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![Baolin Wang](/assets/img/avatar_default.png)
The isolate_lru_page() can only return 0 or -EBUSY, and most users did not care about the negative error of isolate_lru_page(), except one user in add_page_for_migration(). So we can convert the isolate_lru_page() to return a boolean value, which can help to make the code more clear when checking the return value of isolate_lru_page(). Also convert all users' logic of checking the isolation state. No functional changes intended. Link: https://lkml.kernel.org/r/3074c1ab628d9dbf139b33f248a8bc253a3f95f0.1676424378.git.baolin.wang@linux.alibaba.com Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com> Acked-by: David Hildenbrand <david@redhat.com> Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org> Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Reviewed-by: SeongJae Park <sj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
976 lines
27 KiB
C
976 lines
27 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Device Memory Migration functionality.
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*
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* Originally written by Jérôme Glisse.
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*/
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#include <linux/export.h>
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#include <linux/memremap.h>
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#include <linux/migrate.h>
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#include <linux/mm.h>
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#include <linux/mm_inline.h>
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#include <linux/mmu_notifier.h>
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#include <linux/oom.h>
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#include <linux/pagewalk.h>
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#include <linux/rmap.h>
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#include <linux/swapops.h>
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#include <asm/tlbflush.h>
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#include "internal.h"
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static int migrate_vma_collect_skip(unsigned long start,
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unsigned long end,
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struct mm_walk *walk)
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{
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struct migrate_vma *migrate = walk->private;
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unsigned long addr;
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for (addr = start; addr < end; addr += PAGE_SIZE) {
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migrate->dst[migrate->npages] = 0;
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migrate->src[migrate->npages++] = 0;
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}
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return 0;
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}
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static int migrate_vma_collect_hole(unsigned long start,
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unsigned long end,
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__always_unused int depth,
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struct mm_walk *walk)
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{
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struct migrate_vma *migrate = walk->private;
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unsigned long addr;
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/* Only allow populating anonymous memory. */
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if (!vma_is_anonymous(walk->vma))
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return migrate_vma_collect_skip(start, end, walk);
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for (addr = start; addr < end; addr += PAGE_SIZE) {
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migrate->src[migrate->npages] = MIGRATE_PFN_MIGRATE;
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migrate->dst[migrate->npages] = 0;
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migrate->npages++;
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migrate->cpages++;
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}
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return 0;
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}
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static int migrate_vma_collect_pmd(pmd_t *pmdp,
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unsigned long start,
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unsigned long end,
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struct mm_walk *walk)
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{
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struct migrate_vma *migrate = walk->private;
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struct vm_area_struct *vma = walk->vma;
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struct mm_struct *mm = vma->vm_mm;
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unsigned long addr = start, unmapped = 0;
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spinlock_t *ptl;
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pte_t *ptep;
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again:
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if (pmd_none(*pmdp))
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return migrate_vma_collect_hole(start, end, -1, walk);
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if (pmd_trans_huge(*pmdp)) {
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struct page *page;
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ptl = pmd_lock(mm, pmdp);
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if (unlikely(!pmd_trans_huge(*pmdp))) {
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spin_unlock(ptl);
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goto again;
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}
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page = pmd_page(*pmdp);
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if (is_huge_zero_page(page)) {
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spin_unlock(ptl);
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split_huge_pmd(vma, pmdp, addr);
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if (pmd_trans_unstable(pmdp))
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return migrate_vma_collect_skip(start, end,
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walk);
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} else {
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int ret;
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get_page(page);
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spin_unlock(ptl);
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if (unlikely(!trylock_page(page)))
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return migrate_vma_collect_skip(start, end,
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walk);
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ret = split_huge_page(page);
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unlock_page(page);
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put_page(page);
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if (ret)
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return migrate_vma_collect_skip(start, end,
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walk);
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if (pmd_none(*pmdp))
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return migrate_vma_collect_hole(start, end, -1,
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walk);
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}
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}
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if (unlikely(pmd_bad(*pmdp)))
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return migrate_vma_collect_skip(start, end, walk);
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ptep = pte_offset_map_lock(mm, pmdp, addr, &ptl);
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arch_enter_lazy_mmu_mode();
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for (; addr < end; addr += PAGE_SIZE, ptep++) {
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unsigned long mpfn = 0, pfn;
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struct page *page;
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swp_entry_t entry;
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pte_t pte;
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pte = *ptep;
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if (pte_none(pte)) {
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if (vma_is_anonymous(vma)) {
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mpfn = MIGRATE_PFN_MIGRATE;
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migrate->cpages++;
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}
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goto next;
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}
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if (!pte_present(pte)) {
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/*
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* Only care about unaddressable device page special
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* page table entry. Other special swap entries are not
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* migratable, and we ignore regular swapped page.
