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Subject[RFC PATCH v2 14/30] mm: thp: add PUD THP split_huge_pud_page() function.
Date
From: Zi Yan <ziy@nvidia.com>

It mimics PMD-level THP split. In addition, to support PMD-mapped PUD
THP, PMDPageInPUD() is added to identify the first page in the PMD sized
aligned physical pages. For example, in x86_64, the page[0], page[512],
page[1024], ... are regarded as PMDPageInPUD.

For the mapcount of PMD-mapped PUD THP, sub_compound_mapcount() is added
to uses (PMDPageInPUD+3).compound_mapcount as the mapcount, since each
base page's mapcount is used for PTE mapping, first tail page's
compound_mapcount is already in use, and second tail page's
compound_mapcount overlaps with in-use deferred_list.

PagePUDDoubleMap() is added to indicate both PUD-mapped and PMD-mapped
PUD THPs. PageDoubleMap() remains its original meaning, indicating both
PMD-mapped and PTE-mapped THPs.

Signed-off-by: Zi Yan <ziy@nvidia.com>
---
arch/x86/include/asm/pgalloc.h | 9 +
arch/x86/include/asm/pgtable.h | 21 ++
include/linux/huge_mm.h | 31 +-
include/linux/memcontrol.h | 5 +
include/linux/mm.h | 25 +-
include/linux/page-flags.h | 48 +++
include/linux/pgtable.h | 17 ++
include/linux/rmap.h | 1 +
include/linux/swap.h | 2 +
include/linux/vm_event_item.h | 4 +
mm/huge_memory.c | 525 +++++++++++++++++++++++++++++++--
mm/memcontrol.c | 13 +
mm/memory.c | 2 +-
mm/page_alloc.c | 21 +-
mm/pagewalk.c | 2 +-
mm/pgtable-generic.c | 11 +
mm/rmap.c | 93 +++++-
mm/swap.c | 30 ++
mm/util.c | 22 +-
mm/vmstat.c | 4 +
20 files changed, 832 insertions(+), 54 deletions(-)

diff --git a/arch/x86/include/asm/pgalloc.h b/arch/x86/include/asm/pgalloc.h
index b24284522973..f6926725c379 100644
--- a/arch/x86/include/asm/pgalloc.h
+++ b/arch/x86/include/asm/pgalloc.h
@@ -99,6 +99,15 @@ static inline void pmd_populate(struct mm_struct *mm, pmd_t *pmd,

#define pmd_pgtable(pmd) pmd_page(pmd)

+static inline void pud_populate_with_pgtable(struct mm_struct *mm, pud_t *pud,
+ struct page *pte)
+{
+ unsigned long pfn = page_to_pfn(pte);
+
+ paravirt_alloc_pmd(mm, pfn);
+ set_pud(pud, __pud(((pteval_t)pfn << PAGE_SHIFT) | _PAGE_TABLE));
+}
+
#if CONFIG_PGTABLE_LEVELS > 2
static inline pmd_t *pmd_alloc_one_page_with_ptes(struct mm_struct *mm, unsigned long addr)
{
diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h
index 8bf7bfd71a46..575c349e08b2 100644
--- a/arch/x86/include/asm/pgtable.h
+++ b/arch/x86/include/asm/pgtable.h
@@ -630,6 +630,12 @@ static inline pmd_t pmd_mkinvalid(pmd_t pmd)
__pgprot(pmd_flags(pmd) & ~(_PAGE_PRESENT|_PAGE_PROTNONE)));
}

+static inline pud_t pud_mknotpresent(pud_t pud)
+{
+ return pfn_pud(pud_pfn(pud),
+ __pgprot(pud_flags(pud) & ~(_PAGE_PRESENT|_PAGE_PROTNONE)));
+}
+
static inline u64 flip_protnone_guard(u64 oldval, u64 val, u64 mask);

static inline pte_t pte_modify(pte_t pte, pgprot_t newprot)
@@ -1246,6 +1252,21 @@ static inline p4d_t *user_to_kernel_p4dp(p4d_t *p4dp)
}
#endif /* CONFIG_PAGE_TABLE_ISOLATION */

+#ifndef pudp_establish
+#define pudp_establish pudp_establish
+static inline pud_t pudp_establish(struct vm_area_struct *vma,
+ unsigned long address, pud_t *pudp, pud_t pud)
+{
+ if (IS_ENABLED(CONFIG_SMP)) {
+ return xchg(pudp, pud);
+ } else {
+ pud_t old = *pudp;
+ *pudp = pud;
+ return old;
+ }
+}
+#endif
+
/*
* clone_pgd_range(pgd_t *dst, pgd_t *src, int count);
*
diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
index 7528652400e4..e5c68e680907 100644
--- a/include/linux/huge_mm.h
+++ b/include/linux/huge_mm.h
@@ -222,17 +222,27 @@ void __split_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
void split_huge_pmd_address(struct vm_area_struct *vma, unsigned long address,
bool freeze, struct page *page);

+bool can_split_huge_pud_page(struct page *page, int *pextra_pins);
+int split_huge_pud_page_to_list(struct page *page, struct list_head *list);
+static inline int split_huge_pud_page(struct page *page)
+{
+ return split_huge_pud_page_to_list(page, NULL);
+}
void __split_huge_pud(struct vm_area_struct *vma, pud_t *pud,
- unsigned long address);
+ unsigned long address, bool freeze, struct page *page);

#define split_huge_pud(__vma, __pud, __address) \
do { \
pud_t *____pud = (__pud); \
if (pud_trans_huge(*____pud) \
|| pud_devmap(*____pud)) \
- __split_huge_pud(__vma, __pud, __address); \
+ __split_huge_pud(__vma, __pud, __address, \
+ false, NULL); \
} while (0)

+void split_huge_pud_address(struct vm_area_struct *vma, unsigned long address,
+ bool freeze, struct page *page);
+
extern int hugepage_madvise(struct vm_area_struct *vma,
unsigned long *vm_flags, int advice);
extern void vma_adjust_trans_huge(struct vm_area_struct *vma,
@@ -422,8 +432,25 @@ static inline void __split_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
static inline void split_huge_pmd_address(struct vm_area_struct *vma,
unsigned long address, bool freeze, struct page *page) {}

+static inline bool
+can_split_huge_pud_page(struct page *page, int *pextra_pins)
+{
+ BUILD_BUG();
+ return false;
+}
+static inline int
+split_huge_pud_page_to_list(struct page *page, struct list_head *list)
+{
+ return 0;
+}
+static inline int split_huge_pud_page(struct page *page)
+{
+ return 0;
+}
#define split_huge_pud(__vma, __pmd, __address) \
do { } while (0)
+static inline void split_huge_pud_address(struct vm_area_struct *vma,
+ unsigned long address, bool freeze, struct page *page) {}

static inline int hugepage_madvise(struct vm_area_struct *vma,
unsigned long *vm_flags, int advice)
diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index e391e3c56de5..a7622510d43d 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -932,6 +932,7 @@ static inline void memcg_memory_event_mm(struct mm_struct *mm,

#ifdef CONFIG_TRANSPARENT_HUGEPAGE
void mem_cgroup_split_huge_fixup(struct page *head);
+void mem_cgroup_split_huge_pud_fixup(struct page *head);
#endif

