Add a helper function to allow device drivers to create device private transparent huge pages. This is intended to help support device private THP migrations.

Signed-off-by: Ralph Campbell rcampbell@nvidia.com --- include/linux/huge_mm.h | 5 +++++ mm/huge_memory.c | 9 +++++++++ 2 files changed, 14 insertions(+)

diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h index 0365aa97f8e7..3ec26ef27a93 100644 --- a/include/linux/huge_mm.h +++ b/include/linux/huge_mm.h @@ -184,6 +184,7 @@ extern unsigned long thp_get_unmapped_area(struct file *filp, unsigned long flags);

extern void prep_transhuge_page(struct page *page); +extern void prep_transhuge_device_private_page(struct page *page); extern void free_transhuge_page(struct page *page); bool is_transparent_hugepage(struct page *page);

@@ -377,6 +378,10 @@ static inline bool transhuge_vma_suitable(struct vm_area_struct *vma,

static inline void prep_transhuge_page(struct page *page) {}

+static inline void prep_transhuge_device_private_page(struct page *page) +{ +} + static inline bool is_transparent_hugepage(struct page *page) { return false; diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 08a183f6c3ab..b4141f12ff31 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -498,6 +498,15 @@ void prep_transhuge_page(struct page *page) set_compound_page_dtor(page, TRANSHUGE_PAGE_DTOR); }

+void prep_transhuge_device_private_page(struct page *page) +{ + prep_compound_page(page, HPAGE_PMD_ORDER); + prep_transhuge_page(page); + /* Only the head page has a reference to the pgmap. */ + percpu_ref_put_many(page->pgmap->ref, HPAGE_PMD_NR - 1); +} +EXPORT_SYMBOL_GPL(prep_transhuge_device_private_page); + bool is_transparent_hugepage(struct page *page) { if (!PageCompound(page))

Support transparent huge page migration to ZONE_DEVICE private memory. A new selection flag (MIGRATE_VMA_SELECT_COMPOUND) is added to request THP migration. Otherwise, THPs are split when filling in the source PFN array. A new flag (MIGRATE_PFN_COMPOUND) is added to the source PFN array to indicate a huge page can be migrated. If the device driver can allocate a huge page, it sets the MIGRATE_PFN_COMPOUND flag in the destination PFN array. migrate_vma_pages() will fallback to PAGE_SIZE pages if MIGRATE_PFN_COMPOUND is not set in both source and destination arrays.

Signed-off-by: Ralph Campbell rcampbell@nvidia.com --- include/linux/huge_mm.h | 7 + include/linux/memremap.h | 9 + include/linux/migrate.h | 2 + mm/huge_memory.c | 124 +++++++++--- mm/memcontrol.c | 25 ++- mm/memory.c | 10 +- mm/memremap.c | 4 +- mm/migrate.c | 413 ++++++++++++++++++++++++++++++++------- mm/rmap.c | 2 +- 9 files changed, 486 insertions(+), 110 deletions(-)

diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h index 3ec26ef27a93..1e8625cc233c 100644 --- a/include/linux/huge_mm.h +++ b/include/linux/huge_mm.h @@ -190,6 +190,8 @@ bool is_transparent_hugepage(struct page *page);

bool can_split_huge_page(struct page *page, int *pextra_pins); int split_huge_page_to_list(struct page *page, struct list_head *list); +int split_migrating_huge_page(struct vm_area_struct *vma, pmd_t *pmd, + unsigned long address, struct page *page); static inline int split_huge_page(struct page *page) { return split_huge_page_to_list(page, NULL); @@ -456,6 +458,11 @@ static inline bool is_huge_zero_page(struct page *page) return false; }

+static inline bool is_huge_zero_pmd(pmd_t pmd) +{ + return false; +} + static inline bool is_huge_zero_pud(pud_t pud) { return false; diff --git a/include/linux/memremap.h b/include/linux/memremap.h index 86c6c368ce9b..9b39a896af37 100644 --- a/include/linux/memremap.h +++ b/include/linux/memremap.h @@ -87,6 +87,15 @@ struct dev_pagemap_ops { * the page back to a CPU accessible page. */ vm_fault_t (*migrate_to_ram)(struct vm_fault *vmf); + + /* + * Used for private (un-addressable) device memory only. + * This is called when a compound device private page is split. + * The driver uses this callback to set tail_page->pgmap and + * tail_page->zone_device_data appropriately based on the head + * page. + */ + void (*page_split)(struct page *head, struct page *tail_page); };

#define PGMAP_ALTMAP_VALID (1 << 0) diff --git a/include/linux/migrate.h b/include/linux/migrate.h index 0f8d1583fa8e..92179bf360d1 100644 --- a/include/linux/migrate.h +++ b/include/linux/migrate.h @@ -144,6 +144,7 @@ static inline int migrate_misplaced_transhuge_page(struct mm_struct *mm, #define MIGRATE_PFN_MIGRATE (1UL << 1) #define MIGRATE_PFN_LOCKED (1UL << 2) #define MIGRATE_PFN_WRITE (1UL << 3) +#define MIGRATE_PFN_COMPOUND (1UL << 4) #define MIGRATE_PFN_SHIFT 6

static inline struct page *migrate_pfn_to_page(unsigned long mpfn) @@ -161,6 +162,7 @@ static inline unsigned long migrate_pfn(unsigned long pfn) enum migrate_vma_direction { MIGRATE_VMA_SELECT_SYSTEM = 1 << 0, MIGRATE_VMA_SELECT_DEVICE_PRIVATE = 1 << 1, + MIGRATE_VMA_SELECT_COMPOUND = 1 << 2, };

struct migrate_vma { diff --git a/mm/huge_memory.c b/mm/huge_memory.c index b4141f12ff31..a073e66d0ee2 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -1682,23 +1682,35 @@ int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, } else { struct page *page = NULL; int flush_needed = 1; + bool is_anon = false;

if (pmd_present(orig_pmd)) { page = pmd_page(orig_pmd); + is_anon = PageAnon(page); page_remove_rmap(page, true); VM_BUG_ON_PAGE(page_mapcount(page) < 0, page); VM_BUG_ON_PAGE(!PageHead(page), page); } else if (thp_migration_supported()) { swp_entry_t entry;

- VM_BUG_ON(!is_pmd_migration_entry(orig_pmd)); entry = pmd_to_swp_entry(orig_pmd); - page = pfn_to_page(swp_offset(entry)); + if (is_device_private_entry(entry)) { + page = device_private_entry_to_page(entry); + is_anon = PageAnon(page); + page_remove_rmap(page, true); + VM_BUG_ON_PAGE(page_mapcount(page) < 0, page); + VM_BUG_ON_PAGE(!PageHead(page), page); + put_page(page); + } else { + VM_BUG_ON(!is_pmd_migration_entry(orig_pmd)); + page = pfn_to_page(swp_offset(entry)); + is_anon = PageAnon(page); + } flush_needed = 0; } else WARN_ONCE(1, "Non present huge pmd without pmd migration enabled!");

- if (PageAnon(page)) { + if (is_anon) { zap_deposited_table(tlb->mm, pmd); add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR); } else { @@ -2358,9 +2370,10 @@ static void remap_page(struct page *page, unsigned int nr) }

static void __split_huge_page_tail(struct page *head, int tail, - struct lruvec *lruvec, struct list_head *list) + struct lruvec *lruvec, struct list_head *list, bool remap) { struct page *page_tail = head + tail; + int pin_count;

VM_BUG_ON_PAGE(atomic_read(&page_tail->_mapcount) != -1, page_tail);

@@ -2396,15 +2409,24 @@ static void __split_huge_page_tail(struct page *head, int tail, smp_wmb();

/* - * Clear PageTail before unfreezing page refcount. + * A successful get_page_unless_zero() might follow page_ref_unfreeze() + * so PageTail needs to be cleared before unfreezing the page refcount + * in order for compound_head() to work correctly. * - * After successful get_page_unless_zero() might follow put_page() - * which needs correct compound_head(). + * Also, ZONE_DEVICE struct pages share the compound_head field and + * need to restore the pgmap pointer before unfreezing page refcount + * in order for is_zone_device_page() to work correctly. */ - clear_compound_head(page_tail); + if (is_device_private_page(head)) { + head->pgmap->ops->page_split(head, page_tail); + pin_count = 2; + } else { + clear_compound_head(page_tail); + pin_count = 1; + }

