--- /dev/null
+/*
+ * mm/rmap.c - physical to virtual reverse mappings
+ *
+ * Copyright 2001, Rik van Riel <riel@conectiva.com.br>
+ * Released under the General Public License (GPL).
+ *
+ * Simple, low overhead reverse mapping scheme.
+ * Please try to keep this thing as modular as possible.
+ *
+ * Provides methods for unmapping each kind of mapped page:
+ * the anon methods track anonymous pages, and
+ * the file methods track pages belonging to an inode.
+ *
+ * Original design by Rik van Riel <riel@conectiva.com.br> 2001
+ * File methods by Dave McCracken <dmccr@us.ibm.com> 2003, 2004
+ * Anonymous methods by Andrea Arcangeli <andrea@suse.de> 2004
+ * Contributions by Hugh Dickins 2003, 2004
+ */
+
+/*
+ * Lock ordering in mm:
+ *
+ * inode->i_mutex (while writing or truncating, not reading or faulting)
+ * mm->mmap_sem
+ * page->flags PG_locked (lock_page)
+ * mapping->i_mmap_rwsem
+ * anon_vma->rwsem
+ * mm->page_table_lock or pte_lock
+ * zone->lru_lock (in mark_page_accessed, isolate_lru_page)
+ * swap_lock (in swap_duplicate, swap_info_get)
+ * mmlist_lock (in mmput, drain_mmlist and others)
+ * mapping->private_lock (in __set_page_dirty_buffers)
+ * inode->i_lock (in set_page_dirty's __mark_inode_dirty)
+ * bdi.wb->list_lock (in set_page_dirty's __mark_inode_dirty)
+ * sb_lock (within inode_lock in fs/fs-writeback.c)
+ * mapping->tree_lock (widely used, in set_page_dirty,
+ * in arch-dependent flush_dcache_mmap_lock,
+ * within bdi.wb->list_lock in __sync_single_inode)
+ *
+ * anon_vma->rwsem,mapping->i_mutex (memory_failure, collect_procs_anon)
+ * ->tasklist_lock
+ * pte map lock
+ */
+
+#include <linux/mm.h>
+#include <linux/pagemap.h>
+#include <linux/swap.h>
+#include <linux/swapops.h>
+#include <linux/slab.h>
+#include <linux/init.h>
+#include <linux/ksm.h>
+#include <linux/rmap.h>
+#include <linux/rcupdate.h>
+#include <linux/export.h>
+#include <linux/memcontrol.h>
+#include <linux/mmu_notifier.h>
+#include <linux/migrate.h>
+#include <linux/hugetlb.h>
+#include <linux/backing-dev.h>
+
+#include <asm/tlbflush.h>
+
+#include "internal.h"
+
+static struct kmem_cache *anon_vma_cachep;
+static struct kmem_cache *anon_vma_chain_cachep;
+
+static inline struct anon_vma *anon_vma_alloc(void)
+{
+ struct anon_vma *anon_vma;
+
+ anon_vma = kmem_cache_alloc(anon_vma_cachep, GFP_KERNEL);
+ if (anon_vma) {
+ atomic_set(&anon_vma->refcount, 1);
+ anon_vma->degree = 1; /* Reference for first vma */
+ anon_vma->parent = anon_vma;
+ /*
+ * Initialise the anon_vma root to point to itself. If called
+ * from fork, the root will be reset to the parents anon_vma.
+ */
+ anon_vma->root = anon_vma;
+ }
+
+ return anon_vma;
+}
+
+static inline void anon_vma_free(struct anon_vma *anon_vma)
+{
+ VM_BUG_ON(atomic_read(&anon_vma->refcount));
+
+ /*
+ * Synchronize against page_lock_anon_vma_read() such that
+ * we can safely hold the lock without the anon_vma getting
+ * freed.
+ *
+ * Relies on the full mb implied by the atomic_dec_and_test() from
+ * put_anon_vma() against the acquire barrier implied by
+ * down_read_trylock() from page_lock_anon_vma_read(). This orders:
+ *
+ * page_lock_anon_vma_read() VS put_anon_vma()
+ * down_read_trylock() atomic_dec_and_test()
+ * LOCK MB
+ * atomic_read() rwsem_is_locked()
+ *
+ * LOCK should suffice since the actual taking of the lock must
+ * happen _before_ what follows.
+ */
+ might_sleep();
+ if (rwsem_is_locked(&anon_vma->root->rwsem)) {
+ anon_vma_lock_write(anon_vma);
+ anon_vma_unlock_write(anon_vma);
+ }
+
+ kmem_cache_free(anon_vma_cachep, anon_vma);
+}
+
+static inline struct anon_vma_chain *anon_vma_chain_alloc(gfp_t gfp)
+{
+ return kmem_cache_alloc(anon_vma_chain_cachep, gfp);
+}
+
+static void anon_vma_chain_free(struct anon_vma_chain *anon_vma_chain)
+{
+ kmem_cache_free(anon_vma_chain_cachep, anon_vma_chain);
+}
+
+static void anon_vma_chain_link(struct vm_area_struct *vma,
+ struct anon_vma_chain *avc,
+ struct anon_vma *anon_vma)
+{
+ avc->vma = vma;
+ avc->anon_vma = anon_vma;
+ list_add(&avc->same_vma, &vma->anon_vma_chain);
+ anon_vma_interval_tree_insert(avc, &anon_vma->rb_root);
+}
+
+/**
+ * anon_vma_prepare - attach an anon_vma to a memory region
+ * @vma: the memory region in question
+ *
+ * This makes sure the memory mapping described by 'vma' has
+ * an 'anon_vma' attached to it, so that we can associate the
+ * anonymous pages mapped into it with that anon_vma.
+ *
+ * The common case will be that we already have one, but if
+ * not we either need to find an adjacent mapping that we
+ * can re-use the anon_vma from (very common when the only
+ * reason for splitting a vma has been mprotect()), or we
+ * allocate a new one.
+ *
+ * Anon-vma allocations are very subtle, because we may have
+ * optimistically looked up an anon_vma in page_lock_anon_vma_read()
+ * and that may actually touch the spinlock even in the newly
+ * allocated vma (it depends on RCU to make sure that the
+ * anon_vma isn't actually destroyed).
+ *
+ * As a result, we need to do proper anon_vma locking even
+ * for the new allocation. At the same time, we do not want
+ * to do any locking for the common case of already having
+ * an anon_vma.
+ *
+ * This must be called with the mmap_sem held for reading.