#else /* CONFIG_MEMCG */
@@ -1264,6 +1265,10 @@ static inline void mem_cgroup_split_huge_fixup(struct page *head)
{
}

+static inline void mem_cgroup_split_huge_pud_fixup(struct page *head)
+{
+}
+
static inline void count_memcg_events(struct mem_cgroup *memcg,
enum vm_event_item idx,
unsigned long count)
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 8f54f06c8eb6..51b75ffa6a6c 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -801,6 +801,24 @@ static inline int compound_mapcount(struct page *page)
return head_compound_mapcount(page);
}

+static inline unsigned int compound_order(struct page *page);
+static inline atomic_t *sub_compound_mapcount_ptr(struct page *page, int sub_level)
+{
+ struct page *head = compound_head(page);
+
+ VM_BUG_ON_PAGE(!PageCompound(page), page);
+ VM_BUG_ON_PAGE(compound_order(head) != HPAGE_PUD_ORDER, page);
+ VM_BUG_ON_PAGE((page - head) % HPAGE_PMD_NR, page);
+ VM_BUG_ON_PAGE(sub_level != 1, page);
+ return &page[2 + sub_level].compound_mapcount;
+}
+
+/* Only works for PUD pages */
+static inline int sub_compound_mapcount(struct page *page)
+{
+ return atomic_read(sub_compound_mapcount_ptr(page, 1)) + 1;
+}
+
/*
* The atomic page->_mapcount, starts from -1: so that transitions
* both from it and to it can be tracked, using atomic_inc_and_test
@@ -893,13 +911,6 @@ static inline void destroy_compound_page(struct page *page)
compound_page_dtors[page[1].compound_dtor](page);
}

-static inline unsigned int compound_order(struct page *page)
-{
- if (!PageHead(page))
- return 0;
- return page[1].compound_order;
-}
-
static inline bool hpage_pincount_available(struct page *page)
{
/*
diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
index fbbb841a9346..f1bfb02622cf 100644
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h
@@ -235,6 +235,9 @@ static inline void page_init_poison(struct page *page, size_t size)
*
* PF_SECOND:
* the page flag is stored in the first tail page.
+ *
+ * PF_THIRD:
+ * the page flag is stored in the second tail page.
*/
#define PF_POISONED_CHECK(page) ({ \
VM_BUG_ON_PGFLAGS(PagePoisoned(page), page); \
@@ -253,6 +256,9 @@ static inline void page_init_poison(struct page *page, size_t size)
#define PF_SECOND(page, enforce) ({ \
VM_BUG_ON_PGFLAGS(!PageHead(page), page); \
PF_POISONED_CHECK(&page[1]); })
+#define PF_THIRD(page, enforce) ({ \
+ VM_BUG_ON_PGFLAGS(!PageHead(page), page); \
+ PF_POISONED_CHECK(&page[2]); })

/*
* Macros to create function definitions for page flags
@@ -674,6 +680,30 @@ static inline int PageTransTail(struct page *page)
return PageTail(page);
}

+#define HPAGE_PMD_SHIFT PMD_SHIFT
+#define HPAGE_PMD_ORDER (HPAGE_PMD_SHIFT-PAGE_SHIFT)
+#define HPAGE_PMD_NR (1<<HPAGE_PMD_ORDER)
+
+#define HPAGE_PUD_SHIFT PUD_SHIFT
+#define HPAGE_PUD_ORDER (HPAGE_PUD_SHIFT-PAGE_SHIFT)
+#define HPAGE_PUD_NR (1<<HPAGE_PUD_ORDER)
+
+static inline unsigned int compound_order(struct page *page)
+{
+ if (!PageHead(page))
+ return 0;
+ return page[1].compound_order;
+}
+
+
+static inline int PMDPageInPUD(struct page *page)
+{
+ struct page *head = compound_head(page);
+
+ return (PageCompound(page) && compound_order(head) == HPAGE_PUD_ORDER &&
+ ((page - head) % HPAGE_PMD_NR == 0));
+}
+
/*
* PageDoubleMap indicates that the compound page is mapped with PTEs as well
* as PMDs.
@@ -689,13 +719,31 @@ static inline int PageTransTail(struct page *page)
*/
PAGEFLAG(DoubleMap, double_map, PF_SECOND)
TESTSCFLAG(DoubleMap, double_map, PF_SECOND)
+/*
+ * PagePUDDoubleMap indicates that the compound page is mapped with PMDs as well
+ * as PUDs.
+ *
+ * This is required for optimization of rmap operations for THP: we can postpone
+ * per small page mapcount accounting (and its overhead from atomic operations)
+ * until the first PUD split.
+ *
+ * For the page PagePUDDoubleMap means ->_mapcount in all sub-PMD pages is
+ * offset up by one. This reference will go away with last sub_compound_mapcount.
+ *
+ * See also __split_huge_pud_locked() and page_remove_anon_compound_rmap().
+ */
+PAGEFLAG(PUDDoubleMap, double_map, PF_THIRD)
+ TESTSCFLAG(PUDDoubleMap, double_map, PF_THIRD)
#else
TESTPAGEFLAG_FALSE(TransHuge)
TESTPAGEFLAG_FALSE(TransCompound)
TESTPAGEFLAG_FALSE(TransCompoundMap)
TESTPAGEFLAG_FALSE(TransTail)
+TESTPAGEFLAG_FALSE(PMDPageInPUD)
PAGEFLAG_FALSE(DoubleMap)
TESTSCFLAG_FALSE(DoubleMap)
+PAGEFLAG_FALSE(PUDDoubleMap)
+ TESTSETFLAG_FALSE(PUDDoubleMap)
#endif

/*
diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h
index bb163504fb01..02279a97e170 100644
--- a/include/linux/pgtable.h
+++ b/include/linux/pgtable.h
@@ -508,6 +508,11 @@ extern pmd_t pmdp_invalidate(struct vm_area_struct *vma, unsigned long address,
pmd_t *pmdp);
#endif

+#ifndef __HAVE_ARCH_PUDP_INVALIDATE
+extern pud_t pudp_invalidate(struct vm_area_struct *vma, unsigned long address,
+ pud_t *pudp);
+#endif
+
#ifndef __HAVE_ARCH_PTE_SAME
static inline int pte_same(pte_t pte_a, pte_t pte_b)
{
@@ -1161,6 +1166,18 @@ static inline pmd_t pmd_read_atomic(pmd_t *pmdp)
}
#endif

+#ifndef pud_read_atomic
+static inline pud_t pud_read_atomic(pud_t *pudp)
+{
+ /*
+ * Depend on compiler for an atomic pmd read. NOTE: this is
+ * only going to work, if the pmdval_t isn't larger than
+ * an unsigned long.
+ */
+ return *pudp;
+}
+#endif
+
#ifndef arch_needs_pgtable_deposit
#define arch_needs_pgtable_deposit() (false)
#endif
diff --git a/include/linux/rmap.h b/include/linux/rmap.h
index 1244549f3eaf..0680b9fff2b3 100644
--- a/include/linux/rmap.h
+++ b/include/linux/rmap.h
@@ -99,6 +99,7 @@ enum ttu_flags {
TTU_RMAP_LOCKED = 0x80, /* do not grab rmap lock:
* caller holds it */
TTU_SPLIT_FREEZE = 0x100, /* freeze pte under splitting thp */
+ TTU_SPLIT_HUGE_PUD = 0x200, /* split huge PUD if any */
};