/* Finally unfreeze refcount. Additional reference from page cache. */ - page_ref_unfreeze(page_tail, 1 + (!PageAnon(head) || + page_ref_unfreeze(page_tail, pin_count + (!PageAnon(head) || PageSwapCache(head)));

if (page_is_young(head)) @@ -2419,11 +2441,12 @@ static void __split_huge_page_tail(struct page *head, int tail, * pages to show after the currently processed elements - e.g. * migrate_pages */ - lru_add_page_tail(head, page_tail, lruvec, list); + if (remap) + lru_add_page_tail(head, page_tail, lruvec, list); }

static void __split_huge_page(struct page *page, struct list_head *list, - pgoff_t end, unsigned long flags) + pgoff_t end, unsigned long flags, bool remap) { struct page *head = compound_head(page); pg_data_t *pgdat = page_pgdat(head); @@ -2447,7 +2470,7 @@ static void __split_huge_page(struct page *page, struct list_head *list, }

for (i = nr - 1; i >= 1; i--) { - __split_huge_page_tail(head, i, lruvec, list); + __split_huge_page_tail(head, i, lruvec, list, remap); /* Some pages can be beyond i_size: drop them from page cache */ if (head[i].index >= end) { ClearPageDirty(head + i); @@ -2474,6 +2497,9 @@ static void __split_huge_page(struct page *page, struct list_head *list, if (PageSwapCache(head)) { page_ref_add(head, 2); xa_unlock(&swap_cache->i_pages); + } else if (is_device_private_page(head)) { + percpu_ref_get_many(page->pgmap->ref, nr - 1); + page_ref_add(head, 2); } else { page_ref_inc(head); } @@ -2485,6 +2511,9 @@ static void __split_huge_page(struct page *page, struct list_head *list,

spin_unlock_irqrestore(&pgdat->lru_lock, flags);

+ if (!remap) + return; + remap_page(head, nr);

if (PageSwapCache(head)) { @@ -2602,6 +2631,7 @@ bool can_split_huge_page(struct page *page, int *pextra_pins) extra_pins = PageSwapCache(page) ? thp_nr_pages(page) : 0; else extra_pins = thp_nr_pages(page); + extra_pins += is_device_private_page(page); if (pextra_pins) *pextra_pins = extra_pins; return total_mapcount(page) == page_count(page) - extra_pins - 1; @@ -2626,7 +2656,8 @@ bool can_split_huge_page(struct page *page, int *pextra_pins) * Returns -EBUSY if the page is pinned or if anon_vma disappeared from under * us. */ -int split_huge_page_to_list(struct page *page, struct list_head *list) +static int __split_huge_page_to_list(struct page *page, struct list_head *list, + bool remap) { struct page *head = compound_head(page); struct pglist_data *pgdata = NODE_DATA(page_to_nid(head)); @@ -2653,14 +2684,16 @@ int split_huge_page_to_list(struct page *page, struct list_head *list) * is taken to serialise against parallel split or collapse * operations. */ - anon_vma = page_get_anon_vma(head); - if (!anon_vma) { - ret = -EBUSY; - goto out; + if (remap) { + anon_vma = page_get_anon_vma(head); + if (!anon_vma) { + ret = -EBUSY; + goto out; + } + anon_vma_lock_write(anon_vma); } end = -1; mapping = NULL; - anon_vma_lock_write(anon_vma); } else { mapping = head->mapping;

@@ -2686,13 +2719,19 @@ int split_huge_page_to_list(struct page *page, struct list_head *list) /* * Racy check if we can split the page, before unmap_page() will * split PMDs + * If we are splitting a migrating THP, there is no check needed + * because the page is already unmapped and isolated from the LRU. */ - if (!can_split_huge_page(head, &extra_pins)) { + if (!remap) + extra_pins = thp_nr_pages(page) - 1 + + is_device_private_page(head); + else if (!can_split_huge_page(head, &extra_pins)) { ret = -EBUSY; goto out_unlock; }

- unmap_page(head); + if (remap) + unmap_page(head); VM_BUG_ON_PAGE(compound_mapcount(head), head);

/* prevent PageLRU to go away from under us, and freeze lru stats */ @@ -2717,7 +2756,7 @@ int split_huge_page_to_list(struct page *page, struct list_head *list) if (!mapcount && page_ref_freeze(head, 1 + extra_pins)) { if (!list_empty(page_deferred_list(head))) { ds_queue->split_queue_len--; - list_del(page_deferred_list(head)); + list_del_init(page_deferred_list(head)); } spin_unlock(&ds_queue->split_queue_lock); if (mapping) { @@ -2727,7 +2766,7 @@ int split_huge_page_to_list(struct page *page, struct list_head *list) __dec_lruvec_page_state(head, NR_FILE_THPS); }

- __split_huge_page(page, list, end, flags); + __split_huge_page(page, list, end, flags, remap); ret = 0; } else { if (IS_ENABLED(CONFIG_DEBUG_VM) && mapcount) { @@ -2742,7 +2781,8 @@ int split_huge_page_to_list(struct page *page, struct list_head *list) fail: if (mapping) xa_unlock(&mapping->i_pages); spin_unlock_irqrestore(&pgdata->lru_lock, flags); - remap_page(head, thp_nr_pages(head)); + if (remap) + remap_page(head, thp_nr_pages(head)); ret = -EBUSY; }

@@ -2758,6 +2798,36 @@ fail: if (mapping) return ret; }

+int split_huge_page_to_list(struct page *page, struct list_head *list) +{ + return __split_huge_page_to_list(page, list, true); +} + +/* + * Split a migrating huge page. + * The caller should have mmap_lock_read() held, the huge page unmapped and + * isolated, and the PMD page table entry set to a migration entry for the + * given head page. + */ +int split_migrating_huge_page(struct vm_area_struct *vma, pmd_t *pmd, + unsigned long address, struct page *head) +{ + spinlock_t *ptl; + + VM_BUG_ON_PAGE(is_huge_zero_page(head), head); + VM_BUG_ON_PAGE(!PageLocked(head), head); + VM_BUG_ON_PAGE(!PageHead(head), head); + VM_BUG_ON_PAGE(PageWriteback(head), head); + VM_BUG_ON_PAGE(PageLRU(head), head); + VM_BUG_ON_PAGE(compound_mapcount(head), head); + + ptl = pmd_lock(vma->vm_mm, pmd); + __split_huge_pmd_locked(vma, pmd, address, false); + spin_unlock(ptl); + + return __split_huge_page_to_list(head, NULL, false); +} + void free_transhuge_page(struct page *page) { struct deferred_split *ds_queue = get_deferred_split_queue(page); @@ -2766,9 +2836,11 @@ void free_transhuge_page(struct page *page) spin_lock_irqsave(&ds_queue->split_queue_lock, flags); if (!list_empty(page_deferred_list(page))) { ds_queue->split_queue_len--; - list_del(page_deferred_list(page)); + list_del_init(page_deferred_list(page)); } spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags); + if (is_device_private_page(page)) + return; free_compound_page(page); }

@@ -2986,6 +3058,10 @@ void remove_migration_pmd(struct page_vma_mapped_walk *pvmw, struct page *new) pmde = pmd_mksoft_dirty(pmde); if (is_write_migration_entry(entry)) pmde = maybe_pmd_mkwrite(pmde, vma); + if (unlikely(is_device_private_page(new))) { + entry = make_device_private_entry(new, pmd_write(pmde)); + pmde = swp_entry_to_pmd(entry); + }

flush_cache_range(vma, mmun_start, mmun_start + HPAGE_PMD_SIZE); if (PageAnon(new)) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 3a12df292712..12d3d79c4e32 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -5792,12 +5792,22 @@ static enum mc_target_type get_mctgt_type_thp(struct vm_area_struct *vma, struct page *page = NULL; enum mc_target_type ret = MC_TARGET_NONE;

- if (unlikely(is_swap_pmd(pmd))) { - VM_BUG_ON(thp_migration_supported() && - !is_pmd_migration_entry(pmd)); + if (!(mc.flags & MOVE_ANON)) return ret; + if (unlikely(is_swap_pmd(pmd))) { + swp_entry_t entry = pmd_to_swp_entry(pmd); + + if (!is_device_private_entry(entry)) { + VM_BUG_ON(thp_migration_supported() && + !is_pmd_migration_entry(pmd)); + return ret; + } + page = device_private_entry_to_page(entry); + ret = MC_TARGET_DEVICE; + } else { + page = pmd_page(pmd); + ret = MC_TARGET_PAGE; } - page = pmd_page(pmd); VM_BUG_ON_PAGE(!page || !PageHead(page), page); if (!(mc.flags & MOVE_ANON)) return ret; @@ -5828,12 +5838,7 @@ static int mem_cgroup_count_precharge_pte_range(pmd_t *pmd,

ptl = pmd_trans_huge_lock(pmd, vma); if (ptl) { - /* - * Note their can not be MC_TARGET_DEVICE for now as we do not - * support transparent huge page with MEMORY_DEVICE_PRIVATE but - * this might change. - */ - if (get_mctgt_type_thp(vma, addr, *pmd, NULL) == MC_TARGET_PAGE) + if (get_mctgt_type_thp(vma, addr, *pmd, NULL)) mc.precharge += HPAGE_PMD_NR; spin_unlock(ptl); return 0; diff --git a/mm/memory.c b/mm/memory.c index f8d66f0e8da7..963c168a93dc 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -4485,9 +4485,15 @@ static vm_fault_t __handle_mm_fault(struct vm_area_struct *vma,

barrier(); if (unlikely(is_swap_pmd(orig_pmd))) { + swp_entry_t entry = pmd_to_swp_entry(orig_pmd); + + if (is_device_private_entry(entry)) { + vmf.page = device_private_entry_to_page(entry); + return vmf.page->pgmap->ops->migrate_to_ram(&vmf); + } VM_BUG_ON(thp_migration_supported() && - !is_pmd_migration_entry(orig_pmd)); - if (is_pmd_migration_entry(orig_pmd)) + !is_migration_entry(entry)); + if (is_migration_entry(entry)) pmd_migration_entry_wait(mm, vmf.pmd); return 0; } diff --git a/mm/memremap.c b/mm/memremap.c index d72ce30da94e..8b4e6f12e58f 100644 --- a/mm/memremap.c +++ b/mm/memremap.c @@ -92,7 +92,7 @@ static unsigned long pfn_next(unsigned long pfn) { if (pfn % 1024 == 0) cond_resched(); - return pfn + 1; + return pfn + thp_nr_pages(pfn_to_page(pfn)); }