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*/
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entry = pte_to_swp_entry(pte);
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if (!is_device_private_entry(entry))
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goto next;
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page = pfn_swap_entry_to_page(entry);
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if (!(migrate->flags &
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MIGRATE_VMA_SELECT_DEVICE_PRIVATE) ||
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page->pgmap->owner != migrate->pgmap_owner)
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goto next;
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mpfn = migrate_pfn(page_to_pfn(page)) |
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MIGRATE_PFN_MIGRATE;
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if (is_writable_device_private_entry(entry))
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mpfn |= MIGRATE_PFN_WRITE;
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} else {
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pfn = pte_pfn(pte);
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if (is_zero_pfn(pfn) &&
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(migrate->flags & MIGRATE_VMA_SELECT_SYSTEM)) {
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mpfn = MIGRATE_PFN_MIGRATE;
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migrate->cpages++;
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goto next;
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}
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page = vm_normal_page(migrate->vma, addr, pte);
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if (page && !is_zone_device_page(page) &&
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!(migrate->flags & MIGRATE_VMA_SELECT_SYSTEM))
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goto next;
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else if (page && is_device_coherent_page(page) &&
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(!(migrate->flags & MIGRATE_VMA_SELECT_DEVICE_COHERENT) ||
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page->pgmap->owner != migrate->pgmap_owner))
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goto next;
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mpfn = migrate_pfn(pfn) | MIGRATE_PFN_MIGRATE;
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mpfn |= pte_write(pte) ? MIGRATE_PFN_WRITE : 0;
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}
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/* FIXME support THP */
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if (!page || !page->mapping || PageTransCompound(page)) {
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mpfn = 0;
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goto next;
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}
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/*
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* By getting a reference on the page we pin it and that blocks
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* any kind of migration. Side effect is that it "freezes" the
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* pte.
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*
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* We drop this reference after isolating the page from the lru
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* for non device page (device page are not on the lru and thus
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* can't be dropped from it).
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*/
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get_page(page);
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/*
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* We rely on trylock_page() to avoid deadlock between
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* concurrent migrations where each is waiting on the others
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* page lock. If we can't immediately lock the page we fail this
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* migration as it is only best effort anyway.
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*
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* If we can lock the page it's safe to set up a migration entry
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* now. In the common case where the page is mapped once in a
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* single process setting up the migration entry now is an
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* optimisation to avoid walking the rmap later with
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* try_to_migrate().
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*/
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if (trylock_page(page)) {
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bool anon_exclusive;
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pte_t swp_pte;
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flush_cache_page(vma, addr, pte_pfn(*ptep));
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anon_exclusive = PageAnon(page) && PageAnonExclusive(page);
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if (anon_exclusive) {
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pte = ptep_clear_flush(vma, addr, ptep);
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if (page_try_share_anon_rmap(page)) {
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set_pte_at(mm, addr, ptep, pte);
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unlock_page(page);
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put_page(page);
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mpfn = 0;
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goto next;
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}
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} else {
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pte = ptep_get_and_clear(mm, addr, ptep);
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}
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migrate->cpages++;
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/* Set the dirty flag on the folio now the pte is gone. */
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if (pte_dirty(pte))
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folio_mark_dirty(page_folio(page));
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/* Setup special migration page table entry */
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if (mpfn & MIGRATE_PFN_WRITE)
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entry = make_writable_migration_entry(
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page_to_pfn(page));
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else if (anon_exclusive)
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entry = make_readable_exclusive_migration_entry(
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page_to_pfn(page));
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else
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entry = make_readable_migration_entry(
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page_to_pfn(page));
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if (pte_present(pte)) {
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if (pte_young(pte))
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entry = make_migration_entry_young(entry);
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if (pte_dirty(pte))
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entry = make_migration_entry_dirty(entry);
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}
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swp_pte = swp_entry_to_pte(entry);
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if (pte_present(pte)) {
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if (pte_soft_dirty(pte))
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swp_pte = pte_swp_mksoft_dirty(swp_pte);
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if (pte_uffd_wp(pte))
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swp_pte = pte_swp_mkuffd_wp(swp_pte);
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} else {
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if (pte_swp_soft_dirty(pte))
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swp_pte = pte_swp_mksoft_dirty(swp_pte);
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if (pte_swp_uffd_wp(pte))
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swp_pte = pte_swp_mkuffd_wp(swp_pte);
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}
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set_pte_at(mm, addr, ptep, swp_pte);
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/*
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* This is like regular unmap: we remove the rmap and
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* drop page refcount. Page won't be freed, as we took
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* a reference just above.
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*/
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page_remove_rmap(page, vma, false);
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put_page(page);
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if (pte_present(pte))
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unmapped++;
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} else {
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put_page(page);
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mpfn = 0;
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}
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next:
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migrate->dst[migrate->npages] = 0;
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migrate->src[migrate->npages++] = mpfn;
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}
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/* Only flush the TLB if we actually modified any entries */
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if (unmapped)
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flush_tlb_range(walk->vma, start, end);
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arch_leave_lazy_mmu_mode();
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pte_unmap_unlock(ptep - 1, ptl);
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return 0;
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}
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static const struct mm_walk_ops migrate_vma_walk_ops = {
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.pmd_entry = migrate_vma_collect_pmd,
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.pte_hole = migrate_vma_collect_hole,
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};
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/*
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* migrate_vma_collect() - collect pages over a range of virtual addresses
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* @migrate: migrate struct containing all migration information
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*
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* This will walk the CPU page table. For each virtual address backed by a
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* valid page, it updates the src array and takes a reference on the page, in
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* order to pin the page until we lock it and unmap it.
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*/
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static void migrate_vma_collect(struct migrate_vma *migrate)
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{
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struct mmu_notifier_range range;
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/*
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* Note that the pgmap_owner is passed to the mmu notifier callback so
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* that the registered device driver can skip invalidating device
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* private page mappings that won't be migrated.
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*/
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mmu_notifier_range_init_owner(&range, MMU_NOTIFY_MIGRATE, 0,
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migrate->vma->vm_mm, migrate->start, migrate->end,
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migrate->pgmap_owner);
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mmu_notifier_invalidate_range_start(&range);
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walk_page_range(migrate->vma->vm_mm, migrate->start, migrate->end,
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&migrate_vma_walk_ops, migrate);
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mmu_notifier_invalidate_range_end(&range);
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migrate->end = migrate->start + (migrate->npages << PAGE_SHIFT);
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}
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/*
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* migrate_vma_check_page() - check if page is pinned or not
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* @page: struct page to check
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*
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* Pinned pages cannot be migrated. This is the same test as in
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* folio_migrate_mapping(), except that here we allow migration of a
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* ZONE_DEVICE page.
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*/
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static bool migrate_vma_check_page(struct page *page, struct page *fault_page)
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{
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/*
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* One extra ref because caller holds an extra reference, either from
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* isolate_lru_page() for a regular page, or migrate_vma_collect() for
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* a device page.
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*/
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int extra = 1 + (page == fault_page);
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/*
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* FIXME support THP (transparent huge page), it is bit more complex to
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* check them than regular pages, because they can be mapped with a pmd
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* or with a pte (split pte mapping).
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*/
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if (PageCompound(page))
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return false;
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/* Page from ZONE_DEVICE have one extra reference */
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if (is_zone_device_page(page))
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extra++;
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/* For file back page */
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if (page_mapping(page))
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extra += 1 + page_has_private(page);
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if ((page_count(page) - extra) > page_mapcount(page))
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return false;
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return true;
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}
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/*
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* Unmaps pages for migration. Returns number of source pfns marked as
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* migrating.