#ifdef CONFIG_MMU
diff --git a/include/linux/swap.h b/include/linux/swap.h
index f32804e2fad5..dee400a56e84 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -340,6 +340,8 @@ extern void lru_note_cost_page(struct page *);
extern void lru_cache_add(struct page *);
extern void lru_add_page_tail(struct page *page, struct page *page_tail,
struct lruvec *lruvec, struct list_head *head);
+extern void lru_add_pud_page_tail(struct page *page, struct page *page_tail,
+ struct lruvec *lruvec, struct list_head *head);
extern void mark_page_accessed(struct page *);
extern void lru_add_drain(void);
extern void lru_add_drain_cpu(int cpu);
diff --git a/include/linux/vm_event_item.h b/include/linux/vm_event_item.h
index 416d9966fa3f..cf2b5632b96c 100644
--- a/include/linux/vm_event_item.h
+++ b/include/linux/vm_event_item.h
@@ -97,6 +97,10 @@ enum vm_event_item { PGPGIN, PGPGOUT, PSWPIN, PSWPOUT,
THP_FAULT_FALLBACK_PUD,
THP_FAULT_FALLBACK_PUD_CHARGE,
THP_SPLIT_PUD,
+ THP_SPLIT_PUD_PAGE,
+ THP_SPLIT_PUD_PAGE_FAILED,
+ THP_ZERO_PUD_PAGE_ALLOC,
+ THP_ZERO_PUD_PAGE_ALLOC_FAILED,
#endif
THP_ZERO_PAGE_ALLOC,
THP_ZERO_PAGE_ALLOC_FAILED,
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 6716c5286494..4a899e856088 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1775,7 +1775,7 @@ int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
page = pmd_page(orig_pmd);
page_remove_rmap(page, HPAGE_PMD_ORDER);
VM_BUG_ON_PAGE(page_mapcount(page) < 0, page);
- VM_BUG_ON_PAGE(!PageHead(page), page);
+ VM_BUG_ON_PAGE(!PageHead(page) && !PMDPageInPUD(page), page);
} else if (thp_migration_supported()) {
swp_entry_t entry;

@@ -2082,8 +2082,16 @@ int zap_huge_pud(struct mmu_gather *tlb, struct vm_area_struct *vma,
}

static void __split_huge_pud_locked(struct vm_area_struct *vma, pud_t *pud,
- unsigned long haddr)
+ unsigned long haddr, bool freeze)
{
+ struct mm_struct *mm = vma->vm_mm;
+ struct page *page;
+ pgtable_t pgtable;
+ pud_t _pud, old_pud;
+ bool young, write, dirty, soft_dirty;
+ unsigned long addr;
+ int i;
+
VM_BUG_ON(haddr & ~HPAGE_PUD_MASK);
VM_BUG_ON_VMA(vma->vm_start > haddr, vma);
VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PUD_SIZE, vma);
@@ -2091,23 +2099,141 @@ static void __split_huge_pud_locked(struct vm_area_struct *vma, pud_t *pud,

count_vm_event(THP_SPLIT_PUD);

- pudp_huge_clear_flush_notify(vma, haddr, pud);
+ if (!vma_is_anonymous(vma)) {
+ _pud = pudp_huge_clear_flush_notify(vma, haddr, pud);
+ /*
+ * We are going to unmap this huge page. So
+ * just go ahead and zap it
+ */
+ if (arch_needs_pgtable_deposit())
+ zap_pud_deposited_table(mm, pud);
+ if (vma_is_dax(vma))
+ return;
+ page = pud_page(_pud);
+ if (!PageReferenced(page) && pud_young(_pud))
+ SetPageReferenced(page);
+ page_remove_rmap(page, HPAGE_PUD_ORDER);
+ put_page(page);
+ add_mm_counter(mm, MM_FILEPAGES, -HPAGE_PUD_NR);
+ return;
+ }
+
+ /* See the comment above pmdp_invalidate() in __split_huge_pmd_locked() */
+ old_pud = pudp_invalidate(vma, haddr, pud);
+
+ page = pud_page(old_pud);
+ VM_BUG_ON_PAGE(!page_count(page), page);
+ page_ref_add(page, (1<<(HPAGE_PUD_ORDER-HPAGE_PMD_ORDER)) - 1);
+ if (pud_dirty(old_pud))
+ SetPageDirty(page);
+ write = pud_write(old_pud);
+ young = pud_young(old_pud);
+ dirty = pud_dirty(old_pud);
+ soft_dirty = pud_soft_dirty(old_pud);
+
+ pgtable = pgtable_trans_huge_pud_withdraw(mm, pud);
+ pud_populate_with_pgtable(mm, &_pud, pgtable);
+
+ for (i = 0, addr = haddr; i < HPAGE_PUD_NR;
+ i += HPAGE_PMD_NR, addr += PMD_SIZE) {
+ pmd_t entry, *pmd;
+ /*
+ * Note that NUMA hinting access restrictions are not
+ * transferred to avoid any possibility of altering
+ * permissions across VMAs.
+ */
+ if (freeze) {
+ swp_entry_t swp_entry;
+
+ swp_entry = make_migration_entry(page + i, write);
+ entry = swp_entry_to_pmd(swp_entry);
+ if (soft_dirty)
+ entry = pmd_swp_mksoft_dirty(entry);
+ } else {
+ entry = mk_huge_pmd(page + i, READ_ONCE(vma->vm_page_prot));
+ entry = maybe_pmd_mkwrite(entry, vma);
+ if (!write)
+ entry = pmd_wrprotect(entry);
+ if (!young)
+ entry = pmd_mkold(entry);
+ if (soft_dirty)
+ entry = pmd_mksoft_dirty(entry);
+ }
+ pmd = pmd_offset(&_pud, addr);
+ VM_BUG_ON(!pmd_none(*pmd));
+ set_pmd_at(mm, addr, pmd, entry);
+ /* distinguish between pud compound_mapcount and pmd compound_mapcount */
+ if (atomic_inc_and_test(sub_compound_mapcount_ptr(&page[i], 1))) {
+ /* first pmd-mapped pud page */
+ lock_page_memcg(page);
+ __inc_lruvec_page_state(page, NR_ANON_THPS);
+ unlock_page_memcg(page);
+ }
+ }
+
+ /*
+ * Set PG_double_map before dropping compound_mapcount to avoid
+ * false-negative page_mapped().
+ */
+ if (compound_mapcount(page) > 1 && !TestSetPagePUDDoubleMap(page)) {
+ for (i = 0; i < HPAGE_PUD_NR; i += HPAGE_PMD_NR)
+ /* distinguish between pud compound_mapcount and pmd compound_mapcount */
+ atomic_inc(sub_compound_mapcount_ptr(&page[i], 1));
+ }
+
+ lock_page_memcg(page);
+ if (atomic_add_negative(-1, compound_mapcount_ptr(page))) {
+ /* Last compound_mapcount is gone. */
+ __dec_lruvec_page_state(page, NR_ANON_THPS_PUD);
+ if (TestClearPagePUDDoubleMap(page)) {
+ /* No need in mapcount reference anymore */
+ for (i = 0; i < HPAGE_PUD_NR; i += HPAGE_PMD_NR)
+ /* distinguish between pud compound_mapcount and pmd compound_mapcount */
+ atomic_dec(sub_compound_mapcount_ptr(&page[i], 1));
+ }
+ }
+ unlock_page_memcg(page);
+
+ smp_wmb(); /* make pte visible before pmd */
+ pud_populate_with_pgtable(mm, pud, pgtable);
+
+ if (freeze) {
+ for (i = 0; i < HPAGE_PUD_NR; i += HPAGE_PMD_NR) {
+ page_remove_rmap(page + i, HPAGE_PMD_ORDER);
+ put_page(page + i);
+ }
+ }
}

