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-rw-r--r--mm/memory.c133
1 files changed, 97 insertions, 36 deletions
diff --git a/mm/memory.c b/mm/memory.c
index 0ec7bc644271..7e2a4b1580e3 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -126,7 +126,7 @@ static void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd)
pmd_clear(pmd);
pte_lock_deinit(page);
pte_free_tlb(tlb, page);
- dec_page_state(nr_page_table_pages);
+ dec_zone_page_state(page, NR_PAGETABLE);
tlb->mm->nr_ptes--;
}
@@ -311,7 +311,7 @@ int __pte_alloc(struct mm_struct *mm, pmd_t *pmd, unsigned long address)
pte_free(new);
} else {
mm->nr_ptes++;
- inc_page_state(nr_page_table_pages);
+ inc_zone_page_state(new, NR_PAGETABLE);
pmd_populate(mm, pmd, new);
}
spin_unlock(&mm->page_table_lock);
@@ -434,7 +434,9 @@ copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
/* pte contains position in swap or file, so copy. */
if (unlikely(!pte_present(pte))) {
if (!pte_file(pte)) {
- swap_duplicate(pte_to_swp_entry(pte));
+ swp_entry_t entry = pte_to_swp_entry(pte);
+
+ swap_duplicate(entry);
/* make sure dst_mm is on swapoff's mmlist. */
if (unlikely(list_empty(&dst_mm->mmlist))) {
spin_lock(&mmlist_lock);
@@ -443,6 +445,16 @@ copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
&src_mm->mmlist);
spin_unlock(&mmlist_lock);
}
+ if (is_write_migration_entry(entry) &&
+ is_cow_mapping(vm_flags)) {
+ /*
+ * COW mappings require pages in both parent
+ * and child to be set to read.
+ */
+ make_migration_entry_read(&entry);
+ pte = swp_entry_to_pte(entry);
+ set_pte_at(src_mm, addr, src_pte, pte);
+ }
}
goto out_set_pte;
}
@@ -1445,25 +1457,60 @@ static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
{
struct page *old_page, *new_page;
pte_t entry;
- int ret = VM_FAULT_MINOR;
+ int reuse, ret = VM_FAULT_MINOR;
old_page = vm_normal_page(vma, address, orig_pte);
if (!old_page)
goto gotten;
- if (PageAnon(old_page) && !TestSetPageLocked(old_page)) {
- int reuse = can_share_swap_page(old_page);
- unlock_page(old_page);
- if (reuse) {
- flush_cache_page(vma, address, pte_pfn(orig_pte));
- entry = pte_mkyoung(orig_pte);
- entry = maybe_mkwrite(pte_mkdirty(entry), vma);
- ptep_set_access_flags(vma, address, page_table, entry, 1);
- update_mmu_cache(vma, address, entry);
- lazy_mmu_prot_update(entry);
- ret |= VM_FAULT_WRITE;
- goto unlock;
+ if (unlikely((vma->vm_flags & (VM_SHARED|VM_WRITE)) ==
+ (VM_SHARED|VM_WRITE))) {
+ if (vma->vm_ops && vma->vm_ops->page_mkwrite) {
+ /*
+ * Notify the address space that the page is about to
+ * become writable so that it can prohibit this or wait
+ * for the page to get into an appropriate state.
+ *
+ * We do this without the lock held, so that it can
+ * sleep if it needs to.
+ */
+ page_cache_get(old_page);
+ pte_unmap_unlock(page_table, ptl);
+
+ if (vma->vm_ops->page_mkwrite(vma, old_page) < 0)
+ goto unwritable_page;
+
+ page_cache_release(old_page);
+
+ /*
+ * Since we dropped the lock we need to revalidate
+ * the PTE as someone else may have changed it. If
+ * they did, we just return, as we can count on the
+ * MMU to tell us if they didn't also make it writable.
+ */
+ page_table = pte_offset_map_lock(mm, pmd, address,
+ &ptl);
+ if (!pte_same(*page_table, orig_pte))
+ goto unlock;
}
+
+ reuse = 1;
+ } else if (PageAnon(old_page) && !TestSetPageLocked(old_page)) {
+ reuse = can_share_swap_page(old_page);
+ unlock_page(old_page);
+ } else {
+ reuse = 0;
+ }
+
+ if (reuse) {
+ flush_cache_page(vma, address, pte_pfn(orig_pte));
+ entry = pte_mkyoung(orig_pte);
+ entry = maybe_mkwrite(pte_mkdirty(entry), vma);
+ ptep_set_access_flags(vma, address, page_table, entry, 1);
+ update_mmu_cache(vma, address, entry);
+ lazy_mmu_prot_update(entry);
+ ret |= VM_FAULT_WRITE;
+ goto unlock;
}
/*
@@ -1523,6 +1570,10 @@ oom:
if (old_page)
page_cache_release(old_page);
return VM_FAULT_OOM;
+
+unwritable_page:
+ page_cache_release(old_page);
+ return VM_FAULT_SIGBUS;
}
/*
@@ -1879,7 +1930,10 @@ static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma,
goto out;
entry = pte_to_swp_entry(orig_pte);
-again:
+ if (is_migration_entry(entry)) {
+ migration_entry_wait(mm, pmd, address);
+ goto out;
+ }
page = lookup_swap_cache(entry);
if (!page) {
swapin_readahead(entry, address, vma);
@@ -1897,18 +1951,12 @@ again:
/* Had to read the page from swap area: Major fault */
ret = VM_FAULT_MAJOR;
- inc_page_state(pgmajfault);
+ count_vm_event(PGMAJFAULT);
grab_swap_token();
}
mark_page_accessed(page);
lock_page(page);
- if (!PageSwapCache(page)) {
- /* Page migration has occured */
- unlock_page(page);
- page_cache_release(page);
- goto again;
- }
/*
* Back out if somebody else already faulted in this pte.
@@ -2074,18 +2122,31 @@ retry:
/*
* Should we do an early C-O-W break?
*/
- if (write_access && !(vma->vm_flags & VM_SHARED)) {
- struct page *page;
+ if (write_access) {
+ if (!(vma->vm_flags & VM_SHARED)) {
+ struct page *page;
- if (unlikely(anon_vma_prepare(vma)))
- goto oom;
- page = alloc_page_vma(GFP_HIGHUSER, vma, address);
- if (!page)
- goto oom;
- copy_user_highpage(page, new_page, address);
- page_cache_release(new_page);
- new_page = page;
- anon = 1;
+ if (unlikely(anon_vma_prepare(vma)))
+ goto oom;
+ page = alloc_page_vma(GFP_HIGHUSER, vma, address);
+ if (!page)
+ goto oom;
+ copy_user_highpage(page, new_page, address);
+ page_cache_release(new_page);
+ new_page = page;
+ anon = 1;
+
+ } else {
+ /* if the page will be shareable, see if the backing
+ * address space wants to know that the page is about
+ * to become writable */
+ if (vma->vm_ops->page_mkwrite &&
+ vma->vm_ops->page_mkwrite(vma, new_page) < 0
+ ) {
+ page_cache_release(new_page);
+ return VM_FAULT_SIGBUS;
+ }
+ }
}
page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
@@ -2263,7 +2324,7 @@ int __handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma,
__set_current_state(TASK_RUNNING);
- inc_page_state(pgfault);
+ count_vm_event(PGFAULT);
if (unlikely(is_vm_hugetlb_page(vma)))
return hugetlb_fault(mm, vma, address, write_access);
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-20 08:08:00 +0100