The patch titled
Subject: mm: refactor do_wp_page - rewrite the unlock flow
has been added to the -mm tree. Its filename is
mm-refactor-do_wp_page-rewrite-the-unlock-flow.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-refactor-do_wp_page-rewrite-the-unlock-flow.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-refactor-do_wp_page-rewrite-the-unlock-flow.patch
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From: Shachar Raindel <raindel@xxxxxxxxxxxx>
Subject: 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 <raindel@xxxxxxxxxxxx>
Acked-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Acked-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Acked-by: Rik van Riel <riel@xxxxxxxxxx>
Acked-by: Andi Kleen <ak@xxxxxxxxxxxxxxx>
Acked-by: Haggai Eran <haggaie@xxxxxxxxxxxx>
Acked-by: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxx>
Cc: Matthew Wilcox <matthew.r.wilcox@xxxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxx>
Cc: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Cc: Peter Feiner <pfeiner@xxxxxxxxxx>
Cc: Michel Lespinasse <walken@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/memory.c | 21 ++++++++++++---------
1 file changed, 12 insertions(+), 9 deletions(-)
diff -puN mm/memory.c~mm-refactor-do_wp_page-rewrite-the-unlock-flow mm/memory.c
--- a/mm/memory.c~mm-refactor-do_wp_page-rewrite-the-unlock-flow
+++ a/mm/memory.c
@@ -2066,7 +2066,7 @@ static int do_wp_page(struct mm_struct *
{
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 *
&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 *
&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:
_
Patches currently in -mm which might be from raindel@xxxxxxxxxxxx are
mm-refactor-do_wp_page-extract-the-reuse-case.patch
mm-refactor-do_wp_page-rewrite-the-unlock-flow.patch
mm-refactor-do_wp_page-extract-the-page-copy-flow.patch
mm-refactor-do_wp_page-handling-of-shared-vma-into-a-function.patch
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