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*/
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static unsigned long migrate_device_unmap(unsigned long *src_pfns,
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unsigned long npages,
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struct page *fault_page)
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{
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unsigned long i, restore = 0;
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bool allow_drain = true;
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unsigned long unmapped = 0;
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lru_add_drain();
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for (i = 0; i < npages; i++) {
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struct page *page = migrate_pfn_to_page(src_pfns[i]);
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struct folio *folio;
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if (!page) {
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if (src_pfns[i] & MIGRATE_PFN_MIGRATE)
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unmapped++;
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continue;
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}
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/* ZONE_DEVICE pages are not on LRU */
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if (!is_zone_device_page(page)) {
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if (!PageLRU(page) && allow_drain) {
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/* Drain CPU's pagevec */
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lru_add_drain_all();
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allow_drain = false;
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}
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if (!isolate_lru_page(page)) {
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src_pfns[i] &= ~MIGRATE_PFN_MIGRATE;
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restore++;
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continue;
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}
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/* Drop the reference we took in collect */
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put_page(page);
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}
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folio = page_folio(page);
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if (folio_mapped(folio))
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try_to_migrate(folio, 0);
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if (page_mapped(page) ||
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!migrate_vma_check_page(page, fault_page)) {
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if (!is_zone_device_page(page)) {
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get_page(page);
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putback_lru_page(page);
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}
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src_pfns[i] &= ~MIGRATE_PFN_MIGRATE;
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restore++;
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continue;
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}
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unmapped++;
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}
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for (i = 0; i < npages && restore; i++) {
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struct page *page = migrate_pfn_to_page(src_pfns[i]);
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struct folio *folio;
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if (!page || (src_pfns[i] & MIGRATE_PFN_MIGRATE))
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continue;
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folio = page_folio(page);
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remove_migration_ptes(folio, folio, false);
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src_pfns[i] = 0;
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folio_unlock(folio);
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folio_put(folio);
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restore--;
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}
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return unmapped;
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}
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/*
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* migrate_vma_unmap() - replace page mapping with special migration pte entry
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* @migrate: migrate struct containing all migration information
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*
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* Isolate pages from the LRU and replace mappings (CPU page table pte) with a
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* special migration pte entry and check if it has been pinned. Pinned pages are
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* restored because we cannot migrate them.
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*
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* This is the last step before we call the device driver callback to allocate
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* destination memory and copy contents of original page over to new page.
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*/
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static void migrate_vma_unmap(struct migrate_vma *migrate)
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{
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migrate->cpages = migrate_device_unmap(migrate->src, migrate->npages,
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migrate->fault_page);
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}
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/**
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* migrate_vma_setup() - prepare to migrate a range of memory
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* @args: contains the vma, start, and pfns arrays for the migration
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*
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* Returns: negative errno on failures, 0 when 0 or more pages were migrated
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* without an error.
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*
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* Prepare to migrate a range of memory virtual address range by collecting all
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* the pages backing each virtual address in the range, saving them inside the
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* src array. Then lock those pages and unmap them. Once the pages are locked
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* and unmapped, check whether each page is pinned or not. Pages that aren't
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* pinned have the MIGRATE_PFN_MIGRATE flag set (by this function) in the
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* corresponding src array entry. Then restores any pages that are pinned, by
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* remapping and unlocking those pages.
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*
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* The caller should then allocate destination memory and copy source memory to
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* it for all those entries (ie with MIGRATE_PFN_VALID and MIGRATE_PFN_MIGRATE
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* flag set). Once these are allocated and copied, the caller must update each
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* corresponding entry in the dst array with the pfn value of the destination
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* page and with MIGRATE_PFN_VALID. Destination pages must be locked via
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* lock_page().
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*
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* Note that the caller does not have to migrate all the pages that are marked
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* with MIGRATE_PFN_MIGRATE flag in src array unless this is a migration from
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* device memory to system memory. If the caller cannot migrate a device page
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* back to system memory, then it must return VM_FAULT_SIGBUS, which has severe
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* consequences for the userspace process, so it must be avoided if at all
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* possible.
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*
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* 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;
|
|
if (args->fault_page && !is_device_private_page(args->fault_page))
|
|
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 or coherent 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_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 {
|
|
if (is_zone_device_page(page) &&
|
|
!is_device_coherent_page(page)) {
|
|
pr_warn_once("Unsupported ZONE_DEVICE page type.\n");
|
|
goto abort;
|
|
}
|
|
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);
|
|
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;
|
|
}
|
|
|
|
static void __migrate_device_pages(unsigned long *src_pfns,
|
|
unsigned long *dst_pfns, unsigned long npages,
|
|
struct migrate_vma *migrate)
|
|
{
|
|
struct mmu_notifier_range range;
|
|
unsigned long i;
|
|
bool notified = false;
|
|
|
|
for (i = 0; i < npages; i++) {
|
|
struct page *newpage = migrate_pfn_to_page(dst_pfns[i]);
|
|
struct page *page = migrate_pfn_to_page(src_pfns[i]);
|
|
struct address_space *mapping;
|
|
int r;
|
|
|
|
if (!newpage) {
|
|
src_pfns[i] &= ~MIGRATE_PFN_MIGRATE;
|
|
continue;
|
|
}
|
|
|
|
if (!page) {
|
|
unsigned long addr;
|
|
|
|
if (!(src_pfns[i] & MIGRATE_PFN_MIGRATE))
|
|
continue;
|
|
|
|
/*
|
|
* The only time there is no vma is when called from
|
|
* migrate_device_coherent_page(). However this isn't
|
|
* called if the page could not be unmapped.
|
|
*/
|
|
VM_BUG_ON(!migrate);
|
|
addr = migrate->start + i*PAGE_SIZE;
|
|
if (!notified) {
|
|
notified = true;
|
|
|
|
mmu_notifier_range_init_owner(&range,
|
|
MMU_NOTIFY_MIGRATE, 0,
|
|
migrate->vma->vm_mm, addr, migrate->end,
|
|
migrate->pgmap_owner);
|
|
mmu_notifier_invalidate_range_start(&range);
|
|
}
|
|
migrate_vma_insert_page(migrate, addr, newpage,
|
|
&src_pfns[i]);
|
|
continue;
|
|
}
|
|
|
|
mapping = page_mapping(page);
|
|
|
|
if (is_device_private_page(newpage) ||
|
|
is_device_coherent_page(newpage)) {
|
|
/*
|
|
* For now only support anonymous memory migrating to
|
|
* device private or coherent memory.
|
|
*/
|
|
if (mapping) {
|
|
src_pfns[i] &= ~MIGRATE_PFN_MIGRATE;
|
|
continue;
|
|
}
|
|
} else if (is_zone_device_page(newpage)) {
|
|
/*
|
|
* Other types of ZONE_DEVICE page are not supported.
|
|
*/
|
|
src_pfns[i] &= ~MIGRATE_PFN_MIGRATE;
|
|
continue;
|
|
}
|
|
|
|
if (migrate && migrate->fault_page == page)
|
|
r = migrate_folio_extra(mapping, page_folio(newpage),
|
|
page_folio(page),
|
|
MIGRATE_SYNC_NO_COPY, 1);
|
|
else
|
|
r = migrate_folio(mapping, page_folio(newpage),
|
|
page_folio(page), MIGRATE_SYNC_NO_COPY);
|
|
if (r != MIGRATEPAGE_SUCCESS)
|
|
src_pfns[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);
|
|
}
|
|
|
|
/**
|
|
* migrate_device_pages() - migrate meta-data from src page to dst page
|
|
* @src_pfns: src_pfns returned from migrate_device_range()
|
|
* @dst_pfns: array of pfns allocated by the driver to migrate memory to
|
|
* @npages: number of pages in the range
|
|
*
|
|
* Equivalent to migrate_vma_pages(). This is called to migrate struct page
|
|
* meta-data from source struct page to destination.
|
|
*/
|
|
void migrate_device_pages(unsigned long *src_pfns, unsigned long *dst_pfns,
|
|
unsigned long npages)
|
|
{
|
|
__migrate_device_pages(src_pfns, dst_pfns, npages, NULL);
|
|
}
|
|
EXPORT_SYMBOL(migrate_device_pages);
|
|
|
|
/**
|
|
* 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)
|
|
{
|
|
__migrate_device_pages(migrate->src, migrate->dst, migrate->npages, migrate);
|
|
}
|
|
EXPORT_SYMBOL(migrate_vma_pages);
|
|
|
|
/*
|
|
* migrate_device_finalize() - complete page migration
|
|
* @src_pfns: src_pfns returned from migrate_device_range()
|
|
* @dst_pfns: array of pfns allocated by the driver to migrate memory to
|
|
* @npages: number of pages in the range
|
|
*
|
|
* Completes migration of the page by removing special migration entries.
|
|
* Drivers must ensure copying of page data is complete and visible to the CPU
|
|
* before calling this.