/* @@ -509,6 +509,8 @@ void free_devmap_managed_page(struct page *page) __ClearPageWaiters(page);

mem_cgroup_uncharge(page); + if (PageHead(page)) + free_transhuge_page(page);

/* * When a device_private page is freed, the page->mapping field diff --git a/mm/migrate.c b/mm/migrate.c index 665516319b66..7b69a5f91d0a 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -51,6 +51,7 @@ #include <linux/oom.h>

#include <asm/tlbflush.h> +#include <asm/pgalloc.h>

#define CREATE_TRACE_POINTS #include <trace/events/migrate.h> @@ -2275,19 +2276,28 @@ static int migrate_vma_collect_hole(unsigned long start, { struct migrate_vma *migrate = walk->private; unsigned long addr; + unsigned long mpfn;

/* Only allow populating anonymous memory. */ - if (!vma_is_anonymous(walk->vma)) { - for (addr = start; addr < end; addr += PAGE_SIZE) { - migrate->src[migrate->npages] = 0; - migrate->dst[migrate->npages] = 0; - migrate->npages++; - } - return 0; + if (!vma_is_anonymous(walk->vma) || + !((migrate->flags & MIGRATE_VMA_SELECT_SYSTEM))) + return migrate_vma_collect_skip(start, end, walk); + + if (thp_migration_supported() && + (migrate->flags & MIGRATE_VMA_SELECT_COMPOUND) && + (start & ~PMD_MASK) == 0 && (end & ~PMD_MASK) == 0) { + migrate->src[migrate->npages] = MIGRATE_PFN_MIGRATE | + MIGRATE_PFN_COMPOUND; + migrate->dst[migrate->npages] = 0; + migrate->npages++; + migrate->cpages++; + return migrate_vma_collect_skip(start + PAGE_SIZE, end, walk); }

+ mpfn = (migrate->vma->vm_flags & VM_WRITE) ? + (MIGRATE_PFN_MIGRATE | MIGRATE_PFN_WRITE) : MIGRATE_PFN_MIGRATE; for (addr = start; addr < end; addr += PAGE_SIZE) { - migrate->src[migrate->npages] = MIGRATE_PFN_MIGRATE; + migrate->src[migrate->npages] = mpfn; migrate->dst[migrate->npages] = 0; migrate->npages++; migrate->cpages++; @@ -2296,59 +2306,133 @@ static int migrate_vma_collect_hole(unsigned long start, return 0; }

-static int migrate_vma_collect_pmd(pmd_t *pmdp, - unsigned long start, - unsigned long end, - struct mm_walk *walk) +static int migrate_vma_handle_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; + struct page *page; + unsigned long write = 0; + int ret;

-again: - if (pmd_none(*pmdp)) + ptl = pmd_lock(mm, pmdp); + if (pmd_none(*pmdp)) { + spin_unlock(ptl); 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))) { + if (!(migrate->flags & MIGRATE_VMA_SELECT_SYSTEM)) { spin_unlock(ptl); - goto again; + return migrate_vma_collect_skip(start, end, walk); } - 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; + return migrate_vma_collect_hole(start, end, -1, walk); + } + if (pmd_write(*pmdp)) + write = MIGRATE_PFN_WRITE; + } else if (!pmd_present(*pmdp)) { + swp_entry_t entry = pmd_to_swp_entry(*pmdp); + + if (is_migration_entry(entry)) { + bool wait;

- get_page(page); + page = migration_entry_to_page(entry); + wait = get_page_unless_zero(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 (wait) + put_and_wait_on_page_locked(page); + return -EAGAIN; + } + if (!is_device_private_entry(entry)) { + spin_unlock(ptl); + return migrate_vma_collect_skip(start, end, walk); + } + page = device_private_entry_to_page(entry); + if (!(migrate->flags & MIGRATE_VMA_SELECT_DEVICE_PRIVATE) || + page->pgmap->owner != migrate->pgmap_owner) { + spin_unlock(ptl); + return migrate_vma_collect_skip(start, end, walk); } + if (is_write_device_private_entry(entry)) + write = MIGRATE_PFN_WRITE; + } else { + spin_unlock(ptl); + return -EAGAIN; + } + + get_page(page); + if (unlikely(!trylock_page(page))) { + spin_unlock(ptl); + put_page(page); + return migrate_vma_collect_skip(start, end, walk); + } + if (thp_migration_supported() && + (migrate->flags & MIGRATE_VMA_SELECT_COMPOUND) && + (start & ~PMD_MASK) == 0 && (start + PMD_SIZE) == end) { + struct page_vma_mapped_walk vmw = { + .vma = vma, + .address = start, + .pmd = pmdp, + .ptl = ptl, + }; + + migrate->src[migrate->npages] = write | + migrate_pfn(page_to_pfn(page)) | + MIGRATE_PFN_MIGRATE | MIGRATE_PFN_LOCKED | + MIGRATE_PFN_COMPOUND; + migrate->dst[migrate->npages] = 0; + migrate->npages++; + migrate->cpages++; + migrate_vma_collect_skip(start + PAGE_SIZE, end, walk); + + /* Note this also removes the page from the rmap. */ + set_pmd_migration_entry(&vmw, page); + spin_unlock(ptl); + + return 0; + } + spin_unlock(ptl); + + 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); + + /* This just causes migrate_vma_collect_pmd() to handle PTEs. */ + return -ENOENT; +} + +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_trans_huge(*pmdp) || !pmd_present(*pmdp)) { + int ret = migrate_vma_handle_pmd(pmdp, start, end, walk); + + if (!ret) + return 0; + if (ret == -EAGAIN) + goto again; }

- if (unlikely(pmd_bad(*pmdp))) + if (unlikely(pmd_bad(*pmdp) || pmd_devmap(*pmdp))) return migrate_vma_collect_skip(start, end, walk);

ptep = pte_offset_map_lock(mm, pmdp, addr, &ptl); @@ -2404,8 +2488,7 @@ static int migrate_vma_collect_pmd(pmd_t *pmdp, mpfn |= pte_write(pte) ? MIGRATE_PFN_WRITE : 0; }

- /* FIXME support THP */ - if (!page || !page->mapping || PageTransCompound(page)) { + if (!page || !page->mapping) { mpfn = 0; goto next; } @@ -2527,14 +2610,6 @@ static bool migrate_vma_check_page(struct page *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)) { /* @@ -2833,13 +2908,191 @@ int migrate_vma_setup(struct migrate_vma *args) } EXPORT_SYMBOL(migrate_vma_setup);