+ */
+int anon_vma_prepare(struct vm_area_struct *vma)
+{
+ struct anon_vma *anon_vma = vma->anon_vma;
+ struct anon_vma_chain *avc;
+
+ might_sleep();
+ if (unlikely(!anon_vma)) {
+ struct mm_struct *mm = vma->vm_mm;
+ struct anon_vma *allocated;
+
+ avc = anon_vma_chain_alloc(GFP_KERNEL);
+ if (!avc)
+ goto out_enomem;
+
+ anon_vma = find_mergeable_anon_vma(vma);
+ allocated = NULL;
+ if (!anon_vma) {
+ anon_vma = anon_vma_alloc();
+ if (unlikely(!anon_vma))
+ goto out_enomem_free_avc;
+ allocated = anon_vma;
+ }
+
+ anon_vma_lock_write(anon_vma);
+ /* page_table_lock to protect against threads */
+ spin_lock(&mm->page_table_lock);
+ if (likely(!vma->anon_vma)) {
+ vma->anon_vma = anon_vma;
+ anon_vma_chain_link(vma, avc, anon_vma);
+ /* vma reference or self-parent link for new root */
+ anon_vma->degree++;
+ allocated = NULL;
+ avc = NULL;
+ }
+ spin_unlock(&mm->page_table_lock);
+ anon_vma_unlock_write(anon_vma);
+
+ if (unlikely(allocated))
+ put_anon_vma(allocated);
+ if (unlikely(avc))
+ anon_vma_chain_free(avc);
+ }
+ return 0;
+
+ out_enomem_free_avc:
+ anon_vma_chain_free(avc);
+ out_enomem:
+ return -ENOMEM;
+}
+
+/*
+ * This is a useful helper function for locking the anon_vma root as
+ * we traverse the vma->anon_vma_chain, looping over anon_vma's that
+ * have the same vma.
+ *
+ * Such anon_vma's should have the same root, so you'd expect to see
+ * just a single mutex_lock for the whole traversal.
+ */
+static inline struct anon_vma *lock_anon_vma_root(struct anon_vma *root, struct anon_vma *anon_vma)
+{
+ struct anon_vma *new_root = anon_vma->root;
+ if (new_root != root) {
+ if (WARN_ON_ONCE(root))
+ up_write(&root->rwsem);
+ root = new_root;
+ down_write(&root->rwsem);
+ }
+ return root;
+}
+
+static inline void unlock_anon_vma_root(struct anon_vma *root)
+{
+ if (root)
+ up_write(&root->rwsem);
+}
+
+/*
+ * Attach the anon_vmas from src to dst.
+ * Returns 0 on success, -ENOMEM on failure.
+ *
+ * If dst->anon_vma is NULL this function tries to find and reuse existing
+ * anon_vma which has no vmas and only one child anon_vma. This prevents
+ * degradation of anon_vma hierarchy to endless linear chain in case of
+ * constantly forking task. On the other hand, an anon_vma with more than one
+ * child isn't reused even if there was no alive vma, thus rmap walker has a
+ * good chance of avoiding scanning the whole hierarchy when it searches where
+ * page is mapped.
+ */
+int anon_vma_clone(struct vm_area_struct *dst, struct vm_area_struct *src)
+{
+ struct anon_vma_chain *avc, *pavc;
+ struct anon_vma *root = NULL;
+
+ list_for_each_entry_reverse(pavc, &src->anon_vma_chain, same_vma) {
+ struct anon_vma *anon_vma;
+
+ avc = anon_vma_chain_alloc(GFP_NOWAIT | __GFP_NOWARN);
+ if (unlikely(!avc)) {
+ unlock_anon_vma_root(root);
+ root = NULL;
+ avc = anon_vma_chain_alloc(GFP_KERNEL);
+ if (!avc)
+ goto enomem_failure;
+ }
+ anon_vma = pavc->anon_vma;
+ root = lock_anon_vma_root(root, anon_vma);
+ anon_vma_chain_link(dst, avc, anon_vma);
+
+ /*
+ * Reuse existing anon_vma if its degree lower than two,
+ * that means it has no vma and only one anon_vma child.
+ *
+ * Do not chose parent anon_vma, otherwise first child
+ * will always reuse it. Root anon_vma is never reused:
+ * it has self-parent reference and at least one child.
+ */
+ if (!dst->anon_vma && anon_vma != src->anon_vma &&
+ anon_vma->degree < 2)
+ dst->anon_vma = anon_vma;
+ }
+ if (dst->anon_vma)
+ dst->anon_vma->degree++;
+ unlock_anon_vma_root(root);
+ return 0;
+
+ enomem_failure:
+ /*
+ * dst->anon_vma is dropped here otherwise its degree can be incorrectly
+ * decremented in unlink_anon_vmas().
+ * We can safely do this because callers of anon_vma_clone() don't care
+ * about dst->anon_vma if anon_vma_clone() failed.
+ */
+ dst->anon_vma = NULL;
+ unlink_anon_vmas(dst);
+ return -ENOMEM;
+}
+
+/*
+ * Attach vma to its own anon_vma, as well as to the anon_vmas that
+ * the corresponding VMA in the parent process is attached to.
+ * Returns 0 on success, non-zero on failure.
+ */
+int anon_vma_fork(struct vm_area_struct *vma, struct vm_area_struct *pvma)
+{
+ struct anon_vma_chain *avc;
+ struct anon_vma *anon_vma;
+ int error;
+
+ /* Don't bother if the parent process has no anon_vma here. */
+ if (!pvma->anon_vma)
+ return 0;
+
+ /* Drop inherited anon_vma, we'll reuse existing or allocate new. */
+ vma->anon_vma = NULL;
+
+ /*
+ * First, attach the new VMA to the parent VMA's anon_vmas,
+ * so rmap can find non-COWed pages in child processes.
+ */
+ error = anon_vma_clone(vma, pvma);
+ if (error)
+ return error;
+
+ /* An existing anon_vma has been reused, all done then. */
+ if (vma->anon_vma)
+ return 0;
+
+ /* Then add our own anon_vma. */
+ anon_vma = anon_vma_alloc();
+ if (!anon_vma)
+ goto out_error;
+ avc = anon_vma_chain_alloc(GFP_KERNEL);
+ if (!avc)
+ goto out_error_free_anon_vma;
+
+ /*
+ * The root anon_vma's spinlock is the lock actually used when we
+ * lock any of the anon_vmas in this anon_vma tree.
+ */
+ anon_vma->root = pvma->anon_vma->root;
+ anon_vma->parent = pvma->anon_vma;
+ /*
+ * With refcounts, an anon_vma can stay around longer than the
+ * process it belongs to. The root anon_vma needs to be pinned until
+ * this anon_vma is freed, because the lock lives in the root.
+ */
+ get_anon_vma(anon_vma->root);
+ /* Mark this anon_vma as the one where our new (COWed) pages go. */
+ vma->anon_vma = anon_vma;
+ anon_vma_lock_write(anon_vma);
+ anon_vma_chain_link(vma, avc, anon_vma);
+ anon_vma->parent->degree++;
+ anon_vma_unlock_write(anon_vma);
+
+ return 0;
+
+ out_error_free_anon_vma:
+ put_anon_vma(anon_vma);
+ out_error:
+ unlink_anon_vmas(vma);
+ return -ENOMEM;
+}
+
+void unlink_anon_vmas(struct vm_area_struct *vma)
+{
+ struct anon_vma_chain *avc, *next;
+ struct anon_vma *root = NULL;
+
+ /*
+ * Unlink each anon_vma chained to the VMA. This list is ordered
+ * from newest to oldest, ensuring the root anon_vma gets freed last.
+ */
+ list_for_each_entry_safe(avc, next, &vma->anon_vma_chain, same_vma) {
+ struct anon_vma *anon_vma = avc->anon_vma;
+
+ root = lock_anon_vma_root(root, anon_vma);
+ anon_vma_interval_tree_remove(avc, &anon_vma->rb_root);
+
+ /*
+ * Leave empty anon_vmas on the list - we'll need
+ * to free them outside the lock.
