[PATCH] get_user_pages: kill get_page_map
Since its birth, get_user_pages has been calling a misguided get_page_map function. follow_page has already returned NULL if the pfn is invalid, we cannot reach an invalid pfn from a validated struct page. Remove get_page_map, and the messy rewind in get_user_pages to cope with its failure. Oh, and could we please call that "struct page *page" like everywhere else, instead of "struct page *map"? Signed-off-by: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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parent
7c2f3fda56
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08ef472937
41
mm/memory.c
41
mm/memory.c
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@ -840,23 +840,8 @@ check_user_page_readable(struct mm_struct *mm, unsigned long address)
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{
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{
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return __follow_page(mm, address, /*read*/1, /*write*/0) != NULL;
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return __follow_page(mm, address, /*read*/1, /*write*/0) != NULL;
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}
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}
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EXPORT_SYMBOL(check_user_page_readable);
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EXPORT_SYMBOL(check_user_page_readable);
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/*
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* Given a physical address, is there a useful struct page pointing to
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* it? This may become more complex in the future if we start dealing
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* with IO-aperture pages for direct-IO.
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*/
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static inline struct page *get_page_map(struct page *page)
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{
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if (!pfn_valid(page_to_pfn(page)))
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return NULL;
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return page;
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}
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static inline int
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static inline int
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untouched_anonymous_page(struct mm_struct* mm, struct vm_area_struct *vma,
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untouched_anonymous_page(struct mm_struct* mm, struct vm_area_struct *vma,
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unsigned long address)
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unsigned long address)
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@ -887,7 +872,6 @@ untouched_anonymous_page(struct mm_struct* mm, struct vm_area_struct *vma,
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return 0;
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return 0;
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}
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}
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int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
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int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
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unsigned long start, int len, int write, int force,
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unsigned long start, int len, int write, int force,
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struct page **pages, struct vm_area_struct **vmas)
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struct page **pages, struct vm_area_struct **vmas)
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@ -951,21 +935,21 @@ int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
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}
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}
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spin_lock(&mm->page_table_lock);
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spin_lock(&mm->page_table_lock);
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do {
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do {
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struct page *map;
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struct page *page;
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int lookup_write = write;
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int lookup_write = write;
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cond_resched_lock(&mm->page_table_lock);
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cond_resched_lock(&mm->page_table_lock);
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while (!(map = follow_page(mm, start, lookup_write))) {
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while (!(page = follow_page(mm, start, lookup_write))) {
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/*
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/*
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* Shortcut for anonymous pages. We don't want
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* Shortcut for anonymous pages. We don't want
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* to force the creation of pages tables for
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* to force the creation of pages tables for
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* insanly big anonymously mapped areas that
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* insanely big anonymously mapped areas that
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* nobody touched so far. This is important
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* nobody touched so far. This is important
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* for doing a core dump for these mappings.
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* for doing a core dump for these mappings.
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*/
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*/
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if (!lookup_write &&
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if (!lookup_write &&
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untouched_anonymous_page(mm,vma,start)) {
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untouched_anonymous_page(mm,vma,start)) {
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map = ZERO_PAGE(start);
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page = ZERO_PAGE(start);
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break;
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break;
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}
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}
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spin_unlock(&mm->page_table_lock);
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spin_unlock(&mm->page_table_lock);
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@ -994,17 +978,10 @@ int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
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spin_lock(&mm->page_table_lock);
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spin_lock(&mm->page_table_lock);
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}
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}
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if (pages) {
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if (pages) {
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pages[i] = get_page_map(map);
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pages[i] = page;
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if (!pages[i]) {
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flush_dcache_page(page);
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spin_unlock(&mm->page_table_lock);
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if (!PageReserved(page))
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while (i--)
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page_cache_get(page);
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page_cache_release(pages[i]);
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i = -EFAULT;
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goto out;
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}
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flush_dcache_page(pages[i]);
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if (!PageReserved(pages[i]))
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page_cache_get(pages[i]);
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}
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}
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if (vmas)
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if (vmas)
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vmas[i] = vma;
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vmas[i] = vma;
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@ -1014,10 +991,8 @@ int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
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} while (len && start < vma->vm_end);
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} while (len && start < vma->vm_end);
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spin_unlock(&mm->page_table_lock);
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spin_unlock(&mm->page_table_lock);
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} while (len);
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} while (len);
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out:
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return i;
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return i;
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}
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}
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EXPORT_SYMBOL(get_user_pages);
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EXPORT_SYMBOL(get_user_pages);
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static int zeromap_pte_range(struct mm_struct *mm, pmd_t *pmd,
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static int zeromap_pte_range(struct mm_struct *mm, pmd_t *pmd,
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