void __split_huge_pud(struct vm_area_struct *vma, pud_t *pud,
- unsigned long address)
+ unsigned long address, bool freeze, struct page *page)
{
spinlock_t *ptl;
+ struct mm_struct *mm = vma->vm_mm;
+ unsigned long haddr = address & HPAGE_PUD_MASK;
struct mmu_notifier_range range;

mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm,
address & HPAGE_PUD_MASK,
(address & HPAGE_PUD_MASK) + HPAGE_PUD_SIZE);
mmu_notifier_invalidate_range_start(&range);
- ptl = pud_lock(vma->vm_mm, pud);
- if (unlikely(!pud_trans_huge(*pud) && !pud_devmap(*pud)))
+ ptl = pud_lock(mm, pud);
+
+ /*
+ * If caller asks to setup a migration entries, we need a page to check
+ * pmd against. Otherwise we can end up replacing wrong page.
+ */
+ VM_BUG_ON(freeze && !page);
+ if (page && page != pud_page(*pud))
+ goto out;
+
+ if (pud_trans_huge(*pud)) {
+ page = pud_page(*pud);
+ if (PageMlocked(page))
+ clear_page_mlock(page);
+ } else if (unlikely(!pud_devmap(*pud)))
goto out;
- __split_huge_pud_locked(vma, pud, range.start);
+ __split_huge_pud_locked(vma, pud, haddr, freeze);

out:
spin_unlock(ptl);
@@ -2117,6 +2243,280 @@ void __split_huge_pud(struct vm_area_struct *vma, pud_t *pud,
*/
mmu_notifier_invalidate_range_only_end(&range);
}
+
+void split_huge_pud_address(struct vm_area_struct *vma, unsigned long address,
+ bool freeze, struct page *page)
+{
+ pgd_t *pgd;
+ p4d_t *p4d;
+ pud_t *pud;
+
+ pgd = pgd_offset(vma->vm_mm, address);
+ if (!pgd_present(*pgd))
+ return;
+
+ p4d = p4d_offset(pgd, address);
+ if (!p4d_present(*p4d))
+ return;
+
+ pud = pud_offset(p4d, address);
+
+ __split_huge_pud(vma, pud, address, freeze, page);
+}
+
+static void unmap_pud_page(struct page *page)
+{
+ enum ttu_flags ttu_flags = TTU_IGNORE_MLOCK | TTU_IGNORE_ACCESS |
+ TTU_RMAP_LOCKED | TTU_SPLIT_HUGE_PUD;
+ bool unmap_success;
+
+ VM_BUG_ON_PAGE(!PageHead(page), page);
+
+ if (PageAnon(page))
+ ttu_flags |= TTU_SPLIT_FREEZE;
+
+ unmap_success = try_to_unmap(page, ttu_flags);
+ VM_BUG_ON_PAGE(!unmap_success, page);
+}
+
+static void remap_pud_page(struct page *page)
+{
+ int i;
+
+ VM_BUG_ON(!PageTransHuge(page));
+ if (compound_order(page) == HPAGE_PUD_ORDER) {
+ remove_migration_ptes(page, page, true);
+ } else if (compound_order(page) == HPAGE_PMD_ORDER) {
+ for (i = 0; i < HPAGE_PUD_NR; i += HPAGE_PMD_NR)
+ remove_migration_ptes(page + i, page + i, true);
+ } else
+ VM_BUG_ON_PAGE(1, page);
+}
+
+static void __split_huge_pud_page_tail(struct page *head, int tail,
+ struct lruvec *lruvec, struct list_head *list)
+{
+ struct page *page_tail = head + tail;
+
+ VM_BUG_ON_PAGE(page_ref_count(page_tail) != 0, page_tail);
+
+ /*
+ * Clone page flags before unfreezing refcount.
+ *
+ * After successful get_page_unless_zero() might follow flags change,
+ * for example lock_page() which set PG_waiters.
+ */
+
+ page_tail->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
+ page_tail->flags |= (head->flags &
+ ((1L << PG_referenced) |
+ (1L << PG_swapbacked) |
+ (1L << PG_swapcache) |
+ (1L << PG_mlocked) |
+ (1L << PG_uptodate) |
+ (1L << PG_active) |
+ (1L << PG_locked) |
+ (1L << PG_unevictable) |
+ (1L << PG_dirty) |
+ /* preserve THP */
+ (1L << PG_head)));
+
+ /* ->mapping in first tail page is compound_mapcount */
+ VM_BUG_ON_PAGE(tail > 2 && page_tail->mapping != TAIL_MAPPING,
+ page_tail);
+ page_tail->mapping = head->mapping;
+ page_tail->index = head->index + tail;
+
+ /* Page flags also must be visible before we make the page PMD-compound. */
+ smp_wmb();
+
+ clear_compound_head(page_tail);
+ prep_compound_page(page_tail, HPAGE_PMD_ORDER);
+ prep_transhuge_page(page_tail);
+
+ /* Finally unfreeze refcount. Additional reference from page cache. */
+ page_ref_unfreeze(page_tail, 1 + (!PageAnon(head) ||
+ PageSwapCache(head)));
+
+ if (page_is_young(head))
+ set_page_young(page_tail);
+ if (page_is_idle(head))
+ set_page_idle(page_tail);
+
+ page_cpupid_xchg_last(page_tail, page_cpupid_last(head));
+ lru_add_pud_page_tail(head, page_tail, lruvec, list);
+}
+
+static void __split_huge_pud_page(struct page *page, struct list_head *list,
+ unsigned long flags)
+{
+ struct page *head = compound_head(page);
+ pg_data_t *pgdat = page_pgdat(head);
+ struct lruvec *lruvec;
+ int i;
+
+ lruvec = mem_cgroup_page_lruvec(head, pgdat);
+
+ /* complete memcg works before add pages to LRU */
+ mem_cgroup_split_huge_pud_fixup(head);
+
+ /* no file-back page support yet */
+ VM_BUG_ON(!PageAnon(page));
+
+ for (i = HPAGE_PUD_NR - HPAGE_PMD_NR; i >= 1; i -= HPAGE_PMD_NR)
+ __split_huge_pud_page_tail(head, i, lruvec, list);
+
+ /* reset head page order */
+ prep_compound_page(head, HPAGE_PMD_ORDER);
+ prep_transhuge_page(head);
+
+ page_ref_inc(head);
+
+ spin_unlock_irqrestore(&pgdat->lru_lock, flags);
+
+ remap_pud_page(head);
+
+ for (i = 0; i < HPAGE_PUD_NR; i += HPAGE_PMD_NR) {
+ struct page *subpage = head + i;
+
+ if (subpage == page)
+ continue;
+ unlock_page(subpage);
+
+ /*
+ * Subpages may be freed if there wasn't any mapping
+ * like if add_to_swap() is running on a lru page that
+ * had its mapping zapped. And freeing these pages
+ * requires taking the lru_lock so we do the put_page
+ * of the tail pages after the split is complete.
+ */
+ put_page(subpage);
+ }
+}
+/* Racy check whether the huge page can be split */
+bool can_split_huge_pud_page(struct page *page, int *pextra_pins)
+{
+ int extra_pins;
+
+ VM_BUG_ON(!PageAnon(page));
+
+ extra_pins = PageSwapCache(page) ? HPAGE_PUD_NR : 0;
+
+ if (pextra_pins)
+ *pextra_pins = extra_pins;
+ return total_mapcount(page) == page_count(page) - extra_pins - 1;
+}
+
+/*
+ * This function splits huge page into normal pages. @page can point to any
+ * subpage of huge page to split. Split doesn't change the position of @page.
+ *
+ * Only caller must hold pin on the @page, otherwise split fails with -EBUSY.
+ * The huge page must be locked.
+ *
+ * If @list is null, tail pages will be added to LRU list, otherwise, to @list.
+ *
+ * Both head page and tail pages will inherit mapping, flags, and so on from
+ * the hugepage.
+ *
+ * GUP pin and PG_locked transferred to @page. Rest subpages can be freed if
+ * they are not mapped.
+ *
+ * Returns 0 if the hugepage is split successfully.
+ * Returns -EBUSY if the page is pinned or if anon_vma disappeared from under
+ * us.
+ */
+int split_huge_pud_page_to_list(struct page *page, struct list_head *list)
+{
+ struct page *head = compound_head(page);
+ struct pglist_data *pgdata = NODE_DATA(page_to_nid(head));
+ struct deferred_split *ds_queue = get_deferred_split_queue(head);
+ struct anon_vma *anon_vma = NULL;
+ struct address_space *mapping = NULL;
+ int count, mapcount, extra_pins, ret;
+ bool mlocked;
+ unsigned long flags;
+
+ VM_BUG_ON_PAGE(is_huge_zero_page(page), page);
+ VM_BUG_ON_PAGE(!PageLocked(page), page);
+ VM_BUG_ON_PAGE(!PageCompound(page), page);
+ VM_BUG_ON_PAGE(!PageAnon(page), page);
+
+ if (PageWriteback(page))
+ return -EBUSY;
+
+ /*
+ * The caller does not necessarily hold an mmap_sem that would
+ * prevent the anon_vma disappearing so we first we take a
+ * reference to it and then lock the anon_vma for write. This
+ * is similar to page_lock_anon_vma_read except the write lock
+ * is taken to serialise against parallel split or collapse
+ * operations.
+ */
+ anon_vma = page_get_anon_vma(head);
+ if (!anon_vma) {
+ ret = -EBUSY;
+ goto out;
+ }
+ mapping = NULL;
+ anon_vma_lock_write(anon_vma);
+ /*
+ * Racy check if we can split the page, before unmap_pud_page() will
+ * split PUDs
+ */
+ if (!can_split_huge_pud_page(head, &extra_pins)) {
+ ret = -EBUSY;
+ goto out_unlock;
+ }
+
+ mlocked = PageMlocked(page);
+ unmap_pud_page(head);
+ VM_BUG_ON_PAGE(compound_mapcount(head), head);
+
+ /* Make sure the page is not on per-CPU pagevec as it takes pin */
+ if (mlocked)
+ lru_add_drain();
+
+ /* prevent PageLRU to go away from under us, and freeze lru stats */
+ spin_lock_irqsave(&pgdata->lru_lock, flags);
+
+ /* Prevent deferred_split_scan() touching ->_refcount */
+ spin_lock(&ds_queue->split_queue_lock);
+ count = page_count(head);
+ mapcount = total_mapcount(head);
+ 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));
+ }
+ if (mapping)
+ __dec_node_page_state(page, NR_SHMEM_THPS);
+ spin_unlock(&ds_queue->split_queue_lock);
+ __split_huge_pud_page(page, list, flags);
+ ret = 0;
+ } else {
+ if (IS_ENABLED(CONFIG_DEBUG_VM) && mapcount) {
+ pr_alert("total_mapcount: %u, page_count(): %u\n",
+ mapcount, count);
+ if (PageTail(page))
+ dump_page(head, NULL);
+ dump_page(page, "total_mapcount(head) > 0");
+ }
+ spin_unlock(&ds_queue->split_queue_lock);
+ spin_unlock_irqrestore(&pgdata->lru_lock, flags);
+ remap_pud_page(head);
+ ret = -EBUSY;
+ }
+
+out_unlock:
+ if (anon_vma) {
+ anon_vma_unlock_write(anon_vma);
+ put_anon_vma(anon_vma);
+ }
+out:
+ count_vm_event(!ret ? THP_SPLIT_PUD_PAGE : THP_SPLIT_PUD_PAGE_FAILED);
+ return ret;
+}
#endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */

static void __split_huge_zero_page_pmd(struct vm_area_struct *vma,
@@ -2157,7 +2557,7 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd,
unsigned long haddr, bool freeze)
{
struct mm_struct *mm = vma->vm_mm;
- struct page *page;
+ struct page *page, *head;
pgtable_t pgtable;
pmd_t old_pmd, _pmd;
bool young, write, soft_dirty, pmd_migration = false, uffd_wp = false;
@@ -2246,7 +2646,8 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd,
uffd_wp = pmd_uffd_wp(old_pmd);
}
VM_BUG_ON_PAGE(!page_count(page), page);
- page_ref_add(page, HPAGE_PMD_NR - 1);
+ head = compound_head(page);
+ page_ref_add(head, HPAGE_PMD_NR - 1);

/*
* Withdraw the table only after we mark the pmd entry invalid.
@@ -2294,15 +2695,25 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd,
/*
* Set PG_double_map before dropping compound_mapcount to avoid
* false-negative page_mapped().
+ * Don't set it if the PUD page is mapped at PUD level, since
+ * page_mapped() is true in that case.
*/
- if (compound_mapcount(page) > 1 &&
- !TestSetPageDoubleMap(page)) {
+ if (((PMDPageInPUD(page) &&
+ sub_compound_mapcount(page) >
+ (1 + PagePUDDoubleMap(compound_head(page)))) ||
+ (!PMDPageInPUD(page) &&
+ compound_mapcount(page) > 1))
+ && !TestSetPageDoubleMap(page)) {
for (i = 0; i < HPAGE_PMD_NR; i++)
atomic_inc(&page[i]._mapcount);
}

