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mm/mpol: Use special PROT_NONE to migrate pages

tip:sched/numa In review tip-bot for Peter Zijlstra 2 participants 3 messages Sep 27, 2012 – Oct 4, 2012

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#0 lore raw
Commit-ID:  39d6cb39a81744473e13c693a9f988a9e342018b
Gitweb:     http://git.kernel.org/tip/39d6cb39a81744473e13c693a9f988a9e342018b
Author:     Peter Zijlstra <[email protected]>
AuthorDate: Tue, 17 Jul 2012 22:54:51 +0200
Committer:  Ingo Molnar <[email protected]>
CommitDate: Wed, 26 Sep 2012 11:48:35 +0200

mm/mpol: Use special PROT_NONE to migrate pages

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

Suggested-by Rik van Riel <[email protected]>
Signed-off-by Peter Zijlstra <[email protected]>
Reviewed-by Rik van Riel <[email protected]>
Cc Paul Turner <[email protected]>
Cc Linus Torvalds <[email protected]>
Cc Andrew Morton <[email protected]>
Link http://lkml.kernel.org/n/[email protected] open here
Signed-off-by Ingo Molnar <[email protected]>
---
 mm/huge_memory.c |   41 ++++++++++++++++++++++++++++++++++++++++-
 mm/memory.c      |   42 ++++++++++++++++++++++++++++++++++++------
 2 files changed, 76 insertions(+), 7 deletions(-)
mm/huge_memory.c +40 -1
index 5d7b114..a147d29 100644
@@ -17,6 +17,7 @@
 #include <linux/khugepaged.h>
 #include <linux/freezer.h>
 #include <linux/mman.h>
+#include <linux/migrate.h>
 #include <asm/tlb.h>
 #include <asm/pgalloc.h>
 #include "internal.h"

@@ -766,12 +767,48 @@ void do_huge_pmd_prot_none(struct mm_struct *mm, struct vm_area_struct *vma,
 			   unsigned int flags, pmd_t entry)
 {
 	unsigned long haddr = address & HPAGE_PMD_MASK;
+	struct page *page = NULL;
+	int node;
 
 	spin_lock(&mm->page_table_lock);
 	if (unlikely(!pmd_same(*pmd, entry)))
 		goto out_unlock;
 
-	/* do fancy stuff */
+	if (unlikely(pmd_trans_splitting(entry))) {
+		spin_unlock(&mm->page_table_lock);
+		wait_split_huge_page(vma->anon_vma, pmd);
+		return;
+	}
+
+#ifdef CONFIG_NUMA
+	page = pmd_page(entry);
+	VM_BUG_ON(!PageCompound(page) || !PageHead(page));
+
+	get_page(page);
+	spin_unlock(&mm->page_table_lock);
+
+	/*
+	 * XXX should we serialize against split_huge_page ?
+	 */
+
+	node = mpol_misplaced(page, vma, haddr);
+	if (node == -1)
+		goto do_fixup;
+
+	/*
+	 * 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;
+
+do_fixup:
+	spin_lock(&mm->page_table_lock);
+	if (unlikely(!pmd_same(*pmd, entry)))
+		goto out_unlock;
+#endif
 
 	/* change back to regular protection */
 	entry = pmd_modify(entry, vma->vm_page_prot);

@@ -780,6 +817,8 @@ void do_huge_pmd_prot_none(struct mm_struct *mm, struct vm_area_struct *vma,
 
 out_unlock:
 	spin_unlock(&mm->page_table_lock);
+	if (page)
+		put_page(page);
 }
 
 int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm,
mm/memory.c +36 -6

73 lines not on this page · raw message

#1 lore raw

PATCH 1/1 mm/mpol: Fix build warning for UMA kernels

"mm, mpol: Use special PROT_NONE to migrate pages" causes a build warning when CONFIG_NUMA is not enabled:

mm/huge_memory.c: In function 'do_huge_pmd_prot_none':
mm/huge_memory.c:745: warning: unused variable 'node'

"node" is only used once, so avoid using it altogether.

Signed-off-by David Rientjes <[email protected]>
---
 mm/huge_memory.c |    4 +---
 1 files changed, 1 insertions(+), 3 deletions(-)
mm/huge_memory.c +1 -3
@@ -742,7 +742,6 @@ void do_huge_pmd_prot_none(struct mm_struct *mm, struct vm_area_struct *vma,
 {
 	unsigned long haddr = address & HPAGE_PMD_MASK;
 	struct page *page = NULL;
-	int node;
 
 	spin_lock(&mm->page_table_lock);
 	if (unlikely(!pmd_same(*pmd, entry)))

@@ -765,8 +764,7 @@ void do_huge_pmd_prot_none(struct mm_struct *mm, struct vm_area_struct *vma,
 	 * XXX should we serialize against split_huge_page ?
 	 */
 
-	node = mpol_misplaced(page, vma, haddr, mm->numa_big);
-	if (node == -1)
+	if (mpol_misplaced(page, vma, haddr, mm->numa_big) == -1)
 		goto do_fixup;
 
 	/*
#2 lore raw

[tip:sched/numa] mm/mpol: Fix build warning for UMA kernels

Commit-ID:  d886931968a1c7e7bc7d4891cbd12cecf3111bd0
Gitweb:     http://git.kernel.org/tip/d886931968a1c7e7bc7d4891cbd12cecf3111bd0
Author:     David Rientjes <[email protected]>
AuthorDate: Tue, 2 Oct 2012 13:14:10 -0700
Committer:  Ingo Molnar <[email protected]>
CommitDate: Thu, 4 Oct 2012 10:15:16 +0200

mm/mpol: Fix build warning for UMA kernels

Commit "mm, mpol: Use special PROT_NONE to migrate pages" causes a build warning when CONFIG_NUMA is not enabled:

mm/huge_memory.c: In function 'do_huge_pmd_prot_none':
mm/huge_memory.c:745: warning: unused variable 'node'

"node" is only used once, so avoid using it altogether.

Signed-off-by David Rientjes <[email protected]>
Cc [email protected]
Cc Linus Torvalds <[email protected]>
Cc Rik van Riel <[email protected]>
Cc Peter Zijlstra <[email protected]>
Link http://lkml.kernel.org/r/[email protected] open here
Signed-off-by Ingo Molnar <[email protected]>
---
 mm/huge_memory.c |    4 +---
 1 files changed, 1 insertions(+), 3 deletions(-)
mm/huge_memory.c +1 -3
index 4a9ea86..2e2a814 100644
@@ -768,7 +768,6 @@ void do_huge_pmd_prot_none(struct mm_struct *mm, struct vm_area_struct *vma,
 {
 	unsigned long haddr = address & HPAGE_PMD_MASK;
 	struct page *page = NULL;
-	int node;
 
 	spin_lock(&mm->page_table_lock);
 	if (unlikely(!pmd_same(*pmd, entry)))

@@ -791,8 +790,7 @@ void do_huge_pmd_prot_none(struct mm_struct *mm, struct vm_area_struct *vma,
 	 * XXX should we serialize against split_huge_page ?
 	 */
 
-	node = mpol_misplaced(page, vma, haddr, mm->numa_big);
-	if (node == -1)
+	if (mpol_misplaced(page, vma, haddr, mm->numa_big) == -1)
 		goto do_fixup;
 
 	/*