|
|
rcu_read_lock();
|
|
target_nr = READ_ONCE(nd->nr);
|
|
|
|
switch (target_nr) {
|
|
case 0:
|
|
target = NUMA_NO_NODE;
|
|
goto out;
|
|
case 1:
|
|
index = 0;
|
|
break;
|
|
default:
|
|
/*
|
|
* If there are multiple target nodes, just select one
|
|
* target node randomly.
|
|
*
|
|
* In addition, we can also use round-robin to select
|
|
* target node, but we should introduce another variable
|
|
* for node_demotion[] to record last selected target node,
|
|
* that may cause cache ping-pong due to the changing of
|
|
* last target node. Or introducing per-cpu data to avoid
|
|
* caching issue, which seems more complicated. So selecting
|
|
* target node randomly seems better until now.
|
|
*/
|
|
index = get_random_int() % target_nr;
|
|
break;
|
|
}
|
|
|
|
target = READ_ONCE(nd->nodes[index]);
|
|
|
|
out:
|
|
rcu_read_unlock();
|
|
return target;
|
|
}
|
|
|
|
#if defined(CONFIG_HOTPLUG_CPU)
|
|
/* Disable reclaim-based migration. */
|
|
static void __disable_all_migrate_targets(void)
|
|
{
|
|
int node, i;
|
|
|
|
if (!node_demotion)
|
|
return;
|
|
|
|
for_each_online_node(node) {
|
|
node_demotion[node].nr = 0;
|
|
for (i = 0; i < DEMOTION_TARGET_NODES; i++)
|
|
node_demotion[node].nodes[i] = NUMA_NO_NODE;
|
|
}
|
|
}
|
|
|
|
static void disable_all_migrate_targets(void)
|
|
{
|
|
__disable_all_migrate_targets();
|
|
|
|
/*
|
|
* Ensure that the "disable" is visible across the system.
|
|
* Readers will see either a combination of before+disable
|
|
* state or disable+after. They will never see before and
|
|
* after state together.
|
|
*
|
|
* The before+after state together might have cycles and
|
|
* could cause readers to do things like loop until this
|
|
* function finishes. This ensures they can only see a
|
|
* single "bad" read and would, for instance, only loop
|
|
* once.
|
|
*/
|
|
synchronize_rcu();
|
|
}
|
|
|
|
/*
|
|
* Find an automatic demotion target for 'node'.
|
|
* Failing here is OK. It might just indicate
|
|
* being at the end of a chain.
|
|
*/
|
|
static int establish_migrate_target(int node, nodemask_t *used,
|
|
int best_distance)
|
|
{
|
|
int migration_target, index, val;
|
|
struct demotion_nodes *nd;
|
|
|
|
if (!node_demotion)
|
|
return NUMA_NO_NODE;
|
|
|
|
nd = &node_demotion[node];
|
|
|
|
migration_target = find_next_best_node(node, used);
|
|
if (migration_target == NUMA_NO_NODE)
|
|
return NUMA_NO_NODE;
|
|
|
|
/*
|
|
* If the node has been set a migration target node before,
|
|
* which means it's the best distance between them. Still
|
|
* check if this node can be demoted to other target nodes
|
|
* if they have a same best distance.
|
|
*/
|
|
if (best_distance != -1) {
|
|
val = node_distance(node, migration_target);
|
|
if (val > best_distance)
|
|
return NUMA_NO_NODE;
|
|
}
|
|
|
|
index = nd->nr;
|
|
if (WARN_ONCE(index >= DEMOTION_TARGET_NODES,
|
|
"Exceeds maximum demotion target nodes\n"))
|
|
return NUMA_NO_NODE;
|
|
|
|
nd->nodes[index] = migration_target;
|
|
nd->nr++;
|
|
|
|
return migration_target;
|
|
}
|
|
|
|
/*
|
|
* When memory fills up on a node, memory contents can be
|
|
* automatically migrated to another node instead of
|
|
* discarded at reclaim.
|
|
*
|
|
* Establish a "migration path" which will start at nodes
|
|
* with CPUs and will follow the priorities used to build the
|
|
* page allocator zonelists.
|
|
*
|
|
* The difference here is that cycles must be avoided. If
|
|
* node0 migrates to node1, then neither node1, nor anything
|
|
* node1 migrates to can migrate to node0. Also one node can
|
|
* be migrated to multiple nodes if the target nodes all have
|
|
* a same best-distance against the source node.
|
|
*
|
|
* This function can run simultaneously with readers of
|
|
* node_demotion[]. However, it can not run simultaneously
|
|
* with itself. Exclusion is provided by memory hotplug events
|
|
* being single-threaded.