lock_page_memcg(page);
- if (atomic_add_negative(-1, compound_mapcount_ptr(page))) {
+
+ if ((PMDPageInPUD(page) &&
+ atomic_add_negative(-1, sub_compound_mapcount_ptr(page, 1))) ||
+ (!PMDPageInPUD(page) &&
+ atomic_add_negative(-1, compound_mapcount_ptr(page)))) {
/* Last compound_mapcount is gone. */
__dec_lruvec_page_state(page, NR_ANON_THPS);
if (TestClearPageDoubleMap(page)) {
@@ -2430,6 +2841,11 @@ void vma_adjust_trans_huge(struct vm_area_struct *vma,
* previously contain an hugepage: check if we need to split
* an huge pmd.
*/
+ if (start & ~HPAGE_PUD_MASK &&
+ (start & HPAGE_PUD_MASK) >= vma->vm_start &&
+ (start & HPAGE_PUD_MASK) + HPAGE_PUD_SIZE <= vma->vm_end)
+ split_huge_pud_address(vma, start, false, NULL);
+
if (start & ~HPAGE_PMD_MASK &&
(start & HPAGE_PMD_MASK) >= vma->vm_start &&
(start & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end)
@@ -2440,6 +2856,11 @@ void vma_adjust_trans_huge(struct vm_area_struct *vma,
* previously contain an hugepage: check if we need to split
* an huge pmd.
*/
+ if (end & ~HPAGE_PUD_MASK &&
+ (end & HPAGE_PUD_MASK) >= vma->vm_start &&
+ (end & HPAGE_PUD_MASK) + HPAGE_PUD_SIZE <= vma->vm_end)
+ split_huge_pud_address(vma, end, false, NULL);
+
if (end & ~HPAGE_PMD_MASK &&
(end & HPAGE_PMD_MASK) >= vma->vm_start &&
(end & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end)
@@ -2454,6 +2875,11 @@ void vma_adjust_trans_huge(struct vm_area_struct *vma,
struct vm_area_struct *next = vma->vm_next;
unsigned long nstart = next->vm_start;
nstart += adjust_next;
+ if (nstart & ~HPAGE_PUD_MASK &&
+ (nstart & HPAGE_PUD_MASK) >= next->vm_start &&
+ (nstart & HPAGE_PUD_MASK) + HPAGE_PUD_SIZE <= next->vm_end)
+ split_huge_pud_address(next, nstart, false, NULL);
+
if (nstart & ~HPAGE_PMD_MASK &&
(nstart & HPAGE_PMD_MASK) >= next->vm_start &&
(nstart & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= next->vm_end)
@@ -2645,12 +3071,23 @@ int total_mapcount(struct page *page)
if (PageHuge(page))
return compound;
ret = compound;
- for (i = 0; i < nr; i++)
- ret += atomic_read(&page[i]._mapcount) + 1;
+ /* if PMD, read all base page, if PUD, read the sub_compound_mapcount()*/
+ if (compound_order(page) == HPAGE_PMD_ORDER) {
+ for (i = 0; i < nr; i++)
+ ret += atomic_read(&page[i]._mapcount) + 1;
+ } else if (compound_order(page) == HPAGE_PUD_ORDER) {
+ for (i = 0; i < HPAGE_PUD_NR; i += HPAGE_PMD_NR)
+ ret += sub_compound_mapcount(&page[i]);
+ for (i = 0; i < nr; i++)
+ ret += atomic_read(&page[i]._mapcount) + 1;
+ /* both PUD and PMD has HPAGE_PMD_NR sub pages */
+ nr = HPAGE_PMD_NR;
+ } else
+ VM_BUG_ON_PAGE(1, page);
/* File pages has compound_mapcount included in _mapcount */
if (!PageAnon(page))
return ret - compound * nr;
- if (PageDoubleMap(page))
+ if (PagePUDDoubleMap(page) || PageDoubleMap(page))
ret -= nr;
return ret;
}
@@ -2681,7 +3118,7 @@ int total_mapcount(struct page *page)
*/
int page_trans_huge_mapcount(struct page *page, int *total_mapcount)
{
- int i, ret, _total_mapcount, mapcount;
+ int i, ret, _total_mapcount, mapcount, nr;

/* hugetlbfs shouldn't call it */
VM_BUG_ON_PAGE(PageHuge(page), page);
@@ -2696,14 +3133,41 @@ int page_trans_huge_mapcount(struct page *page, int *total_mapcount)
page = compound_head(page);

_total_mapcount = ret = 0;
- for (i = 0; i < thp_nr_pages(page); i++) {
- mapcount = atomic_read(&page[i]._mapcount) + 1;
- ret = max(ret, mapcount);
- _total_mapcount += mapcount;
- }
- if (PageDoubleMap(page)) {
+ nr = thp_nr_pages(page);
+ /* if PMD, read all base page, if PUD, read the sub_compound_mapcount()*/
+ if (compound_order(page) == HPAGE_PMD_ORDER) {
+ for (i = 0; i < nr; i++) {
+ mapcount = atomic_read(&page[i]._mapcount) + 1;
+ ret = max(ret, mapcount);
+ _total_mapcount += mapcount;
+ }
+ } else if (compound_order(page) == HPAGE_PUD_ORDER) {
+ for (i = 0; i < nr; i += HPAGE_PMD_NR) {
+ int j;
+
+ mapcount = sub_compound_mapcount(&page[i]);
+ ret = max(ret, mapcount);
+ _total_mapcount += mapcount;
+
+ /* Triple mapped at base page size */
+ for (j = 0; j < HPAGE_PMD_NR; j++) {
+ mapcount = atomic_read(&page[i + j]._mapcount) + 1;
+ ret = max(ret, mapcount);
+ _total_mapcount += mapcount;
+ }
+
+ if (PageDoubleMap(&page[i])) {
+ ret -= 1;
+ _total_mapcount -= HPAGE_PMD_NR;
+ }
+ }
+ /* both PUD and PMD has HPAGE_PMD_NR sub pages */
+ nr = HPAGE_PMD_NR;
+ } else
+ VM_BUG_ON_PAGE(1, page);
+ if (PageDoubleMap(page) || PagePUDDoubleMap(page)) {
ret -= 1;
- _total_mapcount -= thp_nr_pages(page);
+ _total_mapcount -= nr;
}
mapcount = compound_mapcount(page);
ret += mapcount;
@@ -2948,6 +3412,9 @@ static unsigned long deferred_split_count(struct shrinker *shrink,
return READ_ONCE(ds_queue->split_queue_len);
}

+#define deferred_list_entry(x) (compound_head(list_entry((void *)x, \
+ struct page, mapping)))
+
static unsigned long deferred_split_scan(struct shrinker *shrink,
struct shrink_control *sc)
{
@@ -2981,12 +3448,18 @@ static unsigned long deferred_split_scan(struct shrinker *shrink,
spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags);

list_for_each_safe(pos, next, &list) {
- page = list_entry((void *)pos, struct page, mapping);
+ page = deferred_list_entry(pos);
if (!trylock_page(page))
goto next;
/* split_huge_page() removes page from list on success */
- if (!split_huge_page(page))
- split++;
+ if (compound_order(page) == HPAGE_PUD_ORDER) {
+ if (!split_huge_pud_page(page))
+ split++;
+ } else if (compound_order(page) == HPAGE_PMD_ORDER) {
+ if (!split_huge_page(page))
+ split++;
+ } else
+ VM_BUG_ON_PAGE(1, page);
unlock_page(page);
next:
put_page(page);
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index b28f620c1c5b..ed75ef95b24a 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -3281,6 +3281,19 @@ void mem_cgroup_split_huge_fixup(struct page *head)
head[i].mem_cgroup = memcg;
}
}
+
+void mem_cgroup_split_huge_pud_fixup(struct page *head)
+{
+ int i;
+
+ if (mem_cgroup_disabled())
+ return;
+
+ for (i = HPAGE_PMD_NR; i < HPAGE_PUD_NR; i += HPAGE_PMD_NR)
+ head[i].mem_cgroup = head->mem_cgroup;
+
+ /*__mod_memcg_state(head->mem_cgroup, MEMCG_RSS_HUGE, -HPAGE_PUD_NR);*/
+}
#endif /* CONFIG_TRANSPARENT_HUGEPAGE */