+static pmd_t *find_pmd(struct mm_struct *mm, unsigned long addr) +{ + pgd_t *pgdp; + p4d_t *p4dp; + pud_t *pudp; + + pgdp = pgd_offset(mm, addr); + p4dp = p4d_alloc(mm, pgdp, addr); + if (!p4dp) + return NULL; + pudp = pud_alloc(mm, p4dp, addr); + if (!pudp) + return NULL; + return pmd_alloc(mm, pudp, addr); +} + +#ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION +/* + * This code closely follows: + * do_huge_pmd_anonymous_page() + * __do_huge_pmd_anonymous_page() + * except that the page being inserted is likely to be a device private page + * instead of an allocated or zero page. + */ +static int insert_huge_pmd_anonymous_page(struct vm_area_struct *vma, + unsigned long haddr, + struct page *page, + unsigned long *src, + pmd_t *pmdp) +{ + struct mm_struct *mm = vma->vm_mm; + unsigned int i; + spinlock_t *ptl; + bool flush = false; + pgtable_t pgtable; + gfp_t gfp; + pmd_t entry; + + if (WARN_ON_ONCE(compound_order(page) != HPAGE_PMD_ORDER)) + goto abort; + + if (unlikely(anon_vma_prepare(vma))) + goto abort; + + prep_transhuge_page(page); + + gfp = GFP_TRANSHUGE_LIGHT; + if (mem_cgroup_charge(page, mm, gfp)) + goto abort; + + pgtable = pte_alloc_one(mm); + if (unlikely(!pgtable)) + goto abort; + + __SetPageUptodate(page); + + if (is_zone_device_page(page)) { + if (!is_device_private_page(page)) + goto pgtable_abort; + entry = swp_entry_to_pmd(make_device_private_entry(page, + vma->vm_flags & VM_WRITE)); + } else { + entry = mk_huge_pmd(page, vma->vm_page_prot); + entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); + } + + ptl = pmd_lock(mm, pmdp); + + if (check_stable_address_space(mm)) + goto unlock_abort; + + /* + * Check for userfaultfd but do not deliver the fault. Instead, + * just back off. + */ + if (userfaultfd_missing(vma)) + goto unlock_abort; + + if (pmd_present(*pmdp)) { + if (!is_huge_zero_pmd(*pmdp)) + goto unlock_abort; + flush = true; + } else if (!pmd_none(*pmdp)) + goto unlock_abort; + + get_page(page); + page_add_new_anon_rmap(page, vma, haddr, true); + if (!is_zone_device_page(page)) + lru_cache_add_inactive_or_unevictable(page, vma); + if (flush) { + pte_free(mm, pgtable); + flush_cache_range(vma, haddr, haddr + HPAGE_PMD_SIZE); + pmdp_invalidate(vma, haddr, pmdp); + } else { + pgtable_trans_huge_deposit(mm, pmdp, pgtable); + mm_inc_nr_ptes(mm); + } + set_pmd_at(mm, haddr, pmdp, entry); + update_mmu_cache_pmd(vma, haddr, pmdp); + add_mm_counter(mm, MM_ANONPAGES, HPAGE_PMD_NR); + spin_unlock(ptl); + count_vm_event(THP_FAULT_ALLOC); + count_memcg_event_mm(mm, THP_FAULT_ALLOC); + + return 0; + +unlock_abort: + spin_unlock(ptl); +pgtable_abort: + pte_free(mm, pgtable); +abort: + for (i = 0; i < HPAGE_PMD_NR; i++) + src[i] &= ~MIGRATE_PFN_MIGRATE; + return -EINVAL; +} + +static void migrate_vma_split(struct migrate_vma *migrate, unsigned long i, + unsigned long addr) +{ + const unsigned long npages = i + HPAGE_PMD_NR; + unsigned long mpfn; + unsigned long j; + bool migrating = false; + struct page *page; + + migrate->src[i] &= ~MIGRATE_PFN_COMPOUND; + + /* If no part of the THP is migrating, we can skip splitting. */ + for (j = i; j < npages; j++) { + if (migrate->dst[j] & MIGRATE_PFN_VALID) { + migrating = true; + break; + } + } + if (!migrating) + return; + + mpfn = migrate->src[i]; + page = migrate_pfn_to_page(mpfn); + if (page) { + pmd_t *pmdp; + int ret; + + pmdp = find_pmd(migrate->vma->vm_mm, addr); + if (!pmdp) { + migrate->src[i] = mpfn & ~MIGRATE_PFN_MIGRATE; + return; + } + ret = split_migrating_huge_page(migrate->vma, pmdp, addr, page); + if (ret) { + migrate->src[i] = mpfn & ~MIGRATE_PFN_MIGRATE; + return; + } + while (++i < npages) { + mpfn += 1UL << MIGRATE_PFN_SHIFT; + migrate->src[i] = mpfn; + } + } else { + while (++i < npages) + migrate->src[i] = mpfn; + } +} +#else +static int insert_huge_pmd_anonymous_page(struct vm_area_struct *vma, + unsigned long haddr, + struct page *page, + unsigned long *src, + pmd_t *pmdp) +{ + return 0; +} + +static void migrate_vma_split(struct migrate_vma *migrate, unsigned long i, + unsigned long addr) +{ +} +#endif + /* * 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. + * to map in an anonymous zero page except the struct page is already allocated + * and will likely be a ZONE_DEVICE private page. */ static void migrate_vma_insert_page(struct migrate_vma *migrate, unsigned long addr, @@ -2852,9 +3105,6 @@ static void migrate_vma_insert_page(struct migrate_vma *migrate, bool flush = false; spinlock_t *ptl; pte_t entry; - pgd_t *pgdp; - p4d_t *p4dp; - pud_t *pudp; pmd_t *pmdp; pte_t *ptep;

@@ -2862,19 +3112,25 @@ static void migrate_vma_insert_page(struct migrate_vma *migrate, 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); + pmdp = find_pmd(mm, addr); if (!pmdp) goto abort;

- if (pmd_trans_huge(*pmdp) || pmd_devmap(*pmdp)) - goto abort; + if (thp_migration_supported() && *dst & MIGRATE_PFN_COMPOUND) { + int ret = insert_huge_pmd_anonymous_page(vma, addr, page, src, + pmdp); + if (ret) + goto abort; + return; + } + if (!pmd_none(*pmdp)) { + if (pmd_trans_huge(*pmdp)) { + if (!is_huge_zero_pmd(*pmdp)) + goto abort; + __split_huge_pmd(vma, pmdp, addr, false, NULL); + } else if (pmd_leaf(*pmdp)) + goto abort; + }

/* * Use pte_alloc() instead of pte_alloc_map(). We can't run @@ -2909,9 +3165,11 @@ static void migrate_vma_insert_page(struct migrate_vma *migrate, if (is_device_private_page(page)) { swp_entry_t swp_entry;

- swp_entry = make_device_private_entry(page, vma->vm_flags & VM_WRITE); + swp_entry = make_device_private_entry(page, + vma->vm_flags & VM_WRITE); entry = swp_entry_to_pte(swp_entry); - } + } else + goto abort; } else { entry = mk_pte(page, vma->vm_page_prot); if (vma->vm_flags & VM_WRITE) @@ -2940,10 +3198,10 @@ static void migrate_vma_insert_page(struct migrate_vma *migrate, goto unlock_abort;

inc_mm_counter(mm, MM_ANONPAGES); + get_page(page); 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)); @@ -2957,7 +3215,6 @@ static void migrate_vma_insert_page(struct migrate_vma *migrate, }

pte_unmap_unlock(ptep, ptl); - *src = MIGRATE_PFN_MIGRATE; return;

unlock_abort: @@ -2988,11 +3245,23 @@ void migrate_vma_pages(struct migrate_vma *migrate) struct address_space *mapping; int r;

+ /* + * If the caller didn't allocate a THP, split the PMD and + * fix up the src array. + */ + if (thp_migration_supported() && + (migrate->src[i] & MIGRATE_PFN_MIGRATE) && + (migrate->src[i] & MIGRATE_PFN_COMPOUND) && + !(migrate->dst[i] & MIGRATE_PFN_COMPOUND)) + migrate_vma_split(migrate, i, addr); + + newpage = migrate_pfn_to_page(migrate->dst[i]); if (!newpage) { migrate->src[i] &= ~MIGRATE_PFN_MIGRATE; continue; }

+ page = migrate_pfn_to_page(migrate->src[i]); if (!page) { if (!(migrate->src[i] & MIGRATE_PFN_MIGRATE)) continue; diff --git a/mm/rmap.c b/mm/rmap.c index 1b84945d655c..13eb0247d8b7 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -1497,7 +1497,7 @@ static bool try_to_unmap_one(struct page *page, struct vm_area_struct *vma, }

if (IS_ENABLED(CONFIG_MIGRATION) && - (flags & TTU_MIGRATION) && + (flags & (TTU_MIGRATION | TTU_SPLIT_FREEZE)) && is_zone_device_page(page)) { swp_entry_t entry; pte_t swp_pte;

Add some basic stand alone self tests for migrating system memory to device private memory and back.

Signed-off-by: Ralph Campbell rcampbell@nvidia.com --- lib/test_hmm.c | 437 +++++++++++++++++++++---- lib/test_hmm_uapi.h | 3 + tools/testing/selftests/vm/hmm-tests.c | 404 +++++++++++++++++++++++ 3 files changed, 775 insertions(+), 69 deletions(-)

diff --git a/lib/test_hmm.c b/lib/test_hmm.c index 80a78877bd93..456f1a90bcc3 100644 --- a/lib/test_hmm.c +++ b/lib/test_hmm.c @@ -66,6 +66,7 @@ struct dmirror { struct xarray pt; struct mmu_interval_notifier notifier; struct mutex mutex; + __u64 flags; };

/* @@ -91,6 +92,7 @@ struct dmirror_device { unsigned long calloc; unsigned long cfree; struct page *free_pages; + struct page *free_huge_pages; spinlock_t lock; /* protects the above */ };

@@ -450,6 +452,7 @@ static int dmirror_write(struct dmirror *dmirror, struct hmm_dmirror_cmd *cmd) }

static bool dmirror_allocate_chunk(struct dmirror_device *mdevice, + bool is_huge, struct page **ppage) { struct dmirror_chunk *devmem; @@ -503,28 +506,51 @@ static bool dmirror_allocate_chunk(struct dmirror_device *mdevice,

mutex_unlock(&mdevice->devmem_lock);

- pr_info("added new %u MB chunk (total %u chunks, %u MB) PFNs [0x%lx 0x%lx)\n", + pr_info("dev %u added %u MB (total %u chunks, %u MB) PFNs [0x%lx 0x%lx)\n", + MINOR(mdevice->cdevice.dev), DEVMEM_CHUNK_SIZE / (1024 * 1024), mdevice->devmem_count, mdevice->devmem_count * (DEVMEM_CHUNK_SIZE / (1024 * 1024)), pfn_first, pfn_last);

spin_lock(&mdevice->lock); - for (pfn = pfn_first; pfn < pfn_last; pfn++) { + for (pfn = pfn_first; pfn < pfn_last; ) { struct page *page = pfn_to_page(pfn);

