diff options
| -rw-r--r-- | fs/buffer.c | 2 | ||||
| -rw-r--r-- | include/linux/mm.h | 34 | ||||
| -rw-r--r-- | include/linux/rmap.h | 14 | ||||
| -rw-r--r-- | mm/memory.c | 29 | ||||
| -rw-r--r-- | mm/mmap.c | 10 | ||||
| -rw-r--r-- | mm/mprotect.c | 21 | ||||
| -rw-r--r-- | mm/page-writeback.c | 17 | ||||
| -rw-r--r-- | mm/rmap.c | 65 |
8 files changed, 162 insertions, 30 deletions
diff --git a/fs/buffer.c b/fs/buffer.c index 71649ef..3b6d701 100644 --- a/fs/buffer.c +++ b/fs/buffer.c @@ -2987,6 +2987,7 @@ int try_to_free_buffers(struct page *page) spin_lock(&mapping->private_lock); ret = drop_buffers(page, &buffers_to_free); + spin_unlock(&mapping->private_lock); if (ret) { /* * If the filesystem writes its buffers by hand (eg ext3) @@ -2998,7 +2999,6 @@ int try_to_free_buffers(struct page *page) */ clear_page_dirty(page); } - spin_unlock(&mapping->private_lock); out: if (buffers_to_free) { struct buffer_head *bh = buffers_to_free; diff --git a/include/linux/mm.h b/include/linux/mm.h index 7d20b25..4498414 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -15,6 +15,7 @@ #include <linux/fs.h> #include <linux/mutex.h> #include <linux/debug_locks.h> +#include <linux/backing-dev.h> struct mempolicy; struct anon_vma; @@ -810,6 +811,39 @@ struct shrinker; extern struct shrinker *set_shrinker(int, shrinker_t); extern void remove_shrinker(struct shrinker *shrinker); +/* + * Some shared mappigns will want the pages marked read-only + * to track write events. If so, we'll downgrade vm_page_prot + * to the private version (using protection_map[] without the + * VM_SHARED bit). + */ +static inline int vma_wants_writenotify(struct vm_area_struct *vma) +{ + unsigned int vm_flags = vma->vm_flags; + + /* If it was private or non-writable, the write bit is already clear */ + if ((vm_flags & (VM_WRITE|VM_SHARED)) != ((VM_WRITE|VM_SHARED))) + return 0; + + /* The backer wishes to know when pages are first written to? */ + if (vma->vm_ops && vma->vm_ops->page_mkwrite) + return 1; + + /* The open routine did something to the protections already? */ + if (pgprot_val(vma->vm_page_prot) != + pgprot_val(protection_map[vm_flags & + (VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)])) + return 0; + + /* Specialty mapping? */ + if (vm_flags & (VM_PFNMAP|VM_INSERTPAGE)) + return 0; + + /* Can the mapping track the dirty pages? */ + return vma->vm_file && vma->vm_file->f_mapping && + mapping_cap_account_dirty(vma->vm_file->f_mapping); +} + extern pte_t *FASTCALL(get_locked_pte(struct mm_struct *mm, unsigned long addr, spinlock_t **ptl)); int __pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address); diff --git a/include/linux/rmap.h b/include/linux/rmap.h index bf97b09..db2c1df 100644 --- a/include/linux/rmap.h +++ b/include/linux/rmap.h @@ -103,6 +103,14 @@ pte_t *page_check_address(struct page *, struct mm_struct *, */ unsigned long page_address_in_vma(struct page *, struct vm_area_struct *); +/* + * Cleans the PTEs of shared mappings. + * (and since clean PTEs should also be readonly, write protects them too) + * + * returns the number of cleaned PTEs. + */ +int page_mkclean(struct page *); + #else /* !CONFIG_MMU */ #define anon_vma_init() do {} while (0) @@ -112,6 +120,12 @@ unsigned long page_address_in_vma(struct page *, struct vm_area_struct *); #define page_referenced(page,l) TestClearPageReferenced(page) #define try_to_unmap(page, refs) SWAP_FAIL +static inline int page_mkclean(struct page *page) +{ + return 0; +} + + #endif /* CONFIG_MMU */ /* diff --git a/mm/memory.c b/mm/memory.c index 109e986..fa941b1 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -1458,14 +1458,19 @@ static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma, { struct page *old_page, *new_page; pte_t entry; - int reuse, ret = VM_FAULT_MINOR; + int reuse = 0, ret = VM_FAULT_MINOR; + struct page *dirty_page = NULL; old_page = vm_normal_page(vma, address, orig_pte); if (!old_page) goto gotten; - if (unlikely((vma->vm_flags & (VM_SHARED|VM_WRITE)) == - (VM_SHARED|VM_WRITE))) { + /* + * Only catch write-faults on shared writable pages, read-only + * shared pages can get COWed by get_user_pages(.write=1, .force=1). + */ + if (unlikely((vma->vm_flags & (VM_WRITE|VM_SHARED)) == + (VM_WRITE|VM_SHARED))) { if (vma->vm_ops && vma->vm_ops->page_mkwrite) { /* * Notify the address space that the page is about to @@ -1494,13 +1499,12 @@ static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma, if (!pte_same(*page_table, orig_pte)) goto unlock; } - + dirty_page = old_page; + get_page(dirty_page); 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) { @@ -1566,6 +1570,10 @@ gotten: page_cache_release(old_page); unlock: pte_unmap_unlock(page_table, ptl); + if (dirty_page) { + set_page_dirty(dirty_page); + put_page(dirty_page); + } return ret; oom: if (old_page) @@ -2098,6 +2106,7 @@ static int do_no_page(struct mm_struct *mm, struct vm_area_struct *vma, unsigned int sequence = 0; int ret = VM_FAULT_MINOR; int anon = 0; + struct page *dirty_page = NULL; pte_unmap(page_table); BUG_ON(vma->vm_flags & VM_PFNMAP); @@ -2192,6 +2201,10 @@ retry: } else { inc_mm_counter(mm, file_rss); page_add_file_rmap(new_page); + if (write_access) { + dirty_page = new_page; + get_page(dirty_page); + } } } else { /* One of our sibling threads was faster, back out. */ @@ -2204,6 +2217,10 @@ retry: lazy_mmu_prot_update(entry); unlock: pte_unmap_unlock(page_table, ptl); + if (dirty_page) { + set_page_dirty(dirty_page); + put_page(dirty_page); + } return ret; oom: page_cache_release(new_page); @@ -1105,12 +1105,6 @@ munmap_back: goto free_vma; } - /* Don't make the VMA automatically writable if it's shared, but the - * backer wishes to know when pages are first written to */ - if (vma->vm_ops && vma->vm_ops->page_mkwrite) - vma->vm_page_prot = - protection_map[vm_flags & (VM_READ|VM_WRITE|VM_EXEC)]; - /* We set VM_ACCOUNT in a shared mapping's vm_flags, to inform * shmem_zero_setup (perhaps called through /dev/zero's ->mmap) * that memory reservation must be checked; but that reservation @@ -1128,6 +1122,10 @@ munmap_back: pgoff = vma->vm_pgoff; vm_flags = vma->vm_flags; + if (vma_wants_writenotify(vma)) + vma->vm_page_prot = + protection_map[vm_flags & (VM_READ|VM_WRITE|VM_EXEC)]; + if (!file || !vma_merge(mm, prev, addr, vma->vm_end, vma->vm_flags, NULL, file, pgoff, vma_policy(vma))) { file = vma->vm_file; diff --git a/mm/mprotect.c b/mm/mprotect.c index 638edab..367b7f6 100644 --- a/mm/mprotect.c +++ b/mm/mprotect.c @@ -123,8 +123,6 @@ mprotect_fixup(struct vm_area_struct *vma, struct vm_area_struct **pprev, unsigned long oldflags = vma->vm_flags; long nrpages = (end - start) >> PAGE_SHIFT; unsigned long charged = 0; - unsigned int mask; - pgprot_t newprot; pgoff_t pgoff; int error; @@ -176,24 +174,21 @@ mprotect_fixup(struct vm_area_struct *vma, struct vm_area_struct **pprev, } success: - /* Don't make the VMA automatically writable if it's shared, but the - * backer wishes to know when pages are first written to */ - mask = VM_READ|VM_WRITE|VM_EXEC|VM_SHARED; - if (vma->vm_ops && vma->vm_ops->page_mkwrite) - mask &= ~VM_SHARED; - - newprot = protection_map[newflags & mask]; - /* * vm_flags and vm_page_prot are protected by the mmap_sem * held in write mode. */ vma->vm_flags = newflags; - vma->vm_page_prot = newprot; + vma->vm_page_prot = protection_map[newflags & + (VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)]; + if (vma_wants_writenotify(vma)) + vma->vm_page_prot = protection_map[newflags & + (VM_READ|VM_WRITE|VM_EXEC)]; + if (is_vm_hugetlb_page(vma)) - hugetlb_change_protection(vma, start, end, newprot); + hugetlb_change_protection(vma, start, end, vma->vm_page_prot); else - change_protection(vma, start, end, newprot); + change_protection(vma, start, end, vma->vm_page_prot); vm_stat_account(mm, oldflags, vma->vm_file, -nrpages); vm_stat_account(mm, newflags, vma->vm_file, nrpages); return 0; diff --git a/mm/page-writeback.c b/mm/page-writeback.c index 77a0bc4..1c87430 100644 --- a/mm/page-writeback.c +++ b/mm/page-writeback.c @@ -23,6 +23,7 @@ #include <linux/backing-dev.h> #include <linux/blkdev.h> #include <linux/mpage.h> +#include <linux/rmap.h> #include <linux/percpu.h> #include <linux/notifier.h> #include <linux/smp.h> @@ -550,7 +551,7 @@ int do_writepages(struct address_space *mapping, struct writeback_control *wbc) return 0; wbc->for_writepages = 1; if (mapping->a_ops->writepages) - ret = mapping->a_ops->writepages(mapping, wbc); + ret = mapping->a_ops->writepages(mapping, wbc); else ret = generic_writepages(mapping, wbc); wbc->for_writepages = 0; @@ -712,9 +713,15 @@ int test_clear_page_dirty(struct page *page) radix_tree_tag_clear(&mapping->page_tree, page_index(page), PAGECACHE_TAG_DIRTY); - if (mapping_cap_account_dirty(mapping)) - __dec_zone_page_state(page, NR_FILE_DIRTY); write_unlock_irqrestore(&mapping->tree_lock, flags); + /* + * We can continue to use `mapping' here because the + * page is locked, which pins the address_space + */ + if (mapping_cap_account_dirty(mapping)) { + page_mkclean(page); + dec_zone_page_state(page, NR_FILE_DIRTY); + } return 1; } write_unlock_irqrestore(&mapping->tree_lock, flags); @@ -744,8 +751,10 @@ int clear_page_dirty_for_io(struct page *page) if (mapping) { if (TestClearPageDirty(page)) { - if (mapping_cap_account_dirty(mapping)) + if (mapping_cap_account_dirty(mapping)) { + page_mkclean(page); dec_zone_page_state(page, NR_FILE_DIRTY); + } return 1; } return 0; @@ -434,6 +434,71 @@ int page_referenced(struct page *page, int is_locked) return referenced; } +static int page_mkclean_one(struct page *page, struct vm_area_struct *vma) +{ + struct mm_struct *mm = vma->vm_mm; + unsigned long address; + pte_t *pte, entry; + spinlock_t *ptl; + int ret = 0; + + address = vma_address(page, vma); + if (address == -EFAULT) + goto out; + + pte = page_check_address(page, mm, address, &ptl); + if (!pte) + goto out; + + if (!pte_dirty(*pte) && !pte_write(*pte)) + goto unlock; + + entry = ptep_get_and_clear(mm, address, pte); + entry = pte_mkclean(entry); + entry = pte_wrprotect(entry); + ptep_establish(vma, address, pte, entry); + lazy_mmu_prot_update(entry); + ret = 1; + +unlock: + pte_unmap_unlock(pte, ptl); +out: + return ret; +} + +static int page_mkclean_file(struct address_space *mapping, struct page *page) +{ + pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT); + struct vm_area_struct *vma; + struct prio_tree_iter iter; + int ret = 0; + + BUG_ON(PageAnon(page)); + + spin_lock(&mapping->i_mmap_lock); + vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) { + if (vma->vm_flags & VM_SHARED) + ret += page_mkclean_one(page, vma); + } + spin_unlock(&mapping->i_mmap_lock); + return ret; +} + +int page_mkclean(struct page *page) +{ + int ret = 0; + + BUG_ON(!PageLocked(page)); + + if (page_mapped(page)) { + struct address_space *mapping = page_mapping(page); + if (mapping) + ret = page_mkclean_file(mapping, page); + } + + return ret; +} + /** * page_set_anon_rmap - setup new anonymous rmap * @page: the page to add the mapping to |