#ifdef CONFIG_MEMCG_SWAP
diff --git a/mm/memory.c b/mm/memory.c
index 37e206a7d213..e0e0459c0caf 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -4133,7 +4133,7 @@ static vm_fault_t create_huge_pud(struct vm_fault *vmf)
}
split:
/* COW or write-notify not handled on PUD level: split pud.*/
- __split_huge_pud(vmf->vma, vmf->pud, vmf->address);
+ __split_huge_pud(vmf->vma, vmf->pud, vmf->address, false, NULL);
#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
return VM_FAULT_FALLBACK;
}
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 29abeff09fcc..6bdb38a8fb48 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -679,6 +679,9 @@ void prep_compound_page(struct page *page, unsigned int order)
atomic_set(compound_mapcount_ptr(page), -1);
if (hpage_pincount_available(page))
atomic_set(compound_pincount_ptr(page), 0);
+ if (order == HPAGE_PUD_ORDER)
+ for (i = 0; i < HPAGE_PUD_NR; i += HPAGE_PMD_NR)
+ atomic_set(sub_compound_mapcount_ptr(&page[i], 1), -1);
}

#ifdef CONFIG_DEBUG_PAGEALLOC
@@ -1132,6 +1135,16 @@ static int free_tail_pages_check(struct page *head_page, struct page *page)
*/
break;
default:
+ /* sub_compound_map_ptr store here */
+ if (compound_order(head_page) == HPAGE_PUD_ORDER &&
+ (page - head_page) % HPAGE_PMD_NR == 3) {
+ if (unlikely(atomic_read(&page->compound_mapcount) != -1)) {
+ pr_err("sub_compound_mapcount: %d\n",
+ atomic_read(&page->compound_mapcount) + 1);
+ bad_page(page, "nonzero sub_compound_mapcount");
+ }
+ break;
+ }
if (page->mapping != TAIL_MAPPING) {
bad_page(page, "corrupted mapping in tail page");
goto out;
@@ -1183,8 +1196,14 @@ static __always_inline bool free_pages_prepare(struct page *page,

VM_BUG_ON_PAGE(compound && compound_order(page) != order, page);

- if (compound)
+ if (compound) {
ClearPageDoubleMap(page);
+ if (order == HPAGE_PUD_ORDER) {
+ ClearPagePUDDoubleMap(page);
+ for (i = 0; i < HPAGE_PUD_NR; i += HPAGE_PMD_NR)
+ ClearPageDoubleMap(&page[i]);
+ }
+ }
for (i = 1; i < (1 << order); i++) {
if (compound)
bad += free_tail_pages_check(page, page + i);
diff --git a/mm/pagewalk.c b/mm/pagewalk.c
index a3752c82a7b2..c190140637c9 100644
--- a/mm/pagewalk.c
+++ b/mm/pagewalk.c
@@ -160,7 +160,7 @@ static int walk_pud_range(p4d_t *p4d, unsigned long addr, unsigned long end,
if (walk->vma) {
split_huge_pud(walk->vma, pudp, addr);
pud = READ_ONCE(*pudp);
- if (pud_none(pud))
+ if (pud_trans_unstable(&pud))
goto again;
}

diff --git a/mm/pgtable-generic.c b/mm/pgtable-generic.c
index a014cf847067..2b83dd4807e5 100644
--- a/mm/pgtable-generic.c
+++ b/mm/pgtable-generic.c
@@ -218,6 +218,17 @@ pmd_t pmdp_invalidate(struct vm_area_struct *vma, unsigned long address,
}
#endif

+#ifndef __HAVE_ARCH_PUDP_INVALIDATE
+pud_t pudp_invalidate(struct vm_area_struct *vma, unsigned long address,
+ pud_t *pudp)
+{
+ pud_t old = pudp_establish(vma, address, pudp, pud_mknotpresent(*pudp));
+
+ flush_pud_tlb_range(vma, address, address + HPAGE_PUD_SIZE);
+ return old;
+}
+#endif
+
#ifndef pmdp_collapse_flush
pmd_t pmdp_collapse_flush(struct vm_area_struct *vma, unsigned long address,
pmd_t *pmdp)
diff --git a/mm/rmap.c b/mm/rmap.c
index 7fc0bf07b9bc..b4950f7a0978 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1132,10 +1132,21 @@ void do_page_add_anon_rmap(struct page *page,
VM_BUG_ON_PAGE(!PageLocked(page), page);

if (compound) {
- atomic_t *mapcount;
+ atomic_t *mapcount = NULL;
VM_BUG_ON_PAGE(!PageLocked(page), page);
VM_BUG_ON_PAGE(!PageTransHuge(page), page);
- mapcount = compound_mapcount_ptr(page);
+ if (compound_order(page) == HPAGE_PUD_ORDER) {
+ if (map_order == HPAGE_PUD_ORDER) {
+ mapcount = compound_mapcount_ptr(page);
+ } else if (map_order == HPAGE_PMD_ORDER) {
+ VM_BUG_ON(!PMDPageInPUD(page));
+ mapcount = sub_compound_mapcount_ptr(page, 1);
+ } else
+ VM_BUG_ON(1);
+ } else if (compound_order(page) == HPAGE_PMD_ORDER) {
+ mapcount = compound_mapcount_ptr(page);
+ } else
+ VM_BUG_ON(1);
first = atomic_inc_and_test(mapcount);
} else {
first = atomic_inc_and_test(&page->_mapcount);
@@ -1150,7 +1161,7 @@ void do_page_add_anon_rmap(struct page *page,
* disabled.
*/
if (compound) {
- if (nr == HPAGE_PMD_NR)
+ if (map_order == HPAGE_PMD_ORDER)
__inc_lruvec_page_state(page, NR_ANON_THPS);
else
__inc_lruvec_page_state(page, NR_ANON_THPS_PUD);
@@ -1197,10 +1208,15 @@ void page_add_new_anon_rmap(struct page *page,
if (hpage_pincount_available(page))
atomic_set(compound_pincount_ptr(page), 0);

- if (nr == HPAGE_PMD_NR)
- __inc_lruvec_page_state(page, NR_ANON_THPS);
- else
+ if (map_order == HPAGE_PUD_ORDER) {
+ VM_BUG_ON(compound_order(page) != HPAGE_PUD_ORDER);
+ /* Anon THP always mapped first with PMD */
__inc_lruvec_page_state(page, NR_ANON_THPS_PUD);
+ } else if (map_order == HPAGE_PMD_ORDER) {
+ VM_BUG_ON(compound_order(page) != HPAGE_PMD_ORDER);
+ __inc_lruvec_page_state(page, NR_ANON_THPS);
+ } else
+ VM_BUG_ON(1);
} else {
/* Anon THP always mapped first with PMD */
VM_BUG_ON_PAGE(PageTransCompound(page), page);
@@ -1294,10 +1310,38 @@ static void page_remove_file_rmap(struct page *page, bool compound)

static void page_remove_anon_compound_rmap(struct page *page, int map_order)
{
- int i, nr;
+ int i, nr = 0;
+ struct page *head = compound_head(page);
+
+ if (compound_order(head) == HPAGE_PUD_ORDER) {
+ if (map_order == HPAGE_PMD_ORDER) {
+ VM_BUG_ON(!PMDPageInPUD(page));
+ if (atomic_add_negative(-1, sub_compound_mapcount_ptr(page, 1))) {
+ if (TestClearPageDoubleMap(page)) {
+ /*
+ * Subpages can be mapped with PTEs too. Check how many of
+ * themi are still mapped.
+ */
+ for (i = 0; i < thp_nr_pages(head); i++) {
+ if (atomic_add_negative(-1, &head[i]._mapcount))
+ nr++;
+ }
+ }
+ __dec_node_page_state(page, NR_ANON_THPS);
+ }
+ nr += HPAGE_PMD_NR;
+ __mod_node_page_state(page_pgdat(head), NR_ANON_MAPPED, -nr);
+ return;
+ }