|
|
*/
|
|
static void __set_migration_target_nodes(void)
|
|
{
|
|
nodemask_t next_pass = NODE_MASK_NONE;
|
|
nodemask_t this_pass = NODE_MASK_NONE;
|
|
nodemask_t used_targets = NODE_MASK_NONE;
|
|
int node, best_distance;
|
|
|
|
/*
|
|
* Avoid any oddities like cycles that could occur
|
|
* from changes in the topology. This will leave
|
|
* a momentary gap when migration is disabled.
|
|
*/
|
|
disable_all_migrate_targets();
|
|
|
|
/*
|
|
* Allocations go close to CPUs, first. Assume that
|
|
* the migration path starts at the nodes with CPUs.
|
|
*/
|
|
next_pass = node_states[N_CPU];
|
|
again:
|
|
this_pass = next_pass;
|
|
next_pass = NODE_MASK_NONE;
|
|
/*
|
|
* To avoid cycles in the migration "graph", ensure
|
|
* that migration sources are not future targets by
|
|
* setting them in 'used_targets'. Do this only
|
|
* once per pass so that multiple source nodes can
|
|
* share a target node.
|
|
*
|
|
* 'used_targets' will become unavailable in future
|
|
* passes. This limits some opportunities for
|
|
* multiple source nodes to share a destination.
|
|
*/
|
|
nodes_or(used_targets, used_targets, this_pass);
|
|
|
|
for_each_node_mask(node, this_pass) {
|
|
best_distance = -1;
|
|
|
|
/*
|
|
* Try to set up the migration path for the node, and the target
|
|
* migration nodes can be multiple, so doing a loop to find all
|
|
* the target nodes if they all have a best node distance.
|
|
*/
|
|
do {
|
|
int target_node =
|
|
establish_migrate_target(node, &used_targets,
|
|
best_distance);
|
|
|
|
if (target_node == NUMA_NO_NODE)
|
|
break;
|
|
|
|
if (best_distance == -1)
|
|
best_distance = node_distance(node, target_node);
|
|
|
|
/*
|
|
* Visit targets from this pass in the next pass.
|
|
* Eventually, every node will have been part of
|
|
* a pass, and will become set in 'used_targets'.
|
|
*/
|
|
node_set(target_node, next_pass);
|
|
} while (1);
|
|
}
|
|
/*
|
|
* 'next_pass' contains nodes which became migration
|
|
* targets in this pass. Make additional passes until
|
|
* no more migrations targets are available.
|
|
*/
|
|
if (!nodes_empty(next_pass))
|
|
goto again;
|
|
}
|
|
|
|
/*
|
|
* For callers that do not hold get_online_mems() already.
|
|
*/
|
|
static void set_migration_target_nodes(void)
|
|
{
|
|
get_online_mems();
|
|
__set_migration_target_nodes();
|
|
put_online_mems();
|
|
}
|
|
|
|
/*
|
|
* This leaves migrate-on-reclaim transiently disabled between
|
|
* the MEM_GOING_OFFLINE and MEM_OFFLINE events. This runs
|
|
* whether reclaim-based migration is enabled or not, which
|
|
* ensures that the user can turn reclaim-based migration at
|
|
* any time without needing to recalculate migration targets.
|
|
*
|
|
* These callbacks already hold get_online_mems(). That is why
|
|
* __set_migration_target_nodes() can be used as opposed to
|
|
* set_migration_target_nodes().
|
|
*/
|
|
static int __meminit migrate_on_reclaim_callback(struct notifier_block *self,
|
|
unsigned long action, void *_arg)
|
|
{
|
|
struct memory_notify *arg = _arg;
|
|
|
|
/*
|
|
* Only update the node migration order when a node is
|
|
* changing status, like online->offline. This avoids
|
|
* the overhead of synchronize_rcu() in most cases.
|
|
*/
|
|
if (arg->status_change_nid < 0)
|
|
return notifier_from_errno(0);
|
|
|
|
switch (action) {
|
|
case MEM_GOING_OFFLINE:
|
|
/*
|
|
* Make sure there are not transient states where
|
|
* an offline node is a migration target. This
|
|
* will leave migration disabled until the offline
|
|
* completes and the MEM_OFFLINE case below runs.
|
|
*/
|
|
disable_all_migrate_targets();
|
|
break;
|
|
case MEM_OFFLINE:
|
|
case MEM_ONLINE:
|
|
/*
|
|
* Recalculate the target nodes once the node
|
|
* reaches its final state (online or offline).
|
|
*/
|
|
__set_migration_target_nodes();
|
|
break;
|
|
case MEM_CANCEL_OFFLINE:
|
|
/*
|
|
* MEM_GOING_OFFLINE disabled all the migration
|
|
* targets. Reenable them.
