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Subject[PATCH -mm v2 05/11] pagewalk: remove mm_walk->skip
Date
Due to the relocation of pmd locking, mm_walk->skip becomes less important
because only walk_page_test() and walk->test_walk() use it. None of these
functions uses a positive value as a return value, so we can define it to
determine whether we skip the current vma or not.
Thus this patch removes mm_walk->skip.

Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
---
fs/proc/task_mmu.c | 4 ++--
include/linux/mm.h | 3 ---
mm/mempolicy.c | 9 ++++-----
mm/pagewalk.c | 36 ++++++++----------------------------
4 files changed, 14 insertions(+), 38 deletions(-)

diff --git mmotm-2014-05-21-16-57.orig/fs/proc/task_mmu.c mmotm-2014-05-21-16-57/fs/proc/task_mmu.c
index 059206ea3c6b..8211f6c8236d 100644
--- mmotm-2014-05-21-16-57.orig/fs/proc/task_mmu.c
+++ mmotm-2014-05-21-16-57/fs/proc/task_mmu.c
@@ -755,9 +755,9 @@ static int clear_refs_test_walk(unsigned long start, unsigned long end,
* Writing 4 to /proc/pid/clear_refs affects all pages.
*/
if (cp->type == CLEAR_REFS_ANON && vma->vm_file)
- walk->skip = 1;
+ return 1;
if (cp->type == CLEAR_REFS_MAPPED && !vma->vm_file)
- walk->skip = 1;
+ return 1;
if (cp->type == CLEAR_REFS_SOFT_DIRTY) {
if (vma->vm_flags & VM_SOFTDIRTY)
vma->vm_flags &= ~VM_SOFTDIRTY;
diff --git mmotm-2014-05-21-16-57.orig/include/linux/mm.h mmotm-2014-05-21-16-57/include/linux/mm.h
index aa832161a1ff..0a20674c84e2 100644
--- mmotm-2014-05-21-16-57.orig/include/linux/mm.h
+++ mmotm-2014-05-21-16-57/include/linux/mm.h
@@ -1106,8 +1106,6 @@ void unmap_vmas(struct mmu_gather *tlb, struct vm_area_struct *start_vma,
* right now." 0 means "skip the current vma."
* @mm: mm_struct representing the target process of page table walk
* @vma: vma currently walked
- * @skip: internal control flag which is set when we skip the lower
- * level entries.
* @pmd: current pmd entry
* @ptl: page table lock associated with current entry
* @private: private data for callbacks' use
@@ -1127,7 +1125,6 @@ struct mm_walk {
struct mm_walk *walk);
struct mm_struct *mm;
struct vm_area_struct *vma;
- int skip;
pmd_t *pmd;
spinlock_t *ptl;
void *private;
diff --git mmotm-2014-05-21-16-57.orig/mm/mempolicy.c mmotm-2014-05-21-16-57/mm/mempolicy.c
index cf3b995b21d0..b8267f753748 100644
--- mmotm-2014-05-21-16-57.orig/mm/mempolicy.c
+++ mmotm-2014-05-21-16-57/mm/mempolicy.c
@@ -596,22 +596,21 @@ static int queue_pages_test_walk(unsigned long start, unsigned long end,
}

qp->prev = vma;
- walk->skip = 1;

if (vma->vm_flags & VM_PFNMAP)
- return 0;
+ return 1;

if (flags & MPOL_MF_LAZY) {
change_prot_numa(vma, start, endvma);
- return 0;
+ return 1;
}

if ((flags & MPOL_MF_STRICT) ||
((flags & (MPOL_MF_MOVE | MPOL_MF_MOVE_ALL)) &&
vma_migratable(vma)))
/* queue pages from current vma */
- walk->skip = 0;
- return 0;
+ return 0;
+ return 1;
}

/*
diff --git mmotm-2014-05-21-16-57.orig/mm/pagewalk.c mmotm-2014-05-21-16-57/mm/pagewalk.c
index f1a3417d0b51..61d6bd9545d6 100644
--- mmotm-2014-05-21-16-57.orig/mm/pagewalk.c
+++ mmotm-2014-05-21-16-57/mm/pagewalk.c
@@ -3,24 +3,6 @@
#include <linux/sched.h>
#include <linux/hugetlb.h>

-/*
- * Check the current skip status of page table walker.
- *
- * Here what I mean by skip is to skip lower level walking, and that was
- * determined for each entry independently. For example, when walk_pmd_range
- * handles a pmd_trans_huge we don't have to walk over ptes under that pmd,
- * and the skipping does not affect the walking over ptes under other pmds.
- * That's why we reset @walk->skip after tested.
- */
-static bool skip_lower_level_walking(struct mm_walk *walk)
-{
- if (walk->skip) {
- walk->skip = 0;
- return true;
- }
- return false;
-}
-
static int walk_pte_range(pmd_t *pmd, unsigned long addr,
unsigned long end, struct mm_walk *walk)
{
@@ -89,8 +71,6 @@ static int walk_pmd_range(pud_t *pud, unsigned long addr,
err = walk->pmd_entry(pmd, addr, next, walk);
spin_unlock(walk->ptl);
}
- if (skip_lower_level_walking(walk))
- continue;
if (err)
break;
}
@@ -225,9 +205,9 @@ static inline int walk_hugetlb_range(unsigned long addr, unsigned long end,

/*
* Decide whether we really walk over the current vma on [@start, @end)
- * or skip it. When we skip it, we set @walk->skip to 1.
- * The return value is used to control the page table walking to
- * continue (for zero) or not (for non-zero).
+ * or skip it via the returned value. Return 0 if we do walk over the
+ * current vma, and return 1 if we skip the vma. Negative values means
+ * error, where we abort the current walk.
*
* Default check (only VM_PFNMAP check for now) is used when the caller
* doesn't define test_walk() callback.
@@ -245,7 +225,7 @@ static int walk_page_test(unsigned long start, unsigned long end,
* page backing a VM_PFNMAP range. See also commit a9ff785e4437.
*/
if (vma->vm_flags & VM_PFNMAP)
- walk->skip = 1;
+ return 1;
return 0;
}

@@ -330,9 +310,9 @@ int walk_page_range(unsigned long start, unsigned long end,
next = min(end, vma->vm_end);

err = walk_page_test(start, next, walk);
- if (skip_lower_level_walking(walk))
+ if (err == 1)
continue;
- if (err)
+ if (err < 0)
break;
}
err = __walk_page_range(start, next, walk);
@@ -353,9 +333,9 @@ int walk_page_vma(struct vm_area_struct *vma, struct mm_walk *walk)
VM_BUG_ON(!vma);
walk->vma = vma;
err = walk_page_test(vma->vm_start, vma->vm_end, walk);
- if (skip_lower_level_walking(walk))
+ if (err == 1)
return 0;
- if (err)
+ if (err < 0)
return err;
return __walk_page_range(vma->vm_start, vma->vm_end, walk);
}
--
1.9.3


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