+ if (is_huge && (pfn & (HPAGE_PMD_NR - 1)) == 0 && + pfn + HPAGE_PMD_NR <= pfn_last) { + prep_transhuge_device_private_page(page); + page->zone_device_data = mdevice->free_huge_pages; + mdevice->free_huge_pages = page; + pfn += HPAGE_PMD_NR; + continue; + } page->zone_device_data = mdevice->free_pages; mdevice->free_pages = page; + pfn++; } if (ppage) { - *ppage = mdevice->free_pages; - mdevice->free_pages = (*ppage)->zone_device_data; - mdevice->calloc++; + if (is_huge) { + if (!mdevice->free_huge_pages) + goto err_unlock; + *ppage = mdevice->free_huge_pages; + mdevice->free_huge_pages = (*ppage)->zone_device_data; + mdevice->calloc += thp_nr_pages(*ppage); + } else if (mdevice->free_pages) { + *ppage = mdevice->free_pages; + mdevice->free_pages = (*ppage)->zone_device_data; + mdevice->calloc++; + } else + goto err_unlock; } spin_unlock(&mdevice->lock);

return true;

+err_unlock: + spin_unlock(&mdevice->lock); + return false; + err_release: mutex_unlock(&mdevice->devmem_lock); release_mem_region(devmem->pagemap.range.start, range_len(&devmem->pagemap.range)); @@ -534,7 +560,8 @@ static bool dmirror_allocate_chunk(struct dmirror_device *mdevice, return false; }

-static struct page *dmirror_devmem_alloc_page(struct dmirror_device *mdevice) +static struct page *dmirror_devmem_alloc_page(struct dmirror_device *mdevice, + bool is_huge) { struct page *dpage = NULL; struct page *rpage; @@ -549,17 +576,40 @@ static struct page *dmirror_devmem_alloc_page(struct dmirror_device *mdevice)

spin_lock(&mdevice->lock);

- if (mdevice->free_pages) { + if (is_huge && mdevice->free_huge_pages) { + dpage = mdevice->free_huge_pages; + mdevice->free_huge_pages = dpage->zone_device_data; + mdevice->calloc += thp_nr_pages(dpage); + spin_unlock(&mdevice->lock); + } else if (!is_huge && mdevice->free_pages) { dpage = mdevice->free_pages; mdevice->free_pages = dpage->zone_device_data; mdevice->calloc++; spin_unlock(&mdevice->lock); } else { spin_unlock(&mdevice->lock); - if (!dmirror_allocate_chunk(mdevice, &dpage)) + if (!dmirror_allocate_chunk(mdevice, is_huge, &dpage)) goto error; }

+ if (is_huge) { + unsigned int nr_pages = thp_nr_pages(dpage); + unsigned int i; + struct page **tpage; + + tpage = kmap(rpage); + for (i = 0; i < nr_pages; i++, tpage++) { + *tpage = alloc_page(GFP_HIGHUSER); + if (!*tpage) { + while (i--) + __free_page(*--tpage); + kunmap(rpage); + goto error; + } + } + kunmap(rpage); + } + dpage->zone_device_data = rpage; get_page(dpage); lock_page(dpage); @@ -570,22 +620,26 @@ static struct page *dmirror_devmem_alloc_page(struct dmirror_device *mdevice) return NULL; }

-static void dmirror_migrate_alloc_and_copy(struct migrate_vma *args, - struct dmirror *dmirror) +static int dmirror_migrate_alloc_and_copy(struct migrate_vma *args, + struct dmirror *dmirror) { struct dmirror_device *mdevice = dmirror->mdevice; const unsigned long *src = args->src; unsigned long *dst = args->dst; - unsigned long addr; + unsigned long end_pfn = args->end >> PAGE_SHIFT; + unsigned long pfn;

- for (addr = args->start; addr < args->end; addr += PAGE_SIZE, - src++, dst++) { + for (pfn = args->start >> PAGE_SHIFT; pfn < end_pfn; ) { struct page *spage; struct page *dpage; struct page *rpage; + bool is_huge; + unsigned long write; + struct page **tpage; + unsigned long endp;

if (!(*src & MIGRATE_PFN_MIGRATE)) - continue; + goto next;

/* * Note that spage might be NULL which is OK since it is an @@ -593,15 +647,39 @@ static void dmirror_migrate_alloc_and_copy(struct migrate_vma *args, */ spage = migrate_pfn_to_page(*src);

- dpage = dmirror_devmem_alloc_page(mdevice); - if (!dpage) + /* This flag is only set if a whole huge page is migrated. */ + is_huge = *src & MIGRATE_PFN_COMPOUND; + write = (*src & MIGRATE_PFN_WRITE) ? MIGRATE_PFN_WRITE : 0; + + if (dmirror->flags & HMM_DMIRROR_FLAG_FAIL_ALLOC) { + dmirror->flags &= ~HMM_DMIRROR_FLAG_FAIL_ALLOC; + dpage = NULL; + } else + dpage = dmirror_devmem_alloc_page(mdevice, is_huge); + if (!dpage) { + if (!is_huge) + return -ENOMEM; + /* Try falling back to PAGE_SIZE pages. */ + endp = pfn + HPAGE_PMD_NR; + while (pfn < endp) { + dpage = dmirror_devmem_alloc_page(mdevice, + false); + if (!dpage) + return -ENOMEM; + rpage = dpage->zone_device_data; + rpage->zone_device_data = dmirror; + *dst = migrate_pfn(page_to_pfn(dpage)) | + MIGRATE_PFN_LOCKED | write; + if (spage) + copy_highpage(rpage, spage++); + else + clear_highpage(rpage); + pfn++; + src++; + dst++; + } continue; - - rpage = dpage->zone_device_data; - if (spage) - copy_highpage(rpage, spage); - else - clear_highpage(rpage); + }

/* * Normally, a device would use the page->zone_device_data to @@ -609,14 +687,40 @@ static void dmirror_migrate_alloc_and_copy(struct migrate_vma *args, * the simulated device memory and that page holds the pointer * to the mirror. */ + rpage = dpage->zone_device_data; rpage->zone_device_data = dmirror;

- *dst = migrate_pfn(page_to_pfn(dpage)) | - MIGRATE_PFN_LOCKED; - if ((*src & MIGRATE_PFN_WRITE) || - (!spage && args->vma->vm_flags & VM_WRITE)) - *dst |= MIGRATE_PFN_WRITE; + *dst = migrate_pfn(page_to_pfn(dpage)) | MIGRATE_PFN_LOCKED | + write; + + if (is_huge) { + endp = pfn + thp_nr_pages(dpage); + *dst |= MIGRATE_PFN_COMPOUND; + tpage = kmap(rpage); + while (pfn < endp) { + if (spage) + copy_highpage(*tpage, spage++); + else + clear_highpage(*tpage); + tpage++; + pfn++; + src++; + dst++; + } + kunmap(rpage); + continue; + } + + if (spage) + copy_highpage(rpage, spage); + else + clear_highpage(rpage); +next: + pfn++; + src++; + dst++; } + return 0; }

static int dmirror_migrate_finalize_and_map(struct migrate_vma *args, @@ -627,38 +731,75 @@ static int dmirror_migrate_finalize_and_map(struct migrate_vma *args, const unsigned long *src = args->src; const unsigned long *dst = args->dst; unsigned long pfn; + int ret = 0;

/* Map the migrated pages into the device's page tables. */ mutex_lock(&dmirror->mutex);

- for (pfn = start >> PAGE_SHIFT; pfn < (end >> PAGE_SHIFT); pfn++, - src++, dst++) { + for (pfn = start >> PAGE_SHIFT; pfn < (end >> PAGE_SHIFT); ) { + unsigned long mpfn; struct page *dpage; + struct page *rpage; void *entry;

if (!(*src & MIGRATE_PFN_MIGRATE)) - continue; + goto next;

- dpage = migrate_pfn_to_page(*dst); + mpfn = *dst; + dpage = migrate_pfn_to_page(mpfn); if (!dpage) - continue; + goto next;

/* * Store the page that holds the data so the page table * doesn't have to deal with ZONE_DEVICE private pages. */ - entry = dpage->zone_device_data; - if (*dst & MIGRATE_PFN_WRITE) + rpage = dpage->zone_device_data; + if (mpfn & MIGRATE_PFN_COMPOUND) { + struct page **tpage; + unsigned long end_pfn = pfn + thp_nr_pages(dpage); + + ret = 0; + tpage = kmap(rpage); + while (pfn < end_pfn) { + entry = *tpage; + if (mpfn & MIGRATE_PFN_WRITE) + entry = xa_tag_pointer(entry, + DPT_XA_TAG_WRITE); + entry = xa_store(&dmirror->pt, pfn, entry, + GFP_KERNEL); + if (xa_is_err(entry)) { + ret = xa_err(entry); + break; + } + tpage++; + pfn++; + src++; + dst++; + } + kunmap(rpage); + if (ret) + goto err; + continue; + } + + entry = rpage; + if (mpfn & MIGRATE_PFN_WRITE) entry = xa_tag_pointer(entry, DPT_XA_TAG_WRITE); entry = xa_store(&dmirror->pt, pfn, entry, GFP_ATOMIC); if (xa_is_err(entry)) { - mutex_unlock(&dmirror->mutex); - return xa_err(entry); + ret = xa_err(entry); + goto err; } +next: + pfn++; + src++; + dst++; }

