On Sun, Feb 22, 2015 at 02:47:18PM +0200, Shachar Raindel wrote:
> @@ -1983,6 +1983,66 @@ static int do_page_mkwrite(struct vm_area_struct *vma, struct page *page,
> }
>
> /*
> + * Handle write page faults for pages that can be reused in the current vma
> + *
> + * This can happen either due to the mapping being with the VM_SHARED flag,
> + * or due to us being the last reference standing to the page. In either
> + * case, all we need to do here is to mark the page as writable and update
> + * any related book-keeping.
> + */
> +static int wp_page_reuse(struct mm_struct *mm, struct vm_area_struct *vma,
> + unsigned long address, pte_t *page_table,
> + spinlock_t *ptl, pte_t orig_pte,
> + struct page *page, int dirty_page,
> + int page_mkwrite, int dirty_shared)
The dirty_page parameter is not used in the function below. Is it
maybe a vestige of a previous patch version?
> + __releases(ptl)
> +{
> + pte_t entry;
> + /*
> + * Clear the pages cpupid information as the existing
> + * information potentially belongs to a now completely
> + * unrelated process.
> + */
> + if (page)
> + page_cpupid_xchg_last(page, (1 << LAST_CPUPID_SHIFT) - 1);
> +
> + flush_cache_page(vma, address, pte_pfn(orig_pte));
> + entry = pte_mkyoung(orig_pte);
> + entry = maybe_mkwrite(pte_mkdirty(entry), vma);
> + if (ptep_set_access_flags(vma, address, page_table, entry, 1))
> + update_mmu_cache(vma, address, page_table);
> + pte_unmap_unlock(page_table, ptl);
> +
> +
Spurious newline.
> + if (dirty_shared) {
> + struct address_space *mapping;
> + int dirtied;
> +
> + if (!page_mkwrite)
> + lock_page(page);
> +
> + dirtied = set_page_dirty(page);
> + VM_BUG_ON_PAGE(PageAnon(page), page);
> + mapping = page->mapping;
> + unlock_page(page);
> + page_cache_release(page);
> +
> + if ((dirtied || page_mkwrite) && mapping) {
> + /*
> + * Some device drivers do not set page.mapping
> + * but still dirty their pages
> + */
> + balance_dirty_pages_ratelimited(mapping);
> + }
> +
> + if (!page_mkwrite)
> + file_update_time(vma->vm_file);
> + }
> +
> + return VM_FAULT_WRITE;
> +}
> +
> +/*
> * This routine handles present pages, when users try to write
> * to a shared page. It is done by copying the page to a new address
> * and decrementing the shared-page counter for the old page.
> @@ -2055,12 +2114,15 @@ static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
> */
> page_move_anon_rmap(old_page, vma, address);
> unlock_page(old_page);
> - goto reuse;
> + return wp_page_reuse(mm, vma, address, page_table, ptl,
> + orig_pte, old_page, 0, 0, 0);
> }
> unlock_page(old_page);
> } else if (unlikely((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
> (VM_WRITE|VM_SHARED))) {
> + int page_mkwrite = 0;
> page_cache_get(old_page);
> +
Can you please insert a newline between variable decl and code?
Otherwise, the patch looks good to me.
Acked-by: Johannes Weiner <hannes@xxxxxxxxxxx>
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