- if (!atomic_add_negative(-1, compound_mapcount_ptr(page)))
- return;
+ VM_BUG_ON(map_order != HPAGE_PUD_ORDER);
+ if (!atomic_add_negative(-1, compound_mapcount_ptr(page)))
+ return;
+ } else if (compound_order(head) == HPAGE_PMD_ORDER) {
+ if (!atomic_add_negative(-1, compound_mapcount_ptr(page)))
+ return;
+ } else
+ VM_BUG_ON_PAGE(1, page);

/* Hugepages are not counted in NR_ANON_PAGES for now. */
if (unlikely(PageHuge(page)))
@@ -1308,10 +1352,31 @@ static void page_remove_anon_compound_rmap(struct page *page, int map_order)

if (map_order == HPAGE_PMD_ORDER)
__dec_lruvec_page_state(page, NR_ANON_THPS);
- else
+ else if (map_order == HPAGE_PUD_ORDER)
__dec_lruvec_page_state(page, NR_ANON_THPS_PUD);
+ else
+ VM_BUG_ON(1);

- if (TestClearPageDoubleMap(page)) {
+ /* PMD-mapped PUD THP is handled above */
+ if (TestClearPagePUDDoubleMap(head)) {
+ VM_BUG_ON(!(compound_order(head) == HPAGE_PUD_ORDER || head == page));
+ /*
+ * Subpages can be mapped with PMDs too. Check how many of
+ * them are still mapped.
+ */
+ for (i = 0, nr = 0; i < HPAGE_PUD_NR; i += HPAGE_PMD_NR) {
+ if (atomic_add_negative(-1, sub_compound_mapcount_ptr(&head[i], 1)))
+ nr += HPAGE_PMD_NR;
+ }
+ /*
+ * Queue the page for deferred split if at least one pmd page
+ * of the pud compound page is unmapped, but at least one
+ * pmd page is still mapped.
+ */
+ if (nr && nr < thp_nr_pages(head))
+ deferred_split_huge_page(head);
+ } else if (TestClearPageDoubleMap(head)) {
+ VM_BUG_ON(compound_order(head) != HPAGE_PMD_ORDER);
/*
* Subpages can be mapped with PTEs too. Check how many of
* them are still mapped.
@@ -1335,8 +1400,10 @@ static void page_remove_anon_compound_rmap(struct page *page, int map_order)
if (unlikely(PageMlocked(page)))
clear_page_mlock(page);

- if (nr)
- __mod_lruvec_page_state(page, NR_ANON_MAPPED, -nr);
+ if (nr) {
+ __mod_lruvec_page_state(head, NR_ANON_MAPPED, -nr);
+ deferred_split_huge_page(head);
+ }
}

/**
diff --git a/mm/swap.c b/mm/swap.c
index 7e79829a2e73..43c18e5b6916 100644
--- a/mm/swap.c
+++ b/mm/swap.c
@@ -1005,6 +1005,36 @@ void lru_add_page_tail(struct page *page, struct page *page_tail,
page_lru(page_tail));
}
}
+
+/* used by __split_pud_huge_page_tail() */
+void lru_add_pud_page_tail(struct page *page, struct page *page_tail,
+ struct lruvec *lruvec, struct list_head *list)
+{
+ VM_BUG_ON_PAGE(!PageHead(page), page);
+ VM_BUG_ON_PAGE(PageLRU(page_tail), page);
+ lockdep_assert_held(&lruvec_pgdat(lruvec)->lru_lock);
+
+ if (!list)
+ SetPageLRU(page_tail);
+
+ if (likely(PageLRU(page)))
+ list_add_tail(&page_tail->lru, &page->lru);
+ else if (list) {
+ /* page reclaim is reclaiming a huge page */
+ get_page(page_tail);
+ list_add_tail(&page_tail->lru, list);
+ } else {
+ /*
+ * Head page has not yet been counted, as an hpage,
+ * so we must account for each subpage individually.
+ *
+ * Put page_tail on the list at the correct position
+ * so they all end up in order.
+ */
+ add_page_to_lru_list_tail(page_tail, lruvec,
+ page_lru(page_tail));
+ }
+}
#endif /* CONFIG_TRANSPARENT_HUGEPAGE */

static void __pagevec_lru_add_fn(struct page *page, struct lruvec *lruvec,
diff --git a/mm/util.c b/mm/util.c
index bb902f5a6582..e22d04d9e020 100644
--- a/mm/util.c
+++ b/mm/util.c
@@ -653,6 +653,12 @@ bool page_mapped(struct page *page)
page = compound_head(page);
if (atomic_read(compound_mapcount_ptr(page)) >= 0)
return true;
+ if (compound_order(page) == HPAGE_PUD_ORDER) {
+ for (i = 0; i < HPAGE_PUD_NR; i += HPAGE_PMD_NR) {
+ if (sub_compound_mapcount(page + i) > 0)
+ return true;
+ }
+ }
if (PageHuge(page))
return false;
for (i = 0; i < compound_nr(page); i++) {
@@ -713,17 +719,27 @@ struct address_space *page_mapping_file(struct page *page)
int __page_mapcount(struct page *page)
{
int ret;
+ struct page *head = compound_head(page);

+ /* base page mapping */
ret = atomic_read(&page->_mapcount) + 1;
+
+ /* PMDInPUD mapping */
+ if (compound_order(head) == HPAGE_PUD_ORDER) {
+ struct page *sub_compound_page = head +
+ (((page - head) / HPAGE_PMD_NR) * HPAGE_PMD_NR);
+
+ ret += sub_compound_mapcount(sub_compound_page);
+ }
/*
* For file THP page->_mapcount contains total number of mapping
* of the page: no need to look into compound_mapcount.
*/
if (!PageAnon(page) && !PageHuge(page))
return ret;
- page = compound_head(page);
- ret += atomic_read(compound_mapcount_ptr(page)) + 1;
- if (PageDoubleMap(page))
+ /* highest compound mapping */
+ ret += atomic_read(compound_mapcount_ptr(head)) + 1;
+ if (PageDoubleMap(head))
ret--;
return ret;
}
diff --git a/mm/vmstat.c b/mm/vmstat.c
index a9e50ef6a40d..2bb702d79f01 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -1331,6 +1331,10 @@ const char * const vmstat_text[] = {
"thp_fault_fallback_pud",
"thp_fault_fallback_pud_charge",
"thp_split_pud",
+ "thp_split_pud_page",
+ "thp_split_pud_page_failed",
+ "thp_zero_pud_page_alloc",
+ "thp_zero_pud_page_alloc_failed",
#endif
"thp_zero_page_alloc",
"thp_zero_page_alloc_failed",
--
2.28.0
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