+ */
+ if (RB_EMPTY_ROOT(&anon_vma->rb_root)) {
+ anon_vma->parent->degree--;
+ continue;
+ }
+
+ list_del(&avc->same_vma);
+ anon_vma_chain_free(avc);
+ }
+ if (vma->anon_vma)
+ vma->anon_vma->degree--;
+ unlock_anon_vma_root(root);
+
+ /*
+ * Iterate the list once more, it now only contains empty and unlinked
+ * anon_vmas, destroy them. Could not do before due to __put_anon_vma()
+ * needing to write-acquire the anon_vma->root->rwsem.
+ */
+ list_for_each_entry_safe(avc, next, &vma->anon_vma_chain, same_vma) {
+ struct anon_vma *anon_vma = avc->anon_vma;
+
+ BUG_ON(anon_vma->degree);
+ put_anon_vma(anon_vma);
+
+ list_del(&avc->same_vma);
+ anon_vma_chain_free(avc);
+ }
+}
+
+static void anon_vma_ctor(void *data)
+{
+ struct anon_vma *anon_vma = data;
+
+ init_rwsem(&anon_vma->rwsem);
+ atomic_set(&anon_vma->refcount, 0);
+ anon_vma->rb_root = RB_ROOT;
+}
+
+void __init anon_vma_init(void)
+{
+ anon_vma_cachep = kmem_cache_create("anon_vma", sizeof(struct anon_vma),
+ 0, SLAB_DESTROY_BY_RCU|SLAB_PANIC, anon_vma_ctor);
+ anon_vma_chain_cachep = KMEM_CACHE(anon_vma_chain, SLAB_PANIC);
+}
+
+/*
+ * Getting a lock on a stable anon_vma from a page off the LRU is tricky!
+ *
+ * Since there is no serialization what so ever against page_remove_rmap()
+ * the best this function can do is return a locked anon_vma that might
+ * have been relevant to this page.
+ *
+ * The page might have been remapped to a different anon_vma or the anon_vma
+ * returned may already be freed (and even reused).
+ *
+ * In case it was remapped to a different anon_vma, the new anon_vma will be a
+ * child of the old anon_vma, and the anon_vma lifetime rules will therefore
+ * ensure that any anon_vma obtained from the page will still be valid for as
+ * long as we observe page_mapped() [ hence all those page_mapped() tests ].
+ *
+ * All users of this function must be very careful when walking the anon_vma
+ * chain and verify that the page in question is indeed mapped in it
+ * [ something equivalent to page_mapped_in_vma() ].
+ *
+ * Since anon_vma's slab is DESTROY_BY_RCU and we know from page_remove_rmap()
+ * that the anon_vma pointer from page->mapping is valid if there is a
+ * mapcount, we can dereference the anon_vma after observing those.
+ */
+struct anon_vma *page_get_anon_vma(struct page *page)
+{
+ struct anon_vma *anon_vma = NULL;
+ unsigned long anon_mapping;
+
+ rcu_read_lock();
+ anon_mapping = (unsigned long)READ_ONCE(page->mapping);
+ if ((anon_mapping & PAGE_MAPPING_FLAGS) != PAGE_MAPPING_ANON)
+ goto out;
+ if (!page_mapped(page))
+ goto out;
+
+ anon_vma = (struct anon_vma *) (anon_mapping - PAGE_MAPPING_ANON);
+ if (!atomic_inc_not_zero(&anon_vma->refcount)) {
+ anon_vma = NULL;
+ goto out;
+ }
+
+ /*
+ * If this page is still mapped, then its anon_vma cannot have been
+ * freed. But if it has been unmapped, we have no security against the
+ * anon_vma structure being freed and reused (for another anon_vma:
+ * SLAB_DESTROY_BY_RCU guarantees that - so the atomic_inc_not_zero()
+ * above cannot corrupt).
+ */
+ if (!page_mapped(page)) {
+ rcu_read_unlock();
+ put_anon_vma(anon_vma);
+ return NULL;
+ }
+out:
+ rcu_read_unlock();
+
+ return anon_vma;
+}
+
+/*
+ * Similar to page_get_anon_vma() except it locks the anon_vma.
+ *
+ * Its a little more complex as it tries to keep the fast path to a single
+ * atomic op -- the trylock. If we fail the trylock, we fall back to getting a
+ * reference like with page_get_anon_vma() and then block on the mutex.
+ */
+struct anon_vma *page_lock_anon_vma_read(struct page *page)
+{
+ struct anon_vma *anon_vma = NULL;
+ struct anon_vma *root_anon_vma;
+ unsigned long anon_mapping;
+
+ rcu_read_lock();
+ anon_mapping = (unsigned long)READ_ONCE(page->mapping);
+ if ((anon_mapping & PAGE_MAPPING_FLAGS) != PAGE_MAPPING_ANON)
+ goto out;
+ if (!page_mapped(page))
+ goto out;
+
+ anon_vma = (struct anon_vma *) (anon_mapping - PAGE_MAPPING_ANON);
+ root_anon_vma = READ_ONCE(anon_vma->root);
+ if (down_read_trylock(&root_anon_vma->rwsem)) {
+ /*
+ * If the page is still mapped, then this anon_vma is still
+ * its anon_vma, and holding the mutex ensures that it will
+ * not go away, see anon_vma_free().
+ */
+ if (!page_mapped(page)) {
+ up_read(&root_anon_vma->rwsem);
+ anon_vma = NULL;
+ }
+ goto out;
+ }
+
+ /* trylock failed, we got to sleep */
+ if (!atomic_inc_not_zero(&anon_vma->refcount)) {
+ anon_vma = NULL;
+ goto out;
+ }
+
+ if (!page_mapped(page)) {
+ rcu_read_unlock();
+ put_anon_vma(anon_vma);
+ return NULL;
+ }
+
+ /* we pinned the anon_vma, its safe to sleep */
+ rcu_read_unlock();
+ anon_vma_lock_read(anon_vma);
+
+ if (atomic_dec_and_test(&anon_vma->refcount)) {
+ /*
+ * Oops, we held the last refcount, release the lock
+ * and bail -- can't simply use put_anon_vma() because
+ * we'll deadlock on the anon_vma_lock_write() recursion.
+ */
+ anon_vma_unlock_read(anon_vma);
+ __put_anon_vma(anon_vma);
+ anon_vma = NULL;
+ }
+
+ return anon_vma;
+
+out:
+ rcu_read_unlock();
+ return anon_vma;
+}
+
+void page_unlock_anon_vma_read(struct anon_vma *anon_vma)
+{
+ anon_vma_unlock_read(anon_vma);
+}
+
+/*
+ * At what user virtual address is page expected in @vma?
