Re: [PATCH 3/9] migrate: add hugepage migration code tomigrate_pages()
From: Naoya Horiguchi
Date: Wed Aug 14 2013 - 21:15:55 EST
On Wed, Aug 14, 2013 at 04:41:00PM -0700, Andrew Morton wrote:
> On Fri, 9 Aug 2013 01:21:36 -0400 Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx> wrote:
>
> > +static void check_hugetlb_pmd_range(struct vm_area_struct *vma, pmd_t *pmd,
> > + const nodemask_t *nodes, unsigned long flags,
> > + void *private)
> > +{
> > +#ifdef CONFIG_HUGETLB_PAGE
> > + int nid;
> > + struct page *page;
> > +
> > + spin_lock(&vma->vm_mm->page_table_lock);
> > + page = pte_page(huge_ptep_get((pte_t *)pmd));
> > + nid = page_to_nid(page);
> > + if (node_isset(nid, *nodes) == !!(flags & MPOL_MF_INVERT))
> > + goto unlock;
> > + /* With MPOL_MF_MOVE, we migrate only unshared hugepage. */
> > + if (flags & (MPOL_MF_MOVE_ALL) ||
> > + (flags & MPOL_MF_MOVE && page_mapcount(page) == 1))
> > + isolate_huge_page(page, private);
> > +unlock:
> > + spin_unlock(&vma->vm_mm->page_table_lock);
> > +#else
> > + BUG();
> > +#endif
> > +}
>
> The function is poorly named. What does it "check"? And it does more
> than checking things - at actually makes alterations!
I named like this because it became a new member of check_range() family.
So it's better to rename all of the family. An attached patch does this.
> Can we have a better name here please, and some docmentation explaining
> what it does and why it does it?
I also added some comment on check_range().
Thanks,
Naoya
---
From: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
Date: Wed, 14 Aug 2013 20:28:35 -0400
Subject: [PATCH] mempolicy: rename check_*range to queue_pages_*range
The function check_range() (and its family) is not well-named, because
it does not only checking something, but moving pages from list to list
to do page migration for them.
So queue_pages_*range is more desirable name.
Signed-off-by: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
---
mm/mempolicy.c | 41 +++++++++++++++++++++++------------------
1 file changed, 23 insertions(+), 18 deletions(-)
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 4a03c14..dca5225 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -473,8 +473,11 @@ static const struct mempolicy_operations mpol_ops[MPOL_MAX] = {
static void migrate_page_add(struct page *page, struct list_head *pagelist,
unsigned long flags);
-/* Scan through pages checking if pages follow certain conditions. */
-static int check_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
+/*
+ * Scan through pages checking if pages follow certain conditions,
+ * and move them to the pagelist if they do.
+ */
+static int queue_pages_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
unsigned long addr, unsigned long end,
const nodemask_t *nodes, unsigned long flags,
void *private)
@@ -512,8 +515,8 @@ static int check_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
return addr != end;
}
-static void check_hugetlb_pmd_range(struct vm_area_struct *vma, pmd_t *pmd,
- const nodemask_t *nodes, unsigned long flags,
+static void queue_pages_hugetlb_pmd_range(struct vm_area_struct *vma,
+ pmd_t *pmd, const nodemask_t *nodes, unsigned long flags,
void *private)
{
#ifdef CONFIG_HUGETLB_PAGE
@@ -536,7 +539,7 @@ static void check_hugetlb_pmd_range(struct vm_area_struct *vma, pmd_t *pmd,
#endif
}
-static inline int check_pmd_range(struct vm_area_struct *vma, pud_t *pud,
+static inline int queue_pages_pmd_range(struct vm_area_struct *vma, pud_t *pud,
unsigned long addr, unsigned long end,
const nodemask_t *nodes, unsigned long flags,
void *private)
