From 28766805275c12c2298883cece3f98505ac764b4 Mon Sep 17 00:00:00 2001 From: Shachar Raindel Date: Tue, 14 Apr 2015 15:46:29 -0700 Subject: [PATCH] mm: refactor do_wp_page - rewrite the unlock flow When do_wp_page is ending, in several cases it needs to unlock the pages and ptls it was accessing. Currently, this logic was "called" by using a goto jump. This makes following the control flow of the function harder. Readability was further hampered by the unlock case containing large amount of logic needed only in one of the 3 cases. Using goto for cleanup is generally allowed. However, moving the trivial unlocking flows to the relevant call sites allow deeper refactoring in the next patch. Signed-off-by: Shachar Raindel Acked-by: Linus Torvalds Acked-by: Kirill A. Shutemov Acked-by: Rik van Riel Acked-by: Andi Kleen Acked-by: Haggai Eran Acked-by: Johannes Weiner Cc: Mel Gorman Cc: Matthew Wilcox Cc: Dave Hansen Cc: Naoya Horiguchi Cc: Andrea Arcangeli Cc: Peter Feiner Cc: Michel Lespinasse Reviewed-by: Michal Hocko Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/memory.c | 21 ++++++++++++--------- 1 file changed, 12 insertions(+), 9 deletions(-) diff --git a/mm/memory.c b/mm/memory.c index e70685f3e836..0e28fddafdaf 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -2066,7 +2066,7 @@ static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma, { struct page *old_page, *new_page = NULL; pte_t entry; - int ret = 0; + int page_copied = 0; unsigned long mmun_start = 0; /* For mmu_notifiers */ unsigned long mmun_end = 0; /* For mmu_notifiers */ struct mem_cgroup *memcg; @@ -2101,7 +2101,9 @@ static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma, &ptl); if (!pte_same(*page_table, orig_pte)) { unlock_page(old_page); - goto unlock; + pte_unmap_unlock(page_table, ptl); + page_cache_release(old_page); + return 0; } page_cache_release(old_page); } @@ -2148,7 +2150,9 @@ static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma, &ptl); if (!pte_same(*page_table, orig_pte)) { unlock_page(old_page); - goto unlock; + pte_unmap_unlock(page_table, ptl); + page_cache_release(old_page); + return 0; } page_mkwrite = 1; } @@ -2246,29 +2250,28 @@ gotten: /* Free the old page.. */ new_page = old_page; - ret |= VM_FAULT_WRITE; + page_copied = 1; } else mem_cgroup_cancel_charge(new_page, memcg); if (new_page) page_cache_release(new_page); -unlock: + pte_unmap_unlock(page_table, ptl); - if (mmun_end > mmun_start) - mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); + mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); if (old_page) { /* * Don't let another task, with possibly unlocked vma, * keep the mlocked page. */ - if ((ret & VM_FAULT_WRITE) && (vma->vm_flags & VM_LOCKED)) { + if (page_copied && (vma->vm_flags & VM_LOCKED)) { lock_page(old_page); /* LRU manipulation */ munlock_vma_page(old_page); unlock_page(old_page); } page_cache_release(old_page); } - return ret; + return page_copied ? VM_FAULT_WRITE : 0; oom_free_new: page_cache_release(new_page); oom: -- 2.20.1