+ */
+static inline unsigned long
+__vma_address(struct page *page, struct vm_area_struct *vma)
+{
+ pgoff_t pgoff = page_to_pgoff(page);
+ return vma->vm_start + ((pgoff - vma->vm_pgoff) << PAGE_SHIFT);
+}
+
+inline unsigned long
+vma_address(struct page *page, struct vm_area_struct *vma)
+{
+ unsigned long address = __vma_address(page, vma);
+
+ /* page should be within @vma mapping range */
+ VM_BUG_ON_VMA(address < vma->vm_start || address >= vma->vm_end, vma);
+
+ return address;
+}
+
+/*
+ * At what user virtual address is page expected in vma?
+ * Caller should check the page is actually part of the vma.
+ */
+unsigned long page_address_in_vma(struct page *page, struct vm_area_struct *vma)
+{
+ unsigned long address;
+ if (PageAnon(page)) {
+ struct anon_vma *page__anon_vma = page_anon_vma(page);
+ /*
+ * Note: swapoff's unuse_vma() is more efficient with this
+ * check, and needs it to match anon_vma when KSM is active.
+ */
+ if (!vma->anon_vma || !page__anon_vma ||
+ vma->anon_vma->root != page__anon_vma->root)
+ return -EFAULT;
+ } else if (page->mapping) {
+ if (!vma->vm_file || vma->vm_file->f_mapping != page->mapping)
+ return -EFAULT;
+ } else
+ return -EFAULT;
+ address = __vma_address(page, vma);
+ if (unlikely(address < vma->vm_start || address >= vma->vm_end))
+ return -EFAULT;
+ return address;
+}
+
+pmd_t *mm_find_pmd(struct mm_struct *mm, unsigned long address)
+{
+ pgd_t *pgd;
+ pud_t *pud;
+ pmd_t *pmd = NULL;
+ pmd_t pmde;
+
+ pgd = pgd_offset(mm, address);
+ if (!pgd_present(*pgd))
+ goto out;
+
+ pud = pud_offset(pgd, address);
+ if (!pud_present(*pud))
+ goto out;
+
+ pmd = pmd_offset(pud, address);
+ /*
+ * Some THP functions use the sequence pmdp_clear_flush(), set_pmd_at()
+ * without holding anon_vma lock for write. So when looking for a
+ * genuine pmde (in which to find pte), test present and !THP together.
+ */
+ pmde = *pmd;
+ barrier();
+ if (!pmd_present(pmde) || pmd_trans_huge(pmde))
+ pmd = NULL;
+out:
+ return pmd;
+}
+
+/*
+ * Check that @page is mapped at @address into @mm.
+ *
+ * If @sync is false, page_check_address may perform a racy check to avoid
+ * the page table lock when the pte is not present (helpful when reclaiming
+ * highly shared pages).
+ *
+ * On success returns with pte mapped and locked.
+ */
+pte_t *__page_check_address(struct page *page, struct mm_struct *mm,
+ unsigned long address, spinlock_t **ptlp, int sync)
+{
+ pmd_t *pmd;
+ pte_t *pte;
+ spinlock_t *ptl;
+
+ if (unlikely(PageHuge(page))) {
+ /* when pud is not present, pte will be NULL */
+ pte = huge_pte_offset(mm, address);
+ if (!pte)
+ return NULL;
+
+ ptl = huge_pte_lockptr(page_hstate(page), mm, pte);
+ goto check;
+ }
+
+ pmd = mm_find_pmd(mm, address);
+ if (!pmd)
+ return NULL;
+
+ pte = pte_offset_map(pmd, address);
+ /* Make a quick check before getting the lock */
+ if (!sync && !pte_present(*pte)) {
+ pte_unmap(pte);
+ return NULL;
+ }
+
+ ptl = pte_lockptr(mm, pmd);
+check:
+ spin_lock(ptl);
+ if (pte_present(*pte) && page_to_pfn(page) == pte_pfn(*pte)) {
+ *ptlp = ptl;
+ return pte;
+ }
+ pte_unmap_unlock(pte, ptl);
+ return NULL;
+}
+
+/**
+ * page_mapped_in_vma - check whether a page is really mapped in a VMA
+ * @page: the page to test
+ * @vma: the VMA to test
+ *
+ * Returns 1 if the page is mapped into the page tables of the VMA, 0
+ * if the page is not mapped into the page tables of this VMA. Only
+ * valid for normal file or anonymous VMAs.
+ */
+int page_mapped_in_vma(struct page *page, struct vm_area_struct *vma)
+{
+ unsigned long address;
+ pte_t *pte;
+ spinlock_t *ptl;
+
+ address = __vma_address(page, vma);
+ if (unlikely(address < vma->vm_start || address >= vma->vm_end))
+ return 0;
+ pte = page_check_address(page, vma->vm_mm, address, &ptl, 1);
+ if (!pte) /* the page is not in this mm */
+ return 0;
+ pte_unmap_unlock(pte, ptl);
+
+ return 1;
+}
+
+struct page_referenced_arg {
+ int mapcount;
+ int referenced;
+ unsigned long vm_flags;
+ struct mem_cgroup *memcg;
+};
+/*
+ * arg: page_referenced_arg will be passed
+ */
+static int page_referenced_one(struct page *page, struct vm_area_struct *vma,
+ unsigned long address, void *arg)
+{
+ struct mm_struct *mm = vma->vm_mm;
+ spinlock_t *ptl;
+ int referenced = 0;
+ struct page_referenced_arg *pra = arg;
+
+ if (unlikely(PageTransHuge(page))) {
+ pmd_t *pmd;
+
+ /*
+ * rmap might return false positives; we must filter
+ * these out using page_check_address_pmd().
+ */
+ pmd = page_check_address_pmd(page, mm, address,
+ PAGE_CHECK_ADDRESS_PMD_FLAG, &ptl);
+ if (!pmd)
+ return SWAP_AGAIN;
+
+ if (vma->vm_flags & VM_LOCKED) {
+ spin_unlock(ptl);
+ pra->vm_flags |= VM_LOCKED;
+ return SWAP_FAIL; /* To break the loop */
+ }
+
+ /* go ahead even if the pmd is pmd_trans_splitting() */
+ if (pmdp_clear_flush_young_notify(vma, address, pmd))
+ referenced++;
+ spin_unlock(ptl);
+ } else {
+ pte_t *pte;
+
+ /*
+ * rmap might return false positives; we must filter
+ * these out using page_check_address().
+ */
+ pte = page_check_address(page, mm, address, &ptl, 0);
+ if (!pte)
+ return SWAP_AGAIN;
+
+ if (vma->vm_flags & VM_LOCKED) {
+ pte_unmap_unlock(pte, ptl);
+ pra->vm_flags |= VM_LOCKED;
+ return SWAP_FAIL; /* To break the loop */
+ }
+
+ if (ptep_clear_flush_young_notify(vma, address, pte)) {
+ /*
+ * Don't treat a reference through a sequentially read
+ * mapping as such. If the page has been used in
+ * another mapping, we will catch it; if this other
+ * mapping is already gone, the unmap path will have
+ * set PG_referenced or activated the page.