@@ -548,21 +551,21 @@ static inline int check_pmd_range(struct vm_area_struct *vma, pud_t *pud,
do {
next = pmd_addr_end(addr, end);
if (pmd_huge(*pmd) && is_vm_hugetlb_page(vma)) {
- check_hugetlb_pmd_range(vma, pmd, nodes,
+ queue_pages_hugetlb_pmd_range(vma, pmd, nodes,
flags, private);
continue;
}
split_huge_page_pmd(vma, addr, pmd);
if (pmd_none_or_trans_huge_or_clear_bad(pmd))
continue;
- if (check_pte_range(vma, pmd, addr, next, nodes,
+ if (queue_pages_pte_range(vma, pmd, addr, next, nodes,
flags, private))
return -EIO;
} while (pmd++, addr = next, addr != end);
return 0;
}
-static inline int check_pud_range(struct vm_area_struct *vma, pgd_t *pgd,
+static inline int queue_pages_pud_range(struct vm_area_struct *vma, pgd_t *pgd,
unsigned long addr, unsigned long end,
const nodemask_t *nodes, unsigned long flags,
void *private)
@@ -577,14 +580,14 @@ static inline int check_pud_range(struct vm_area_struct *vma, pgd_t *pgd,
continue;
if (pud_none_or_clear_bad(pud))
continue;
- if (check_pmd_range(vma, pud, addr, next, nodes,
+ if (queue_pages_pmd_range(vma, pud, addr, next, nodes,
flags, private))
return -EIO;
} while (pud++, addr = next, addr != end);
return 0;
}
-static inline int check_pgd_range(struct vm_area_struct *vma,
+static inline int queue_pages_pgd_range(struct vm_area_struct *vma,
unsigned long addr, unsigned long end,
const nodemask_t *nodes, unsigned long flags,
void *private)
@@ -597,7 +600,7 @@ static inline int check_pgd_range(struct vm_area_struct *vma,
next = pgd_addr_end(addr, end);
if (pgd_none_or_clear_bad(pgd))
continue;
- if (check_pud_range(vma, pgd, addr, next, nodes,
+ if (queue_pages_pud_range(vma, pgd, addr, next, nodes,
flags, private))
return -EIO;
} while (pgd++, addr = next, addr != end);
@@ -635,12 +638,14 @@ static unsigned long change_prot_numa(struct vm_area_struct *vma,
#endif /* CONFIG_ARCH_USES_NUMA_PROT_NONE */
/*
- * Check if all pages in a range are on a set of nodes.
- * If pagelist != NULL then isolate pages from the LRU and
- * put them on the pagelist.
+ * Walk through page tables and collect pages to be migrated.
+ *
+ * If pages found in a given range are on a set of nodes (determined by
+ * @nodes and @flags,) it's isolated and queued to the pagelist which is
+ * passed via @private.)
*/
static struct vm_area_struct *
-check_range(struct mm_struct *mm, unsigned long start, unsigned long end,
+queue_pages_range(struct mm_struct *mm, unsigned long start, unsigned long end,
const nodemask_t *nodes, unsigned long flags, void *private)
{
int err;
@@ -675,7 +680,7 @@ check_range(struct mm_struct *mm, unsigned long start, unsigned long end,
((flags & (MPOL_MF_MOVE | MPOL_MF_MOVE_ALL)) &&
vma_migratable(vma))) {
- err = check_pgd_range(vma, start, endvma, nodes,
+ err = queue_pages_pgd_range(vma, start, endvma, nodes,
flags, private);
if (err) {
first = ERR_PTR(err);
@@ -1041,7 +1046,7 @@ static int migrate_to_node(struct mm_struct *mm, int source, int dest,
* space range and MPOL_MF_DISCONTIG_OK, this call can not fail.
*/
VM_BUG_ON(!(flags & (MPOL_MF_MOVE | MPOL_MF_MOVE_ALL)));
- check_range(mm, mm->mmap->vm_start, mm->task_size, &nmask,
+ queue_pages_range(mm, mm->mmap->vm_start, mm->task_size, &nmask,
flags | MPOL_MF_DISCONTIG_OK, &pagelist);
if (!list_empty(&pagelist)) {
@@ -1279,7 +1284,7 @@ static long do_mbind(unsigned long start, unsigned long len,
if (err)
goto mpol_out;
- vma = check_range(mm, start, end, nmask,
+ vma = queue_pages_range(mm, start, end, nmask,
flags | MPOL_MF_INVERT, &pagelist);
err = PTR_ERR(vma); /* maybe ... */
--
1.8.3.1
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