+err: mutex_unlock(&dmirror->mutex); - return 0; + return ret; }

static int dmirror_migrate(struct dmirror *dmirror, @@ -668,8 +809,8 @@ static int dmirror_migrate(struct dmirror *dmirror, unsigned long size = cmd->npages << PAGE_SHIFT; struct mm_struct *mm = dmirror->notifier.mm; struct vm_area_struct *vma; - unsigned long src_pfns[64]; - unsigned long dst_pfns[64]; + unsigned long *src_pfns; + unsigned long *dst_pfns; struct dmirror_bounce bounce; struct migrate_vma args; unsigned long next; @@ -684,6 +825,17 @@ static int dmirror_migrate(struct dmirror *dmirror, if (!mmget_not_zero(mm)) return -EINVAL;

+ src_pfns = kmalloc_array(PTRS_PER_PTE, sizeof(*src_pfns), GFP_KERNEL); + if (!src_pfns) { + ret = -ENOMEM; + goto out_put; + } + dst_pfns = kmalloc_array(PTRS_PER_PTE, sizeof(*dst_pfns), GFP_KERNEL); + if (!dst_pfns) { + ret = -ENOMEM; + goto out_free_src; + } + mmap_read_lock(mm); for (addr = start; addr < end; addr = next) { vma = find_vma(mm, addr); @@ -692,7 +844,7 @@ static int dmirror_migrate(struct dmirror *dmirror, ret = -EINVAL; goto out; } - next = min(end, addr + (ARRAY_SIZE(src_pfns) << PAGE_SHIFT)); + next = pmd_addr_end(addr, end); if (next > vma->vm_end) next = vma->vm_end;

@@ -702,17 +854,24 @@ static int dmirror_migrate(struct dmirror *dmirror, args.start = addr; args.end = next; args.pgmap_owner = dmirror->mdevice; - args.flags = MIGRATE_VMA_SELECT_SYSTEM; + args.flags = MIGRATE_VMA_SELECT_SYSTEM | + MIGRATE_VMA_SELECT_COMPOUND; ret = migrate_vma_setup(&args); if (ret) goto out;

- dmirror_migrate_alloc_and_copy(&args, dmirror); - migrate_vma_pages(&args); - dmirror_migrate_finalize_and_map(&args, dmirror); + ret = dmirror_migrate_alloc_and_copy(&args, dmirror); + if (!ret) { + migrate_vma_pages(&args); + dmirror_migrate_finalize_and_map(&args, dmirror); + } migrate_vma_finalize(&args); + if (ret) + goto out; } mmap_read_unlock(mm); + kfree(dst_pfns); + kfree(src_pfns); mmput(mm);

/* Return the migrated data for verification. */ @@ -733,6 +892,10 @@ static int dmirror_migrate(struct dmirror *dmirror,

out: mmap_read_unlock(mm); + kfree(dst_pfns); +out_free_src: + kfree(src_pfns); +out_put: mmput(mm); return ret; } @@ -953,6 +1116,11 @@ static long dmirror_fops_unlocked_ioctl(struct file *filp, ret = dmirror_snapshot(dmirror, &cmd); break;

+ case HMM_DMIRROR_FLAGS: + dmirror->flags = cmd.npages; + ret = 0; + break; + default: return -EINVAL; } @@ -976,22 +1144,70 @@ static const struct file_operations dmirror_fops = { static void dmirror_devmem_free(struct page *page) { struct page *rpage = page->zone_device_data; + unsigned int order = thp_order(page); + unsigned int nr_pages = 1U << order; struct dmirror_device *mdevice;

- if (rpage) + VM_BUG_ON_PAGE(PageTail(page), page); + + if (rpage) { + if (order) { + unsigned int i; + struct page **tpage; + void *kaddr; + + kaddr = kmap_atomic(rpage); + tpage = kaddr; + for (i = 0; i < nr_pages; i++, tpage++) + __free_page(*tpage); + kunmap_atomic(kaddr); + } __free_page(rpage); + }

mdevice = dmirror_page_to_device(page);

spin_lock(&mdevice->lock); - mdevice->cfree++; - page->zone_device_data = mdevice->free_pages; - mdevice->free_pages = page; + if (order) { + page->zone_device_data = mdevice->free_huge_pages; + mdevice->free_huge_pages = page; + } else { + page->zone_device_data = mdevice->free_pages; + mdevice->free_pages = page; + } + mdevice->cfree += nr_pages; spin_unlock(&mdevice->lock); }

+static void dmirror_devmem_split(struct page *head, struct page *page) +{ + struct page *rpage = head->zone_device_data; + unsigned long i; + struct page **tpage; + void *kaddr; + + page->pgmap = head->pgmap; + + if (!rpage) { + page->zone_device_data = NULL; + return; + } + + kaddr = kmap_atomic(rpage); + tpage = kaddr; + i = page - head; + page->zone_device_data = tpage[i]; + if (i == 1) { + head->zone_device_data = tpage[0]; + kunmap_atomic(kaddr); + __free_page(rpage); + } else + kunmap_atomic(kaddr); +} + static vm_fault_t dmirror_devmem_fault_alloc_and_copy(struct migrate_vma *args, - struct dmirror *dmirror) + struct dmirror *dmirror, + unsigned long fault_addr) { const unsigned long *src = args->src; unsigned long *dst = args->dst; @@ -999,25 +1215,71 @@ static vm_fault_t dmirror_devmem_fault_alloc_and_copy(struct migrate_vma *args, unsigned long end = args->end; unsigned long addr;

- for (addr = start; addr < end; addr += PAGE_SIZE, - src++, dst++) { - struct page *dpage, *spage; + for (addr = start; addr < end; ) { + struct page *spage, *dpage; + unsigned int order = 0; + unsigned int nr_pages = 1; + struct page **tpage; + unsigned int i;

spage = migrate_pfn_to_page(*src); if (!spage || !(*src & MIGRATE_PFN_MIGRATE)) - continue; + goto next; + order = thp_order(spage); + nr_pages = 1U << order; + /* The source page is the ZONE_DEVICE private page. */ spage = spage->zone_device_data;

- dpage = alloc_page_vma(GFP_HIGHUSER_MOVABLE, args->vma, addr); - if (!dpage) - continue; + if (dmirror->flags & HMM_DMIRROR_FLAG_FAIL_ALLOC) { + dmirror->flags &= ~HMM_DMIRROR_FLAG_FAIL_ALLOC; + dpage = NULL; + } else if (order) + dpage = alloc_transhugepage(args->vma, addr); + else + dpage = alloc_pages_vma(GFP_HIGHUSER_MOVABLE, 0, + args->vma, addr, + numa_node_id(), false); + if (!dpage) { + if (!order) + return VM_FAULT_OOM; + /* Try falling back to PAGE_SIZE pages. */ + dpage = alloc_pages_vma(GFP_HIGHUSER_MOVABLE, 0, + args->vma, addr, + numa_node_id(), false); + if (!dpage) + return VM_FAULT_OOM; + lock_page(dpage); + xa_erase(&dmirror->pt, fault_addr >> PAGE_SHIFT); + i = (fault_addr - start) >> PAGE_SHIFT; + dst[i] = migrate_pfn(page_to_pfn(dpage)) | MIGRATE_PFN_LOCKED; + if (*src & MIGRATE_PFN_WRITE) + dst[i] |= MIGRATE_PFN_WRITE; + tpage = kmap(spage); + copy_highpage(dpage, tpage[i]); + kunmap(spage); + goto next; + }

lock_page(dpage); xa_erase(&dmirror->pt, addr >> PAGE_SHIFT); - copy_highpage(dpage, spage); *dst = migrate_pfn(page_to_pfn(dpage)) | MIGRATE_PFN_LOCKED; if (*src & MIGRATE_PFN_WRITE) *dst |= MIGRATE_PFN_WRITE; + if (order) { + *dst |= MIGRATE_PFN_COMPOUND; + tpage = kmap(spage); + for (i = 0; i < nr_pages; i++) { + copy_highpage(dpage, *tpage); + tpage++; + dpage++; + } + kunmap(spage); + } else + copy_highpage(dpage, spage); +next: + addr += PAGE_SIZE << order; + src += nr_pages; + dst += nr_pages; } return 0; } @@ -1027,33 +1289,55 @@ static vm_fault_t dmirror_devmem_fault(struct vm_fault *vmf) struct migrate_vma args; unsigned long src_pfns; unsigned long dst_pfns; + struct page *page; struct page *rpage; + unsigned int order; struct dmirror *dmirror; vm_fault_t ret;

+ page = thp_head(vmf->page); + order = thp_order(page); + /* * Normally, a device would use the page->zone_device_data to point to * the mirror but here we use it to hold the page for the simulated * device memory and that page holds the pointer to the mirror. */ - rpage = vmf->page->zone_device_data; + rpage = page->zone_device_data; dmirror = rpage->zone_device_data;