+ */
+ if (likely(!(vma->vm_flags & VM_SEQ_READ)))
+ referenced++;
+ }
+ pte_unmap_unlock(pte, ptl);
+ }
+
+ if (referenced) {
+ pra->referenced++;
+ pra->vm_flags |= vma->vm_flags;
+ }
+
+ pra->mapcount--;
+ if (!pra->mapcount)
+ return SWAP_SUCCESS; /* To break the loop */
+
+ return SWAP_AGAIN;
+}
+
+static bool invalid_page_referenced_vma(struct vm_area_struct *vma, void *arg)
+{
+ struct page_referenced_arg *pra = arg;
+ struct mem_cgroup *memcg = pra->memcg;
+
+ if (!mm_match_cgroup(vma->vm_mm, memcg))
+ return true;
+
+ return false;
+}
+
+/**
+ * page_referenced - test if the page was referenced
+ * @page: the page to test
+ * @is_locked: caller holds lock on the page
+ * @memcg: target memory cgroup
+ * @vm_flags: collect encountered vma->vm_flags who actually referenced the page
+ *
+ * Quick test_and_clear_referenced for all mappings to a page,
+ * returns the number of ptes which referenced the page.
+ */
+int page_referenced(struct page *page,
+ int is_locked,
+ struct mem_cgroup *memcg,
+ unsigned long *vm_flags)
+{
+ int ret;
+ int we_locked = 0;
+ struct page_referenced_arg pra = {
+ .mapcount = page_mapcount(page),
+ .memcg = memcg,
+ };
+ struct rmap_walk_control rwc = {
+ .rmap_one = page_referenced_one,
+ .arg = (void *)&pra,
+ .anon_lock = page_lock_anon_vma_read,
+ };
+
+ *vm_flags = 0;
+ if (!page_mapped(page))
+ return 0;
+
+ if (!page_rmapping(page))
+ return 0;
+
+ if (!is_locked && (!PageAnon(page) || PageKsm(page))) {
+ we_locked = trylock_page(page);
+ if (!we_locked)
+ return 1;
+ }
+
+ /*
+ * If we are reclaiming on behalf of a cgroup, skip
+ * counting on behalf of references from different
+ * cgroups
+ */
+ if (memcg) {
+ rwc.invalid_vma = invalid_page_referenced_vma;
+ }
+
+ ret = rmap_walk(page, &rwc);
+ *vm_flags = pra.vm_flags;
+
+ if (we_locked)
+ unlock_page(page);
+
+ return pra.referenced;
+}
+
+static int page_mkclean_one(struct page *page, struct vm_area_struct *vma,
+ unsigned long address, void *arg)
+{
+ struct mm_struct *mm = vma->vm_mm;
+ pte_t *pte;
+ spinlock_t *ptl;
+ int ret = 0;
+ int *cleaned = arg;
+
+ pte = page_check_address(page, mm, address, &ptl, 1);
+ if (!pte)
+ goto out;
+
+ if (pte_dirty(*pte) || pte_write(*pte)) {
+ pte_t entry;
+
+ flush_cache_page(vma, address, pte_pfn(*pte));
+ entry = ptep_clear_flush(vma, address, pte);
+ entry = pte_wrprotect(entry);
+ entry = pte_mkclean(entry);
+ set_pte_at(mm, address, pte, entry);
+ ret = 1;
+ }
+
+ pte_unmap_unlock(pte, ptl);
+
+ if (ret) {
+ mmu_notifier_invalidate_page(mm, address);
+ (*cleaned)++;
+ }
+out:
+ return SWAP_AGAIN;
+}
+
+static bool invalid_mkclean_vma(struct vm_area_struct *vma, void *arg)
+{
+ if (vma->vm_flags & VM_SHARED)
+ return false;
+
+ return true;
+}
+
+int page_mkclean(struct page *page)
+{
+ int cleaned = 0;
+ struct address_space *mapping;
+ struct rmap_walk_control rwc = {
+ .arg = (void *)&cleaned,
+ .rmap_one = page_mkclean_one,
+ .invalid_vma = invalid_mkclean_vma,
+ };
+
+ BUG_ON(!PageLocked(page));
+
+ if (!page_mapped(page))
+ return 0;
+
+ mapping = page_mapping(page);
+ if (!mapping)
+ return 0;
+
+ rmap_walk(page, &rwc);
+
+ return cleaned;
+}
+EXPORT_SYMBOL_GPL(page_mkclean);
+
+/**
+ * page_move_anon_rmap - move a page to our anon_vma
+ * @page: the page to move to our anon_vma
+ * @vma: the vma the page belongs to
+ * @address: the user virtual address mapped
+ *
+ * When a page belongs exclusively to one process after a COW event,
+ * that page can be moved into the anon_vma that belongs to just that
+ * process, so the rmap code will not search the parent or sibling
+ * processes.
+ */
+void page_move_anon_rmap(struct page *page,
+ struct vm_area_struct *vma, unsigned long address)
+{
+ struct anon_vma *anon_vma = vma->anon_vma;
+
+ VM_BUG_ON_PAGE(!PageLocked(page), page);
+ VM_BUG_ON_VMA(!anon_vma, vma);
+ VM_BUG_ON_PAGE(page->index != linear_page_index(vma, address), page);
+
+ anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON;
+ page->mapping = (struct address_space *) anon_vma;
+}
+
+/**
+ * __page_set_anon_rmap - set up new anonymous rmap
+ * @page: Page to add to rmap
+ * @vma: VM area to add page to.
+ * @address: User virtual address of the mapping
+ * @exclusive: the page is exclusively owned by the current process
+ */
+static void __page_set_anon_rmap(struct page *page,
+ struct vm_area_struct *vma, unsigned long address, int exclusive)
+{
+ struct anon_vma *anon_vma = vma->anon_vma;
+
+ BUG_ON(!anon_vma);
+
+ if (PageAnon(page))
+ return;
+
+ /*
+ * If the page isn't exclusively mapped into this vma,
+ * we must use the _oldest_ possible anon_vma for the
+ * page mapping!
+ */
+ if (!exclusive)
+ anon_vma = anon_vma->root;
+
+ anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON;
+ page->mapping = (struct address_space *) anon_vma;
+ page->index = linear_page_index(vma, address);
+}
+
+/**
+ * __page_check_anon_rmap - sanity check anonymous rmap addition
+ * @page: the page to add the mapping to
+ * @vma: the vm area in which the mapping is added
+ * @address: the user virtual address mapped
+ */
+static void __page_check_anon_rmap(struct page *page,
+ struct vm_area_struct *vma, unsigned long address)
+{
+#ifdef CONFIG_DEBUG_VM
+ /*
+ * The page's anon-rmap details (mapping and index) are guaranteed to
+ * be set up correctly at this point.
+ *
+ * We have exclusion against page_add_anon_rmap because the caller
+ * always holds the page locked, except if called from page_dup_rmap,
+ * in which case the page is already known to be setup.
+ *
+ * We have exclusion against page_add_new_anon_rmap because those pages
+ * are initially only visible via the pagetables, and the pte is locked
+ * over the call to page_add_new_anon_rmap.
+ */
+ BUG_ON(page_anon_vma(page)->root != vma->anon_vma->root);
+ BUG_ON(page->index != linear_page_index(vma, address));
+#endif
+}
+
+/**
+ * page_add_anon_rmap - add pte mapping to an anonymous page
+ * @page: the page to add the mapping to
+ * @vma: the vm area in which the mapping is added
+ * @address: the user virtual address mapped
+ *
+ * The caller needs to hold the pte lock, and the page must be locked in
+ * the anon_vma case: to serialize mapping,index checking after setting,
+ * and to ensure that PageAnon is not being upgraded racily to PageKsm
+ * (but PageKsm is never downgraded to PageAnon).