|
|
*/
|
|
__set_migration_target_nodes();
|
|
break;
|
|
case MEM_GOING_ONLINE:
|
|
case MEM_CANCEL_ONLINE:
|
|
break;
|
|
}
|
|
|
|
return notifier_from_errno(0);
|
|
}
|
|
|
|
/*
|
|
* React to hotplug events that might affect the migration targets
|
|
* like events that online or offline NUMA nodes.
|
|
*
|
|
* The ordering is also currently dependent on which nodes have
|
|
* CPUs. That means we need CPU on/offline notification too.
|
|
*/
|
|
static int migration_online_cpu(unsigned int cpu)
|
|
{
|
|
set_migration_target_nodes();
|
|
return 0;
|
|
}
|
|
|
|
static int migration_offline_cpu(unsigned int cpu)
|
|
{
|
|
set_migration_target_nodes();
|
|
return 0;
|
|
}
|
|
|
|
static int __init migrate_on_reclaim_init(void)
|
|
{
|
|
int ret;
|
|
|
|
node_demotion = kmalloc_array(nr_node_ids,
|
|
sizeof(struct demotion_nodes),
|
|
GFP_KERNEL);
|
|
WARN_ON(!node_demotion);
|
|
|
|
ret = cpuhp_setup_state_nocalls(CPUHP_MM_DEMOTION_DEAD, "mm/demotion:offline",
|
|
NULL, migration_offline_cpu);
|
|
/*
|
|
* In the unlikely case that this fails, the automatic
|
|
* migration targets may become suboptimal for nodes
|
|
* where N_CPU changes. With such a small impact in a
|
|
* rare case, do not bother trying to do anything special.
|
|
*/
|
|
WARN_ON(ret < 0);
|
|
ret = cpuhp_setup_state(CPUHP_AP_MM_DEMOTION_ONLINE, "mm/demotion:online",
|
|
migration_online_cpu, NULL);
|
|
WARN_ON(ret < 0);
|
|
|
|
hotplug_memory_notifier(migrate_on_reclaim_callback, 100);
|
|
return 0;
|
|
}
|
|
late_initcall(migrate_on_reclaim_init);
|
|
#endif /* CONFIG_HOTPLUG_CPU */
|
|
|
|
bool numa_demotion_enabled = false;
|
|
|
|
#ifdef CONFIG_SYSFS
|
|
static ssize_t numa_demotion_enabled_show(struct kobject *kobj,
|
|
struct kobj_attribute *attr, char *buf)
|
|
{
|
|
return sysfs_emit(buf, "%s\n",
|
|
numa_demotion_enabled ? "true" : "false");
|
|
}
|
|
|
|
static ssize_t numa_demotion_enabled_store(struct kobject *kobj,
|
|
struct kobj_attribute *attr,
|
|
const char *buf, size_t count)
|
|
{
|
|
if (!strncmp(buf, "true", 4) || !strncmp(buf, "1", 1))
|
|
numa_demotion_enabled = true;
|
|
else if (!strncmp(buf, "false", 5) || !strncmp(buf, "0", 1))
|
|
numa_demotion_enabled = false;
|
|
else
|
|
return -EINVAL;
|
|
|
|
return count;
|
|
}
|
|
|
|
static struct kobj_attribute numa_demotion_enabled_attr =
|
|
__ATTR(demotion_enabled, 0644, numa_demotion_enabled_show,
|
|
numa_demotion_enabled_store);
|
|
|
|
static struct attribute *numa_attrs[] = {
|
|
&numa_demotion_enabled_attr.attr,
|
|
NULL,
|
|
};
|
|
|
|
static const struct attribute_group numa_attr_group = {
|
|
.attrs = numa_attrs,
|
|
};
|
|
|
|
static int __init numa_init_sysfs(void)
|
|
{
|
|
int err;
|
|
struct kobject *numa_kobj;
|
|
|
|
numa_kobj = kobject_create_and_add("numa", mm_kobj);
|
|
if (!numa_kobj) {
|
|
pr_err("failed to create numa kobject\n");
|
|
return -ENOMEM;
|
|
}
|
|
err = sysfs_create_group(numa_kobj, &numa_attr_group);
|
|
if (err) {
|
|
pr_err("failed to register numa group\n");
|
|
goto delete_obj;
|
|
}
|
|
return 0;
|
|
|
|
delete_obj:
|
|
kobject_put(numa_kobj);
|
|
return err;
|
|
}
|
|
subsys_initcall(numa_init_sysfs);
|
|
#endif
|