- /* FIXME demonstrate how we can adjust migrate range */ + if (order) { + args.start = vmf->address & (PAGE_MASK << order); + args.end = args.start + (PAGE_SIZE << order); + args.src = kcalloc(PTRS_PER_PTE, sizeof(*args.src), + GFP_KERNEL); + if (!args.src) + return VM_FAULT_OOM; + args.dst = kcalloc(PTRS_PER_PTE, sizeof(*args.dst), + GFP_KERNEL); + if (!args.dst) { + ret = VM_FAULT_OOM; + goto error_src; + } + } else { + args.start = vmf->address; + args.end = args.start + PAGE_SIZE; + args.src = &src_pfns; + args.dst = &dst_pfns; + } args.vma = vmf->vma; - args.start = vmf->address; - args.end = args.start + PAGE_SIZE; - args.src = &src_pfns; - args.dst = &dst_pfns; args.pgmap_owner = dmirror->mdevice; - args.flags = MIGRATE_VMA_SELECT_DEVICE_PRIVATE; + args.flags = MIGRATE_VMA_SELECT_DEVICE_PRIVATE | + MIGRATE_VMA_SELECT_COMPOUND;

- if (migrate_vma_setup(&args)) - return VM_FAULT_SIGBUS; + if (migrate_vma_setup(&args)) { + ret = VM_FAULT_SIGBUS; + goto error_dst; + }

- ret = dmirror_devmem_fault_alloc_and_copy(&args, dmirror); + ret = dmirror_devmem_fault_alloc_and_copy(&args, dmirror, vmf->address); if (ret) - return ret; + goto error_fin; migrate_vma_pages(&args); /* * No device finalize step is needed since @@ -1061,12 +1345,27 @@ static vm_fault_t dmirror_devmem_fault(struct vm_fault *vmf) * invalidated the device page table. */ migrate_vma_finalize(&args); + if (order) { + kfree(args.dst); + kfree(args.src); + } return 0; + +error_fin: + migrate_vma_finalize(&args); +error_dst: + if (args.dst != &dst_pfns) + kfree(args.dst); +error_src: + if (args.src != &src_pfns) + kfree(args.src); + return ret; }

static const struct dev_pagemap_ops dmirror_devmem_ops = { .page_free = dmirror_devmem_free, .migrate_to_ram = dmirror_devmem_fault, + .page_split = dmirror_devmem_split, };

static int dmirror_device_init(struct dmirror_device *mdevice, int id) @@ -1085,7 +1384,7 @@ static int dmirror_device_init(struct dmirror_device *mdevice, int id) return ret;

/* Build a list of free ZONE_DEVICE private struct pages */ - dmirror_allocate_chunk(mdevice, NULL); + dmirror_allocate_chunk(mdevice, false, NULL);

return 0; } diff --git a/lib/test_hmm_uapi.h b/lib/test_hmm_uapi.h index 670b4ef2a5b6..39e6ef3b67b9 100644 --- a/lib/test_hmm_uapi.h +++ b/lib/test_hmm_uapi.h @@ -33,6 +33,9 @@ struct hmm_dmirror_cmd { #define HMM_DMIRROR_WRITE _IOWR('H', 0x01, struct hmm_dmirror_cmd) #define HMM_DMIRROR_MIGRATE _IOWR('H', 0x02, struct hmm_dmirror_cmd) #define HMM_DMIRROR_SNAPSHOT _IOWR('H', 0x03, struct hmm_dmirror_cmd) +#define HMM_DMIRROR_FLAGS _IOWR('H', 0x04, struct hmm_dmirror_cmd) + +#define HMM_DMIRROR_FLAG_FAIL_ALLOC (1ULL << 0)

/* * Values returned in hmm_dmirror_cmd.ptr for HMM_DMIRROR_SNAPSHOT. diff --git a/tools/testing/selftests/vm/hmm-tests.c b/tools/testing/selftests/vm/hmm-tests.c index 5d1ac691b9f4..069c3cc3c89b 100644 --- a/tools/testing/selftests/vm/hmm-tests.c +++ b/tools/testing/selftests/vm/hmm-tests.c @@ -1485,4 +1485,408 @@ TEST_F(hmm2, double_map) hmm_buffer_free(buffer); }

