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mm: refactor do_wp_page - rewrite the unlock flow

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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@mellanox.com>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Rik van Riel <riel@redhat.com>
Acked-by: Andi Kleen <ak@linux.intel.com>
Acked-by: Haggai Eran <haggaie@mellanox.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Matthew Wilcox <matthew.r.wilcox@intel.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Peter Feiner <pfeiner@google.com>
Cc: Michel Lespinasse <walken@google.com>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Shachar Raindel 2015-04-14 15:46:29 -07:00 committed by Linus Torvalds
parent 4e047f8977
commit 2876680527
1 changed files with 12 additions and 9 deletions
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19
mm/memory.c
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@ -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 @@ static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
/* 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);
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: