[PATCH 13/52] mm/mempolicy: Use _PAGE_NUMA to migrate pages

From: Ingo Molnar
Date: Sun Dec 02 2012 - 13:44:18 EST

From: Mel Gorman <mgorman@xxxxxxx>

Note: Based on "mm/mpol: Use special PROT_NONE to migrate pages"
but sufficiently different that the signed-off-bys were dropped

Combine our previous _PAGE_NUMA, mpol_misplaced and
migrate_misplaced_page() pieces into an effective migrate on
fault scheme.

Note that (on x86) we rely on PROT_NONE pages being !present and
avoid the TLB flush from try_to_unmap(TTU_MIGRATION). This
greatly improves the page-migration performance.

Based-on-work-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Signed-off-by: Mel Gorman <mgorman@xxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Paul Turner <pjt@xxxxxxxxxx>
Cc: Lee Schermerhorn <Lee.Schermerhorn@xxxxxx>
Cc: Alex Shi <lkml.alex@xxxxxxxxx>
Cc: Srikar Dronamraju <srikar@xxxxxxxxxxxxxxxxxx>
Cc: Aneesh Kumar <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
include/linux/huge_mm.h | 8 ++++----
mm/huge_memory.c | 31 ++++++++++++++++++++++++++++---
mm/memory.c | 32 +++++++++++++++++++++++++++-----
3 files changed, 59 insertions(+), 12 deletions(-)

diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
index 6cd7dcb..dabb510 100644
--- a/include/linux/huge_mm.h
+++ b/include/linux/huge_mm.h
@@ -160,8 +160,8 @@ static inline struct page *compound_trans_head(struct page *page)
return page;
}

-extern int do_huge_pmd_numa_page(struct mm_struct *mm, unsigned long addr,
- pmd_t pmd, pmd_t *pmdp);
+extern int do_huge_pmd_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,
+ unsigned long addr, pmd_t pmd, pmd_t *pmdp);

#else /* CONFIG_TRANSPARENT_HUGEPAGE */
#define HPAGE_PMD_SHIFT ({ BUILD_BUG(); 0; })
@@ -200,8 +200,8 @@ static inline int pmd_trans_huge_lock(pmd_t *pmd,
return 0;
}

-static inline int do_huge_pmd_numa_page(struct mm_struct *mm, unsigned long addr,
- pmd_t pmd, pmd_t *pmdp)
+static inline int do_huge_pmd_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,
+ unsigned long addr, pmd_t pmd, pmd_t *pmdp)
{
return 0;
}
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 900eb1b..5723b55 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -18,6 +18,7 @@
#include <linux/freezer.h>
#include <linux/mman.h>
#include <linux/pagemap.h>
+#include <linux/migrate.h>
#include <asm/tlb.h>
#include <asm/pgalloc.h>
#include "internal.h"
@@ -1019,17 +1020,39 @@ out:
}

/* NUMA hinting page fault entry point for trans huge pmds */
-int do_huge_pmd_numa_page(struct mm_struct *mm, unsigned long addr,
- pmd_t pmd, pmd_t *pmdp)
+int do_huge_pmd_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,
+ unsigned long addr, pmd_t pmd, pmd_t *pmdp)
{
+ struct page *page = NULL;
unsigned long haddr = addr & HPAGE_PMD_MASK;
- struct page *page;
+ int target_nid;

spin_lock(&mm->page_table_lock);
if (unlikely(!pmd_same(pmd, *pmdp)))
goto out_unlock;

page = pmd_page(pmd);
+ get_page(page);
+ spin_unlock(&mm->page_table_lock);
+
+ target_nid = mpol_misplaced(page, vma, haddr);
+ if (target_nid == -1)
+ goto clear_pmdnuma;
+
+ /*
+ * Due to lacking code to migrate thp pages, we'll split
+ * (which preserves the special PROT_NONE) and re-take the
+ * fault on the normal pages.
+ */
+ split_huge_page(page);
+ put_page(page);
+ return 0;
+
+clear_pmdnuma:
+ spin_lock(&mm->page_table_lock);
+ if (unlikely(!pmd_same(pmd, *pmdp)))
+ goto out_unlock;
+
pmd = pmd_mknonnuma(pmd);
set_pmd_at(mm, haddr, pmdp, pmd);
VM_BUG_ON(pmd_numa(*pmdp));
@@ -1037,6 +1060,8 @@ int do_huge_pmd_numa_page(struct mm_struct *mm, unsigned long addr,

out_unlock:
spin_unlock(&mm->page_table_lock);
+ if (page)
+ put_page(page);
return 0;
}

diff --git a/mm/memory.c b/mm/memory.c
index 290b80a..174f006 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -57,6 +57,7 @@
#include <linux/swapops.h>
#include <linux/elf.h>
#include <linux/gfp.h>
+#include <linux/migrate.h>

#include <asm/io.h>
#include <asm/pgalloc.h>
@@ -3451,8 +3452,9 @@ static int do_nonlinear_fault(struct mm_struct *mm, struct vm_area_struct *vma,
int do_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,
unsigned long addr, pte_t pte, pte_t *ptep, pmd_t *pmd)
{
- struct page *page;
+ struct page *page = NULL;
spinlock_t *ptl;
+ int current_nid, target_nid;

/*
* The "pte" at this point cannot be used safely without
@@ -3465,8 +3467,11 @@ int do_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,
*/
ptl = pte_lockptr(mm, pmd);
spin_lock(ptl);
- if (unlikely(!pte_same(*ptep, pte)))
- goto out_unlock;
+ if (unlikely(!pte_same(*ptep, pte))) {
+ pte_unmap_unlock(ptep, ptl);
+ goto out;
+ }
+
pte = pte_mknonnuma(pte);
set_pte_at(mm, addr, ptep, pte);
update_mmu_cache(vma, addr, ptep);
@@ -3477,8 +3482,25 @@ int do_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,
return 0;
}

-out_unlock:
+ get_page(page);
+ current_nid = page_to_nid(page);
+ target_nid = mpol_misplaced(page, vma, addr);
pte_unmap_unlock(ptep, ptl);
+ if (target_nid == -1) {
+ /*
+ * Account for the fault against the current node if it not
+ * being replaced regardless of where the page is located.
+ */
+ current_nid = numa_node_id();
+ put_page(page);
+ goto out;
+ }
+
+ /* Migrate to the requested node */
+ if (migrate_misplaced_page(page, target_nid))
+ current_nid = target_nid;
+
+out:
return 0;
}

@@ -3647,7 +3669,7 @@ retry:
barrier();
if (pmd_trans_huge(orig_pmd)) {
if (pmd_numa(*pmd))
- return do_huge_pmd_numa_page(mm, address,
+ return do_huge_pmd_numa_page(mm, vma, address,
orig_pmd, pmd);

if ((flags & FAULT_FLAG_WRITE) && !pmd_write(orig_pmd)) {
--
1.7.11.7

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