+/* + * Migrate private anonymous huge empty page. + */ +TEST_F(hmm, migrate_anon_huge_empty) +{ + struct hmm_buffer *buffer; + unsigned long npages; + unsigned long size; + unsigned long i; + void *old_ptr; + void *map; + int *ptr; + int ret; + + size = TWOMEG; + + buffer = malloc(sizeof(*buffer)); + ASSERT_NE(buffer, NULL); + + buffer->fd = -1; + buffer->size = 2 * size; + buffer->mirror = malloc(size); + ASSERT_NE(buffer->mirror, NULL); + memset(buffer->mirror, 0xFF, size); + + buffer->ptr = mmap(NULL, 2 * size, + PROT_READ, + MAP_PRIVATE | MAP_ANONYMOUS, + buffer->fd, 0); + ASSERT_NE(buffer->ptr, MAP_FAILED); + + npages = size >> self->page_shift; + map = (void *)ALIGN((uintptr_t)buffer->ptr, size); + ret = madvise(map, size, MADV_HUGEPAGE); + ASSERT_EQ(ret, 0); + old_ptr = buffer->ptr; + buffer->ptr = map; + + /* Migrate memory to device. */ + ret = hmm_dmirror_cmd(self->fd, HMM_DMIRROR_MIGRATE, buffer, npages); + ASSERT_EQ(ret, 0); + ASSERT_EQ(buffer->cpages, npages); + + /* Check what the device read. */ + for (i = 0, ptr = buffer->mirror; i < size / sizeof(*ptr); ++i) + ASSERT_EQ(ptr[i], 0); + + buffer->ptr = old_ptr; + hmm_buffer_free(buffer); +} + +/* + * Migrate private anonymous huge zero page. + */ +TEST_F(hmm, migrate_anon_huge_zero) +{ + struct hmm_buffer *buffer; + unsigned long npages; + unsigned long size; + unsigned long i; + void *old_ptr; + void *map; + int *ptr; + int ret; + int val; + + size = TWOMEG; + + buffer = malloc(sizeof(*buffer)); + ASSERT_NE(buffer, NULL); + + buffer->fd = -1; + buffer->size = 2 * size; + buffer->mirror = malloc(size); + ASSERT_NE(buffer->mirror, NULL); + memset(buffer->mirror, 0xFF, size); + + buffer->ptr = mmap(NULL, 2 * size, + PROT_READ, + MAP_PRIVATE | MAP_ANONYMOUS, + buffer->fd, 0); + ASSERT_NE(buffer->ptr, MAP_FAILED); + + npages = size >> self->page_shift; + map = (void *)ALIGN((uintptr_t)buffer->ptr, size); + ret = madvise(map, size, MADV_HUGEPAGE); + ASSERT_EQ(ret, 0); + old_ptr = buffer->ptr; + buffer->ptr = map; + + /* Initialize a read-only zero huge page. */ + val = *(int *)buffer->ptr; + ASSERT_EQ(val, 0); + + /* Migrate memory to device. */ + ret = hmm_dmirror_cmd(self->fd, HMM_DMIRROR_MIGRATE, buffer, npages); + ASSERT_EQ(ret, 0); + ASSERT_EQ(buffer->cpages, npages); + + /* Check what the device read. */ + for (i = 0, ptr = buffer->mirror; i < size / sizeof(*ptr); ++i) + ASSERT_EQ(ptr[i], 0); + + /* Fault pages back to system memory and check them. */ + for (i = 0, ptr = buffer->ptr; i < size / sizeof(*ptr); ++i) { + ASSERT_EQ(ptr[i], 0); + /* If it asserts once, it probably will 500,000 times */ + if (ptr[i] != 0) + break; + } + + buffer->ptr = old_ptr; + hmm_buffer_free(buffer); +} + +/* + * Migrate private anonymous huge page and free. + */ +TEST_F(hmm, migrate_anon_huge_free) +{ + struct hmm_buffer *buffer; + unsigned long npages; + unsigned long size; + unsigned long i; + void *old_ptr; + void *map; + int *ptr; + int ret; + + size = TWOMEG; + + buffer = malloc(sizeof(*buffer)); + ASSERT_NE(buffer, NULL); + + buffer->fd = -1; + buffer->size = 2 * size; + buffer->mirror = malloc(size); + ASSERT_NE(buffer->mirror, NULL); + memset(buffer->mirror, 0xFF, size); + + buffer->ptr = mmap(NULL, 2 * size, + PROT_READ | PROT_WRITE, + MAP_PRIVATE | MAP_ANONYMOUS, + buffer->fd, 0); + ASSERT_NE(buffer->ptr, MAP_FAILED); + + npages = size >> self->page_shift; + map = (void *)ALIGN((uintptr_t)buffer->ptr, size); + ret = madvise(map, size, MADV_HUGEPAGE); + ASSERT_EQ(ret, 0); + old_ptr = buffer->ptr; + buffer->ptr = map; + + /* Initialize buffer in system memory. */ + for (i = 0, ptr = buffer->ptr; i < size / sizeof(*ptr); ++i) + ptr[i] = i; + + /* Migrate memory to device. */ + ret = hmm_dmirror_cmd(self->fd, HMM_DMIRROR_MIGRATE, buffer, npages); + ASSERT_EQ(ret, 0); + ASSERT_EQ(buffer->cpages, npages); + + /* Check what the device read. */ + for (i = 0, ptr = buffer->mirror; i < size / sizeof(*ptr); ++i) + ASSERT_EQ(ptr[i], i); + + /* Try freeing it. */ + ret = madvise(map, size, MADV_FREE); + ASSERT_EQ(ret, 0); + + buffer->ptr = old_ptr; + hmm_buffer_free(buffer); +} + +/* + * Migrate private anonymous huge page and fault back to sysmem. + */ +TEST_F(hmm, migrate_anon_huge_fault) +{ + struct hmm_buffer *buffer; + unsigned long npages; + unsigned long size; + unsigned long i; + void *old_ptr; + void *map; + int *ptr; + int ret; + + size = TWOMEG; + + buffer = malloc(sizeof(*buffer)); + ASSERT_NE(buffer, NULL); + + buffer->fd = -1; + buffer->size = 2 * size; + buffer->mirror = malloc(size); + ASSERT_NE(buffer->mirror, NULL); + memset(buffer->mirror, 0xFF, size); + + buffer->ptr = mmap(NULL, 2 * size, + PROT_READ | PROT_WRITE, + MAP_PRIVATE | MAP_ANONYMOUS, + buffer->fd, 0); + ASSERT_NE(buffer->ptr, MAP_FAILED); + + npages = size >> self->page_shift; + map = (void *)ALIGN((uintptr_t)buffer->ptr, size); + ret = madvise(map, size, MADV_HUGEPAGE); + ASSERT_EQ(ret, 0); + old_ptr = buffer->ptr; + buffer->ptr = map; + + /* Initialize buffer in system memory. */ + for (i = 0, ptr = buffer->ptr; i < size / sizeof(*ptr); ++i) + ptr[i] = i; + + /* Migrate memory to device. */ + ret = hmm_dmirror_cmd(self->fd, HMM_DMIRROR_MIGRATE, buffer, npages); + ASSERT_EQ(ret, 0); + ASSERT_EQ(buffer->cpages, npages); + + /* Check what the device read. */ + for (i = 0, ptr = buffer->mirror; i < size / sizeof(*ptr); ++i) + ASSERT_EQ(ptr[i], i); + + /* Fault pages back to system memory and check them. */ + for (i = 0, ptr = buffer->ptr; i < size / sizeof(*ptr); ++i) + ASSERT_EQ(ptr[i], i); + + buffer->ptr = old_ptr; + hmm_buffer_free(buffer); +} + +/* + * Migrate private anonymous huge page with allocation errors. + */ +TEST_F(hmm, migrate_anon_huge_err) +{ + struct hmm_buffer *buffer; + unsigned long npages; + unsigned long size; + unsigned long i; + void *old_ptr; + void *map; + int *ptr; + int ret; + + size = TWOMEG; + + buffer = malloc(sizeof(*buffer)); + ASSERT_NE(buffer, NULL); + + buffer->fd = -1; + buffer->size = 2 * size; + buffer->mirror = malloc(2 * size); + ASSERT_NE(buffer->mirror, NULL); + memset(buffer->mirror, 0xFF, 2 * size); + + old_ptr = mmap(NULL, 2 * size, PROT_READ | PROT_WRITE, + MAP_PRIVATE | MAP_ANONYMOUS, buffer->fd, 0); + ASSERT_NE(old_ptr, MAP_FAILED); + + npages = size >> self->page_shift; + map = (void *)ALIGN((uintptr_t)old_ptr, size); + ret = madvise(map, size, MADV_HUGEPAGE); + ASSERT_EQ(ret, 0); + buffer->ptr = map; + + /* Initialize buffer in system memory. */ + for (i = 0, ptr = buffer->ptr; i < size / sizeof(*ptr); ++i) + ptr[i] = i; + + /* Migrate memory to device but force a THP allocation error. */ + ret = hmm_dmirror_cmd(self->fd, HMM_DMIRROR_FLAGS, buffer, + HMM_DMIRROR_FLAG_FAIL_ALLOC); + ASSERT_EQ(ret, 0); + ret = hmm_dmirror_cmd(self->fd, HMM_DMIRROR_MIGRATE, buffer, npages); + ASSERT_EQ(ret, 0); + ASSERT_EQ(buffer->cpages, npages); + + /* Check what the device read. */ + for (i = 0, ptr = buffer->mirror; i < size / sizeof(*ptr); ++i) + ASSERT_EQ(ptr[i], i); + + /* Try faulting back a single (PAGE_SIZE) page. */ + ptr = buffer->ptr; + ASSERT_EQ(ptr[2048], 2048); + + /* unmap and remap the region to reset things. */ + ret = munmap(old_ptr, 2 * size); + ASSERT_EQ(ret, 0); + old_ptr = mmap(NULL, 2 * size, PROT_READ | PROT_WRITE, + MAP_PRIVATE | MAP_ANONYMOUS, buffer->fd, 0); + ASSERT_NE(old_ptr, MAP_FAILED); + map = (void *)ALIGN((uintptr_t)old_ptr, size); + ret = madvise(map, size, MADV_HUGEPAGE); + ASSERT_EQ(ret, 0); + buffer->ptr = map; + + /* Initialize buffer in system memory. */ + for (i = 0, ptr = buffer->ptr; i < size / sizeof(*ptr); ++i) + ptr[i] = i; + + /* Migrate THP to device. */ + ret = hmm_dmirror_cmd(self->fd, HMM_DMIRROR_MIGRATE, buffer, npages); + ASSERT_EQ(ret, 0); + ASSERT_EQ(buffer->cpages, npages); + + /* + * Force an allocation error when faulting back a THP resident in the + * device. + */ + ret = hmm_dmirror_cmd(self->fd, HMM_DMIRROR_FLAGS, buffer, + HMM_DMIRROR_FLAG_FAIL_ALLOC); + ASSERT_EQ(ret, 0); + ptr = buffer->ptr; + ASSERT_EQ(ptr[2048], 2048); + + buffer->ptr = old_ptr; + hmm_buffer_free(buffer); +} + +/* + * Migrate private anonymous huge zero page with allocation errors. + */ +TEST_F(hmm, migrate_anon_huge_zero_err) +{ + struct hmm_buffer *buffer; + unsigned long npages; + unsigned long size; + unsigned long i; + void *old_ptr; + void *map; + int *ptr; + int ret; + + size = TWOMEG; + + buffer = malloc(sizeof(*buffer)); + ASSERT_NE(buffer, NULL); + + buffer->fd = -1; + buffer->size = 2 * size; + buffer->mirror = malloc(2 * size); + ASSERT_NE(buffer->mirror, NULL); + memset(buffer->mirror, 0xFF, 2 * size); + + old_ptr = mmap(NULL, 2 * size, PROT_READ, + MAP_PRIVATE | MAP_ANONYMOUS, buffer->fd, 0); + ASSERT_NE(old_ptr, MAP_FAILED); + + npages = size >> self->page_shift; + map = (void *)ALIGN((uintptr_t)old_ptr, size); + ret = madvise(map, size, MADV_HUGEPAGE); + ASSERT_EQ(ret, 0); + buffer->ptr = map; + + /* Migrate memory to device but force a THP allocation error. */ + ret = hmm_dmirror_cmd(self->fd, HMM_DMIRROR_FLAGS, buffer, + HMM_DMIRROR_FLAG_FAIL_ALLOC); + ASSERT_EQ(ret, 0); + ret = hmm_dmirror_cmd(self->fd, HMM_DMIRROR_MIGRATE, buffer, npages); + ASSERT_EQ(ret, 0); + ASSERT_EQ(buffer->cpages, npages); + + /* Check what the device read. */ + for (i = 0, ptr = buffer->mirror; i < size / sizeof(*ptr); ++i) + ASSERT_EQ(ptr[i], 0); + + /* Try faulting back a single (PAGE_SIZE) page. */ + ptr = buffer->ptr; + ASSERT_EQ(ptr[2048], 0); + + /* unmap and remap the region to reset things. */ + ret = munmap(old_ptr, 2 * size); + ASSERT_EQ(ret, 0); + old_ptr = mmap(NULL, 2 * size, PROT_READ, + MAP_PRIVATE | MAP_ANONYMOUS, buffer->fd, 0); + ASSERT_NE(old_ptr, MAP_FAILED); + map = (void *)ALIGN((uintptr_t)old_ptr, size); + ret = madvise(map, size, MADV_HUGEPAGE); + ASSERT_EQ(ret, 0); + buffer->ptr = map; + + /* Initialize buffer in system memory (zero THP page). */ + ret = ptr[0]; + ASSERT_EQ(ret, 0); + + /* Migrate memory to device but force a THP allocation error. */ + ret = hmm_dmirror_cmd(self->fd, HMM_DMIRROR_FLAGS, buffer, + HMM_DMIRROR_FLAG_FAIL_ALLOC); + ASSERT_EQ(ret, 0); + ret = hmm_dmirror_cmd(self->fd, HMM_DMIRROR_MIGRATE, buffer, npages); + ASSERT_EQ(ret, 0); + ASSERT_EQ(buffer->cpages, npages); + + /* Fault the device memory back and check it. */ + for (i = 0, ptr = buffer->ptr; i < size / sizeof(*ptr); ++i) + ASSERT_EQ(ptr[i], 0); + + buffer->ptr = old_ptr; + hmm_buffer_free(buffer); +} + TEST_HARNESS_MAIN