lkml.org 
[lkml]   [2013]   [Oct]   [30]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 04/11] clear_refs: redefine callback functions for page table walker
Date
Currently clear_refs_pte_range() is connected to pmd_entry() to split thps
if found. But now this work can be done in core page table walker code.
So we have no reason to keep this callback on pmd_entry(). This patch moves
pte handling code on pte_entry() callback.

clear_refs_write() has some prechecks about if we really walk over a given
vma. It's fine to let them done by test_walk() callback, so let's define it.

Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
---
fs/proc/task_mmu.c | 82 ++++++++++++++++++++++--------------------------------
1 file changed, 33 insertions(+), 49 deletions(-)

diff --git v3.12-rc7-mmots-2013-10-29-16-24.orig/fs/proc/task_mmu.c v3.12-rc7-mmots-2013-10-29-16-24/fs/proc/task_mmu.c
index ed79a9c..3e1b739 100644
--- v3.12-rc7-mmots-2013-10-29-16-24.orig/fs/proc/task_mmu.c
+++ v3.12-rc7-mmots-2013-10-29-16-24/fs/proc/task_mmu.c
@@ -719,7 +719,6 @@ enum clear_refs_types {
};

struct clear_refs_private {
- struct vm_area_struct *vma;
enum clear_refs_types type;
};

@@ -751,41 +750,43 @@ static inline void clear_soft_dirty(struct vm_area_struct *vma,
#endif
}

-static int clear_refs_pte_range(pmd_t *pmd, unsigned long addr,
+static int clear_refs_pte(pte_t *pte, unsigned long addr,
unsigned long end, struct mm_walk *walk)
{
struct clear_refs_private *cp = walk->private;
- struct vm_area_struct *vma = cp->vma;
- pte_t *pte, ptent;
- spinlock_t *ptl;
+ struct vm_area_struct *vma = walk->vma;
struct page *page;

- split_huge_page_pmd(vma, addr, pmd);
- if (pmd_trans_unstable(pmd))
+ if (cp->type == CLEAR_REFS_SOFT_DIRTY) {
+ clear_soft_dirty(vma, addr, pte);
return 0;
+ }
+ if (!pte_present(*pte))
+ return 0;
+ page = vm_normal_page(vma, addr, *pte);
+ if (!page)
+ return 0;
+ /* Clear accessed and referenced bits. */
+ ptep_test_and_clear_young(vma, addr, pte);
+ ClearPageReferenced(page);
+ return 0;
+}

- pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
- for (; addr != end; pte++, addr += PAGE_SIZE) {
- ptent = *pte;
-
- if (cp->type == CLEAR_REFS_SOFT_DIRTY) {
- clear_soft_dirty(vma, addr, pte);
- continue;
- }
-
- if (!pte_present(ptent))
- continue;
-
- page = vm_normal_page(vma, addr, ptent);
- if (!page)
- continue;
+static int clear_refs_test_walk(unsigned long start, unsigned long end,
+ struct mm_walk *walk)
+{
+ struct clear_refs_private *cp = walk->private;
+ struct vm_area_struct *vma = walk->vma;

- /* Clear accessed and referenced bits. */
- ptep_test_and_clear_young(vma, addr, pte);
- ClearPageReferenced(page);
- }
- pte_unmap_unlock(pte - 1, ptl);
- cond_resched();
+ /*
+ * Writing 1 to /proc/pid/clear_refs affects all pages.
+ * Writing 2 to /proc/pid/clear_refs only affects anonymous pages.
+ * Writing 3 to /proc/pid/clear_refs only affects file mapped pages.
+ */
+ if (cp->type == CLEAR_REFS_ANON && vma->vm_file)
+ walk->skip = 1;
+ if (cp->type == CLEAR_REFS_MAPPED && !vma->vm_file)
+ walk->skip = 1;
return 0;
}

@@ -827,33 +828,16 @@ static ssize_t clear_refs_write(struct file *file, const char __user *buf,
.type = type,
};
struct mm_walk clear_refs_walk = {
- .pmd_entry = clear_refs_pte_range,
+ .pte_entry = clear_refs_pte,
+ .test_walk = clear_refs_test_walk,
.mm = mm,
.private = &cp,
};
down_read(&mm->mmap_sem);
if (type == CLEAR_REFS_SOFT_DIRTY)
mmu_notifier_invalidate_range_start(mm, 0, -1);
- for (vma = mm->mmap; vma; vma = vma->vm_next) {
- cp.vma = vma;
- if (is_vm_hugetlb_page(vma))
- continue;
- /*
- * Writing 1 to /proc/pid/clear_refs affects all pages.
- *
- * Writing 2 to /proc/pid/clear_refs only affects
- * Anonymous pages.
- *
- * Writing 3 to /proc/pid/clear_refs only affects file
- * mapped pages.
- */
- if (type == CLEAR_REFS_ANON && vma->vm_file)
- continue;
- if (type == CLEAR_REFS_MAPPED && !vma->vm_file)
- continue;
- walk_page_range(vma->vm_start, vma->vm_end,
- &clear_refs_walk);
- }
+ for (vma = mm->mmap; vma; vma = vma->vm_next)
+ walk_page_vma(vma, &clear_refs_walk);
if (type == CLEAR_REFS_SOFT_DIRTY)
mmu_notifier_invalidate_range_end(mm, 0, -1);
flush_tlb_mm(mm);
--
1.8.3.1


\
 
 \ /
  Last update: 2013-10-30 23:21    [W:0.078 / U:11.200 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site