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849 lines
23 KiB
849 lines
23 KiB
// SPDX-License-Identifier: GPL-2.0 |
|
/* |
|
* Device Memory Migration functionality. |
|
* |
|
* Originally written by Jérôme Glisse. |
|
*/ |
|
#include <linux/export.h> |
|
#include <linux/memremap.h> |
|
#include <linux/migrate.h> |
|
#include <linux/mm_inline.h> |
|
#include <linux/mmu_notifier.h> |
|
#include <linux/oom.h> |
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#include <linux/pagewalk.h> |
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#include <linux/rmap.h> |
|
#include <linux/swapops.h> |
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#include <asm/tlbflush.h> |
|
#include "internal.h" |
|
|
|
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; |
|
|
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/* Only allow populating anonymous memory. */ |
|
if (!vma_is_anonymous(walk->vma)) |
|
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++; |
|
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)) |
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return migrate_vma_collect_hole(start, end, -1, walk); |
|
|
|
if (pmd_trans_huge(*pmdp)) { |
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struct page *page; |
|
|
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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); |
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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, |
|
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, |
|
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, |
|
walk); |
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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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} |
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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; |
|
swp_entry_t entry; |
|
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++; |
|
} |
|
goto next; |
|
} |
|
|
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if (!pte_present(pte)) { |
|
/* |
|
* 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 & |
|
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; |
|
} |
|
page = vm_normal_page(migrate->vma, addr, pte); |
|
if (page && !is_zone_device_page(page) && |
|
!(migrate->flags & MIGRATE_VMA_SELECT_SYSTEM)) |
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goto next; |
|
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; |
|
} |
|
|
|
/* |
|
* By getting a reference on the page we pin it and that blocks |
|
* 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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* Optimize for the common case where page is only mapped once |
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* in one process. If we can lock the page, then we can safely |
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* set up a special migration page table entry now. |
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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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anon_exclusive = PageAnon(page) && PageAnonExclusive(page); |
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if (anon_exclusive) { |
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flush_cache_page(vma, addr, pte_pfn(*ptep)); |
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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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ptep_get_and_clear(mm, addr, ptep); |
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} |
|
|
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migrate->cpages++; |
|
|
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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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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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arch_leave_lazy_mmu_mode(); |
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pte_unmap_unlock(ptep - 1, ptl); |
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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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return 0; |
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} |
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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, 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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|
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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 |
|
* 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) |
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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; |
|
|
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/* |
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* 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). |
|
*/ |
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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)) |
|
return false; |
|
|
|
return true; |
|
} |
|
|
|
/* |
|
* migrate_vma_unmap() - replace page mapping with special migration pte entry |
|
* @migrate: migrate struct containing all migration information |
|
* |
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* 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. |
|
* |
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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. |
|
*/ |
|
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]); |
|
struct folio *folio; |
|
|
|
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); |
|
} |
|
|
|
folio = page_folio(page); |
|
if (folio_mapped(folio)) |
|
try_to_migrate(folio, 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]); |
|
struct folio *folio; |
|
|
|
if (!page || (migrate->src[i] & MIGRATE_PFN_MIGRATE)) |
|
continue; |
|
|
|
folio = page_folio(page); |
|
remove_migration_ptes(folio, folio, false); |
|
|
|
migrate->src[i] = 0; |
|
folio_unlock(folio); |
|
folio_put(folio); |
|
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 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; |
|
} |
|
|
|
/** |
|
* 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) { |
|
/* |
|
* 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->vma); |
|
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_device_private_page(newpage) || |
|
is_device_coherent_page(newpage)) { |
|
/* |
|
* For now only support anonymous memory migrating to |
|
* device private or coherent memory. |
|
*/ |
|
if (mapping) { |
|
migrate->src[i] &= ~MIGRATE_PFN_MIGRATE; |
|
continue; |
|
} |
|
} else if (is_zone_device_page(newpage)) { |
|
/* |
|
* Other types of ZONE_DEVICE page are not supported. |
|
*/ |
|
migrate->src[i] &= ~MIGRATE_PFN_MIGRATE; |
|
continue; |
|
} |
|
|
|
r = migrate_folio(mapping, page_folio(newpage), |
|
page_folio(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 folio *dst, *src; |
|
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; |
|
} |
|
|
|
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_vma_finalize); |
|
|
|
/* |
|
* 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 migrate_vma args; |
|
struct page *dpage; |
|
|
|
WARN_ON_ONCE(PageCompound(page)); |
|
|
|
lock_page(page); |
|
src_pfn = migrate_pfn(page_to_pfn(page)) | MIGRATE_PFN_MIGRATE; |
|
args.src = &src_pfn; |
|
args.dst = &dst_pfn; |
|
args.cpages = 1; |
|
args.npages = 1; |
|
args.vma = NULL; |
|
|
|
/* |
|
* 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_vma_unmap(&args); |
|
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_vma_pages(&args); |
|
if (src_pfn & MIGRATE_PFN_MIGRATE) |
|
copy_highpage(dpage, page); |
|
migrate_vma_finalize(&args); |
|
|
|
if (src_pfn & MIGRATE_PFN_MIGRATE) |
|
return 0; |
|
return -EBUSY; |
|
}
|
|
|