+ */
+void page_add_anon_rmap(struct page *page,
+ struct vm_area_struct *vma, unsigned long address)
+{
+ do_page_add_anon_rmap(page, vma, address, 0);
+}
+
+/*
+ * Special version of the above for do_swap_page, which often runs
+ * into pages that are exclusively owned by the current process.
+ * Everybody else should continue to use page_add_anon_rmap above.
+ */
+void do_page_add_anon_rmap(struct page *page,
+ struct vm_area_struct *vma, unsigned long address, int exclusive)
+{
+ int first = atomic_inc_and_test(&page->_mapcount);
+ if (first) {
+ /*
+ * We use the irq-unsafe __{inc|mod}_zone_page_stat because
+ * these counters are not modified in interrupt context, and
+ * pte lock(a spinlock) is held, which implies preemption
+ * disabled.
+ */
+ if (PageTransHuge(page))
+ __inc_zone_page_state(page,
+ NR_ANON_TRANSPARENT_HUGEPAGES);
+ __mod_zone_page_state(page_zone(page), NR_ANON_PAGES,
+ hpage_nr_pages(page));
+ }
+ if (unlikely(PageKsm(page)))
+ return;
+
+ VM_BUG_ON_PAGE(!PageLocked(page), page);
+ /* address might be in next vma when migration races vma_adjust */
+ if (first)
+ __page_set_anon_rmap(page, vma, address, exclusive);
+ else
+ __page_check_anon_rmap(page, vma, address);
+}
+
+/**
+ * page_add_new_anon_rmap - add pte mapping to a new anonymous page
+ * @page: the page to add the mapping to
+ * @vma: the vm area in which the mapping is added
+ * @address: the user virtual address mapped
+ *
+ * Same as page_add_anon_rmap but must only be called on *new* pages.
+ * This means the inc-and-test can be bypassed.
+ * Page does not have to be locked.
+ */
+void page_add_new_anon_rmap(struct page *page,
+ struct vm_area_struct *vma, unsigned long address)
+{
+ VM_BUG_ON_VMA(address < vma->vm_start || address >= vma->vm_end, vma);
+ SetPageSwapBacked(page);
+ atomic_set(&page->_mapcount, 0); /* increment count (starts at -1) */
+ if (PageTransHuge(page))
+ __inc_zone_page_state(page, NR_ANON_TRANSPARENT_HUGEPAGES);
+ __mod_zone_page_state(page_zone(page), NR_ANON_PAGES,
+ hpage_nr_pages(page));
+ __page_set_anon_rmap(page, vma, address, 1);
+}
+
+/**
+ * page_add_file_rmap - add pte mapping to a file page
+ * @page: the page to add the mapping to
+ *
+ * The caller needs to hold the pte lock.
+ */
+void page_add_file_rmap(struct page *page)
+{
+ struct mem_cgroup *memcg;
+
+ memcg = mem_cgroup_begin_page_stat(page);
+ if (atomic_inc_and_test(&page->_mapcount)) {
+ __inc_zone_page_state(page, NR_FILE_MAPPED);
+ mem_cgroup_inc_page_stat(memcg, MEM_CGROUP_STAT_FILE_MAPPED);
+ }
+ mem_cgroup_end_page_stat(memcg);
+}
+
+static void page_remove_file_rmap(struct page *page)
+{
+ struct mem_cgroup *memcg;
+
+ memcg = mem_cgroup_begin_page_stat(page);
+
+ /* page still mapped by someone else? */
+ if (!atomic_add_negative(-1, &page->_mapcount))
+ goto out;
+
+ /* Hugepages are not counted in NR_FILE_MAPPED for now. */
+ if (unlikely(PageHuge(page)))
+ goto out;
+
+ /*
+ * We use the irq-unsafe __{inc|mod}_zone_page_stat because
+ * these counters are not modified in interrupt context, and
+ * pte lock(a spinlock) is held, which implies preemption disabled.
+ */
+ __dec_zone_page_state(page, NR_FILE_MAPPED);
+ mem_cgroup_dec_page_stat(memcg, MEM_CGROUP_STAT_FILE_MAPPED);
+
+ if (unlikely(PageMlocked(page)))
+ clear_page_mlock(page);
+out:
+ mem_cgroup_end_page_stat(memcg);
+}
+
+/**
+ * page_remove_rmap - take down pte mapping from a page
+ * @page: page to remove mapping from
+ *
+ * The caller needs to hold the pte lock.
+ */
+void page_remove_rmap(struct page *page)
+{
+ if (!PageAnon(page)) {
+ page_remove_file_rmap(page);
+ return;
+ }
+
+ /* page still mapped by someone else? */
+ if (!atomic_add_negative(-1, &page->_mapcount))
+ return;
+
+ /* Hugepages are not counted in NR_ANON_PAGES for now. */
+ if (unlikely(PageHuge(page)))
+ return;
+
+ /*
+ * We use the irq-unsafe __{inc|mod}_zone_page_stat because
+ * these counters are not modified in interrupt context, and
+ * pte lock(a spinlock) is held, which implies preemption disabled.
+ */
+ if (PageTransHuge(page))
+ __dec_zone_page_state(page, NR_ANON_TRANSPARENT_HUGEPAGES);
+
+ __mod_zone_page_state(page_zone(page), NR_ANON_PAGES,
+ -hpage_nr_pages(page));
+
+ if (unlikely(PageMlocked(page)))
+ clear_page_mlock(page);
+
+ /*
+ * It would be tidy to reset the PageAnon mapping here,
+ * but that might overwrite a racing page_add_anon_rmap
+ * which increments mapcount after us but sets mapping
+ * before us: so leave the reset to free_hot_cold_page,
+ * and remember that it's only reliable while mapped.
+ * Leaving it set also helps swapoff to reinstate ptes
+ * faster for those pages still in swapcache.
+ */
+}
+
+/*
+ * @arg: enum ttu_flags will be passed to this argument
+ */
+static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
+ unsigned long address, void *arg)
+{
+ struct mm_struct *mm = vma->vm_mm;
+ pte_t *pte;
+ pte_t pteval;
+ spinlock_t *ptl;
+ int ret = SWAP_AGAIN;
+ enum ttu_flags flags = (enum ttu_flags)arg;
+
+ pte = page_check_address(page, mm, address, &ptl, 0);
+ if (!pte)
+ goto out;
+
+ /*
+ * If the page is mlock()d, we cannot swap it out.
+ * If it's recently referenced (perhaps page_referenced
+ * skipped over this mm) then we should reactivate it.