|
|
*/
|
|
void migrate_device_finalize(unsigned long *src_pfns,
|
|
unsigned long *dst_pfns, unsigned long npages)
|
|
{
|
|
unsigned long i;
|
|
|
|
for (i = 0; i < npages; i++) {
|
|
struct folio *dst, *src;
|
|
struct page *newpage = migrate_pfn_to_page(dst_pfns[i]);
|
|
struct page *page = migrate_pfn_to_page(src_pfns[i]);
|
|
|
|
if (!page) {
|
|
if (newpage) {
|
|
unlock_page(newpage);
|
|
put_page(newpage);
|
|
}
|
|
continue;
|
|
}
|
|
|
|
if (!(src_pfns[i] & MIGRATE_PFN_MIGRATE) || !newpage) {
|
|
if (newpage) {
|
|
unlock_page(newpage);
|
|
put_page(newpage);
|
|
}
|
|
newpage = page;
|
|
}
|
|
|
|
src = page_folio(page);
|
|
dst = page_folio(newpage);
|
|
remove_migration_ptes(src, dst, false);
|
|
folio_unlock(src);
|
|
|
|
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_device_finalize);
|
|
|
|
/**
|
|
* 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)
|
|
{
|
|
migrate_device_finalize(migrate->src, migrate->dst, migrate->npages);
|
|
}
|
|
EXPORT_SYMBOL(migrate_vma_finalize);
|
|
|
|
/**
|
|
* migrate_device_range() - migrate device private pfns to normal memory.
|
|
* @src_pfns: array large enough to hold migrating source device private pfns.
|
|
* @start: starting pfn in the range to migrate.
|
|
* @npages: number of pages to migrate.
|
|
*
|
|
* migrate_vma_setup() is similar in concept to migrate_vma_setup() except that
|
|
* instead of looking up pages based on virtual address mappings a range of
|
|
* device pfns that should be migrated to system memory is used instead.
|
|
*
|
|
* This is useful when a driver needs to free device memory but doesn't know the
|
|
* virtual mappings of every page that may be in device memory. For example this
|
|
* is often the case when a driver is being unloaded or unbound from a device.
|
|
*
|
|
* Like migrate_vma_setup() this function will take a reference and lock any
|
|
* migrating pages that aren't free before unmapping them. Drivers may then
|
|
* allocate destination pages and start copying data from the device to CPU
|
|
* memory before calling migrate_device_pages().
|
|
*/
|
|
int migrate_device_range(unsigned long *src_pfns, unsigned long start,
|
|
unsigned long npages)
|
|
{
|
|
unsigned long i, pfn;
|
|
|
|
for (pfn = start, i = 0; i < npages; pfn++, i++) {
|
|
struct page *page = pfn_to_page(pfn);
|
|
|
|
if (!get_page_unless_zero(page)) {
|
|
src_pfns[i] = 0;
|
|
continue;
|
|
}
|
|
|
|
if (!trylock_page(page)) {
|
|
src_pfns[i] = 0;
|
|
put_page(page);
|
|
continue;
|
|
}
|
|
|
|
src_pfns[i] = migrate_pfn(pfn) | MIGRATE_PFN_MIGRATE;
|
|
}
|
|
|
|
migrate_device_unmap(src_pfns, npages, NULL);
|
|
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL(migrate_device_range);
|
|
|
|
/*
|
|
* Migrate a device coherent page back to normal memory. The caller should have
|
|
* a reference on page which will be copied to the new page if migration is
|
|
* successful or dropped on failure.
|
|
*/
|
|
int migrate_device_coherent_page(struct page *page)
|
|
{
|
|
unsigned long src_pfn, dst_pfn = 0;
|
|
struct page *dpage;
|
|
|
|
WARN_ON_ONCE(PageCompound(page));
|
|
|
|
lock_page(page);
|
|
src_pfn = migrate_pfn(page_to_pfn(page)) | MIGRATE_PFN_MIGRATE;
|
|
|
|
/*
|
|
* We don't have a VMA and don't need to walk the page tables to find
|
|
* the source page. So call migrate_vma_unmap() directly to unmap the
|
|
* page as migrate_vma_setup() will fail if args.vma == NULL.
|
|
*/
|
|
migrate_device_unmap(&src_pfn, 1, NULL);
|
|
if (!(src_pfn & MIGRATE_PFN_MIGRATE))
|
|
return -EBUSY;
|
|
|
|
dpage = alloc_page(GFP_USER | __GFP_NOWARN);
|
|
if (dpage) {
|
|
lock_page(dpage);
|
|
dst_pfn = migrate_pfn(page_to_pfn(dpage));
|
|
}
|
|
|
|
migrate_device_pages(&src_pfn, &dst_pfn, 1);
|
|
if (src_pfn & MIGRATE_PFN_MIGRATE)
|
|
copy_highpage(dpage, page);
|
|
migrate_device_finalize(&src_pfn, &dst_pfn, 1);
|
|
|
|
if (src_pfn & MIGRATE_PFN_MIGRATE)
|
|
return 0;
|
|
return -EBUSY;
|
|
}
|