+ */
+ if (!(flags & TTU_IGNORE_MLOCK)) {
+ if (vma->vm_flags & VM_LOCKED)
+ goto out_mlock;
+
+ if (flags & TTU_MUNLOCK)
+ goto out_unmap;
+ }
+ if (!(flags & TTU_IGNORE_ACCESS)) {
+ if (ptep_clear_flush_young_notify(vma, address, pte)) {
+ ret = SWAP_FAIL;
+ goto out_unmap;
+ }
+ }
+
+ /* Nuke the page table entry. */
+ flush_cache_page(vma, address, page_to_pfn(page));
+ pteval = ptep_clear_flush(vma, address, pte);
+
+ /* Move the dirty bit to the physical page now the pte is gone. */
+ if (pte_dirty(pteval))
+ set_page_dirty(page);
+
+ /* Update high watermark before we lower rss */
+ update_hiwater_rss(mm);
+
+ if (PageHWPoison(page) && !(flags & TTU_IGNORE_HWPOISON)) {
+ if (!PageHuge(page)) {
+ if (PageAnon(page))
+ dec_mm_counter(mm, MM_ANONPAGES);
+ else
+ dec_mm_counter(mm, MM_FILEPAGES);
+ }
+ set_pte_at(mm, address, pte,
+ swp_entry_to_pte(make_hwpoison_entry(page)));
+ } else if (pte_unused(pteval)) {
+ /*
+ * The guest indicated that the page content is of no
+ * interest anymore. Simply discard the pte, vmscan
+ * will take care of the rest.
+ */
+ if (PageAnon(page))
+ dec_mm_counter(mm, MM_ANONPAGES);
+ else
+ dec_mm_counter(mm, MM_FILEPAGES);
+ } else if (PageAnon(page)) {
+ swp_entry_t entry = { .val = page_private(page) };
+ pte_t swp_pte;
+
+ if (PageSwapCache(page)) {
+ /*
+ * Store the swap location in the pte.
+ * See handle_pte_fault() ...
+ */
+ if (swap_duplicate(entry) < 0) {
+ set_pte_at(mm, address, pte, pteval);
+ ret = SWAP_FAIL;
+ goto out_unmap;
+ }
+ if (list_empty(&mm->mmlist)) {
+ spin_lock(&mmlist_lock);
+ if (list_empty(&mm->mmlist))
+ list_add(&mm->mmlist, &init_mm.mmlist);
+ spin_unlock(&mmlist_lock);
+ }
+ dec_mm_counter(mm, MM_ANONPAGES);
+ inc_mm_counter(mm, MM_SWAPENTS);
+ } else if (IS_ENABLED(CONFIG_MIGRATION)) {
+ /*
+ * Store the pfn of the page in a special migration
+ * pte. do_swap_page() will wait until the migration
+ * pte is removed and then restart fault handling.
+ */
+ BUG_ON(!(flags & TTU_MIGRATION));
+ entry = make_migration_entry(page, pte_write(pteval));
+ }
+ swp_pte = swp_entry_to_pte(entry);
+ if (pte_soft_dirty(pteval))
+ swp_pte = pte_swp_mksoft_dirty(swp_pte);
+ set_pte_at(mm, address, pte, swp_pte);
+ } else if (IS_ENABLED(CONFIG_MIGRATION) &&
+ (flags & TTU_MIGRATION)) {
+ /* Establish migration entry for a file page */
+ swp_entry_t entry;
+ entry = make_migration_entry(page, pte_write(pteval));
+ set_pte_at(mm, address, pte, swp_entry_to_pte(entry));
+ } else
+ dec_mm_counter(mm, MM_FILEPAGES);
+
+ page_remove_rmap(page);
+ page_cache_release(page);
+
+out_unmap:
+ pte_unmap_unlock(pte, ptl);
+ if (ret != SWAP_FAIL && !(flags & TTU_MUNLOCK))
+ mmu_notifier_invalidate_page(mm, address);
+out:
+ return ret;
+
+out_mlock:
+ pte_unmap_unlock(pte, ptl);
+
+
+ /*
+ * We need mmap_sem locking, Otherwise VM_LOCKED check makes
+ * unstable result and race. Plus, We can't wait here because
+ * we now hold anon_vma->rwsem or mapping->i_mmap_rwsem.
+ * if trylock failed, the page remain in evictable lru and later
+ * vmscan could retry to move the page to unevictable lru if the
+ * page is actually mlocked.
+ */
+ if (down_read_trylock(&vma->vm_mm->mmap_sem)) {
+ if (vma->vm_flags & VM_LOCKED) {
+ mlock_vma_page(page);
+ ret = SWAP_MLOCK;
+ }
+ up_read(&vma->vm_mm->mmap_sem);
+ }
+ return ret;
+}
+
+bool is_vma_temporary_stack(struct vm_area_struct *vma)
+{
+ int maybe_stack = vma->vm_flags & (VM_GROWSDOWN | VM_GROWSUP);
+
+ if (!maybe_stack)
+ return false;
+
+ if ((vma->vm_flags & VM_STACK_INCOMPLETE_SETUP) ==
+ VM_STACK_INCOMPLETE_SETUP)
+ return true;
+
+ return false;
+}
+
+static bool invalid_migration_vma(struct vm_area_struct *vma, void *arg)
+{
+ return is_vma_temporary_stack(vma);
+}
+
+static int page_not_mapped(struct page *page)
+{
+ return !page_mapped(page);
+};
+
+/**
+ * try_to_unmap - try to remove all page table mappings to a page
+ * @page: the page to get unmapped
+ * @flags: action and flags
+ *
+ * Tries to remove all the page table entries which are mapping this
+ * page, used in the pageout path. Caller must hold the page lock.
+ * Return values are:
+ *
+ * SWAP_SUCCESS - we succeeded in removing all mappings
+ * SWAP_AGAIN - we missed a mapping, try again later
+ * SWAP_FAIL - the page is unswappable
+ * SWAP_MLOCK - page is mlocked.
+ */
+int try_to_unmap(struct page *page, enum ttu_flags flags)
+{
+ int ret;
+ struct rmap_walk_control rwc = {
+ .rmap_one = try_to_unmap_one,
+ .arg = (void *)flags,
+ .done = page_not_mapped,
+ .anon_lock = page_lock_anon_vma_read,
+ };
+
+ VM_BUG_ON_PAGE(!PageHuge(page) && PageTransHuge(page), page);
+
+ /*
+ * During exec, a temporary VMA is setup and later moved.
+ * The VMA is moved under the anon_vma lock but not the
+ * page tables leading to a race where migration cannot
+ * find the migration ptes. Rather than increasing the
+ * locking requirements of exec(), migration skips
+ * temporary VMAs until after exec() completes.
+ */
+ if ((flags & TTU_MIGRATION) && !PageKsm(page) && PageAnon(page))
+ rwc.invalid_vma = invalid_migration_vma;
+
+ ret = rmap_walk(page, &rwc);
+
+ if (ret != SWAP_MLOCK && !page_mapped(page))
+ ret = SWAP_SUCCESS;
+ return ret;
+}
+
+/**
+ * try_to_munlock - try to munlock a page
+ * @page: the page to be munlocked
+ *
+ * Called from munlock code. Checks all of the VMAs mapping the page
+ * to make sure nobody else has this page mlocked. The page will be
+ * returned with PG_mlocked cleared if no other vmas have it mlocked.
+ *
+ * Return values are:
+ *
+ * SWAP_AGAIN - no vma is holding page mlocked, or,
+ * SWAP_AGAIN - page mapped in mlocked vma -- couldn't acquire mmap sem
+ * SWAP_FAIL - page cannot be located at present
+ * SWAP_MLOCK - page is now mlocked.
+ */
+int try_to_munlock(struct page *page)
+{
+ int ret;
+ struct rmap_walk_control rwc = {
+ .rmap_one = try_to_unmap_one,
+ .arg = (void *)TTU_MUNLOCK,
+ .done = page_not_mapped,
+ .anon_lock = page_lock_anon_vma_read,
+
+ };
+
+ VM_BUG_ON_PAGE(!PageLocked(page) || PageLRU(page), page);
+
+ ret = rmap_walk(page, &rwc);
+ return ret;
+}
+
+void __put_anon_vma(struct anon_vma *anon_vma)
+{
+ struct anon_vma *root = anon_vma->root;
+
+ anon_vma_free(anon_vma);
+ if (root != anon_vma && atomic_dec_and_test(&root->refcount))
+ anon_vma_free(root);
+}
+
+static struct anon_vma *rmap_walk_anon_lock(struct page *page,
+ struct rmap_walk_control *rwc)
+{
+ struct anon_vma *anon_vma;
+
+ if (rwc->anon_lock)
+ return rwc->anon_lock(page);
+
+ /*
+ * Note: remove_migration_ptes() cannot use page_lock_anon_vma_read()
+ * because that depends on page_mapped(); but not all its usages
+ * are holding mmap_sem. Users without mmap_sem are required to
+ * take a reference count to prevent the anon_vma disappearing
+ */
+ anon_vma = page_anon_vma(page);
+ if (!anon_vma)
+ return NULL;
+
+ anon_vma_lock_read(anon_vma);
+ return anon_vma;
+}
+
+/*
+ * rmap_walk_anon - do something to anonymous page using the object-based
+ * rmap method
+ * @page: the page to be handled
+ * @rwc: control variable according to each walk type
+ *
+ * Find all the mappings of a page using the mapping pointer and the vma chains
+ * contained in the anon_vma struct it points to.
+ *
+ * When called from try_to_munlock(), the mmap_sem of the mm containing the vma
+ * where the page was found will be held for write. So, we won't recheck
+ * vm_flags for that VMA. That should be OK, because that vma shouldn't be
+ * LOCKED.
+ */
+static int rmap_walk_anon(struct page *page, struct rmap_walk_control *rwc)
+{
+ struct anon_vma *anon_vma;
+ pgoff_t pgoff;
+ struct anon_vma_chain *avc;
+ int ret = SWAP_AGAIN;
+
+ anon_vma = rmap_walk_anon_lock(page, rwc);
+ if (!anon_vma)
+ return ret;
+
+ pgoff = page_to_pgoff(page);
+ anon_vma_interval_tree_foreach(avc, &anon_vma->rb_root, pgoff, pgoff) {
+ struct vm_area_struct *vma = avc->vma;
+ unsigned long address = vma_address(page, vma);
+
+ if (rwc->invalid_vma && rwc->invalid_vma(vma, rwc->arg))
+ continue;
+
+ ret = rwc->rmap_one(page, vma, address, rwc->arg);
+ if (ret != SWAP_AGAIN)
+ break;
+ if (rwc->done && rwc->done(page))
+ break;
+ }
+ anon_vma_unlock_read(anon_vma);
+ return ret;
+}
+
+/*
+ * rmap_walk_file - do something to file page using the object-based rmap method
+ * @page: the page to be handled
+ * @rwc: control variable according to each walk type
+ *
+ * Find all the mappings of a page using the mapping pointer and the vma chains
+ * contained in the address_space struct it points to.
+ *
+ * When called from try_to_munlock(), the mmap_sem of the mm containing the vma
+ * where the page was found will be held for write. So, we won't recheck
+ * vm_flags for that VMA. That should be OK, because that vma shouldn't be
+ * LOCKED.
+ */
+static int rmap_walk_file(struct page *page, struct rmap_walk_control *rwc)
+{
+ struct address_space *mapping = page->mapping;
+ pgoff_t pgoff;
+ struct vm_area_struct *vma;
+ int ret = SWAP_AGAIN;
+
+ /*
+ * The page lock not only makes sure that page->mapping cannot
+ * suddenly be NULLified by truncation, it makes sure that the
+ * structure at mapping cannot be freed and reused yet,
+ * so we can safely take mapping->i_mmap_rwsem.
+ */
+ VM_BUG_ON_PAGE(!PageLocked(page), page);
+
+ if (!mapping)
+ return ret;
+
+ pgoff = page_to_pgoff(page);
+ i_mmap_lock_read(mapping);
+ vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff, pgoff) {
+ unsigned long address = vma_address(page, vma);
+
+ if (rwc->invalid_vma && rwc->invalid_vma(vma, rwc->arg))
+ continue;
+
+ ret = rwc->rmap_one(page, vma, address, rwc->arg);
+ if (ret != SWAP_AGAIN)
+ goto done;
+ if (rwc->done && rwc->done(page))
+ goto done;
+ }
+
+done:
+ i_mmap_unlock_read(mapping);
+ return ret;
+}
+
+int rmap_walk(struct page *page, struct rmap_walk_control *rwc)
+{
+ if (unlikely(PageKsm(page)))
+ return rmap_walk_ksm(page, rwc);
+ else if (PageAnon(page))
+ return rmap_walk_anon(page, rwc);
+ else
+ return rmap_walk_file(page, rwc);
+}
+
+#ifdef CONFIG_HUGETLB_PAGE
+/*
+ * The following three functions are for anonymous (private mapped) hugepages.
+ * Unlike common anonymous pages, anonymous hugepages have no accounting code
+ * and no lru code, because we handle hugepages differently from common pages.
+ */
+static void __hugepage_set_anon_rmap(struct page *page,
+ struct vm_area_struct *vma, unsigned long address, int exclusive)
+{
+ struct anon_vma *anon_vma = vma->anon_vma;
+
+ BUG_ON(!anon_vma);
+
+ if (PageAnon(page))
+ return;
+ if (!exclusive)
+ anon_vma = anon_vma->root;
+
+ anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON;
+ page->mapping = (struct address_space *) anon_vma;
+ page->index = linear_page_index(vma, address);
+}
+
+void hugepage_add_anon_rmap(struct page *page,
+ struct vm_area_struct *vma, unsigned long address)
+{
+ struct anon_vma *anon_vma = vma->anon_vma;
+ int first;
+
+ BUG_ON(!PageLocked(page));
+ BUG_ON(!anon_vma);
+ /* address might be in next vma when migration races vma_adjust */
+ first = atomic_inc_and_test(&page->_mapcount);
+ if (first)
+ __hugepage_set_anon_rmap(page, vma, address, 0);
+}
+
+void hugepage_add_new_anon_rmap(struct page *page,
+ struct vm_area_struct *vma, unsigned long address)
+{
+ BUG_ON(address < vma->vm_start || address >= vma->vm_end);
+ atomic_set(&page->_mapcount, 0);
+ __hugepage_set_anon_rmap(page, vma, address, 1);
+}
+#endif /* CONFIG_HUGETLB_PAGE */
Code Review / kvmfornfv.git / blobdiff