[3.8.y.z extended stable] Patch "mm: numa: call MMU notifiers on THP migration" has been added to staging queue

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

    mm: numa: call MMU notifiers on THP migration

to the linux-3.8.y-queue branch of the 3.8.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.8.y-queue

This patch is scheduled to be released in version 3.8.13.16.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.8.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

>From 6abccabc00fb6d9251c0a3a1bdf9bcd8afd257d9 Mon Sep 17 00:00:00 2001
From: Mel Gorman <mgorman at suse.de>
Date: Wed, 18 Dec 2013 17:08:33 -0800
Subject: mm: numa: call MMU notifiers on THP migration

commit f714f4f20e59ea6eea264a86b9a51fd51b88fc54 upstream.

MMU notifiers must be called on THP page migration or secondary MMUs
will get very confused.

Signed-off-by: Mel Gorman <mgorman at suse.de>
Reviewed-by: Rik van Riel <riel at redhat.com>
Cc: Alex Thorlton <athorlton at sgi.com>
Signed-off-by: Andrew Morton <akpm at linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds at linux-foundation.org>
[ kamal: backport to 3.8 (context) ]
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 mm/migrate.c | 22 ++++++++++++++--------
 1 file changed, 14 insertions(+), 8 deletions(-)

diff --git a/mm/migrate.c b/mm/migrate.c
index 09c881c..6344541 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -36,6 +36,7 @@
 #include <linux/hugetlb_cgroup.h>
 #include <linux/gfp.h>
 #include <linux/balloon_compaction.h>
+#include <linux/mmu_notifier.h>

 #include <asm/tlbflush.h>

@@ -1665,12 +1666,13 @@ int migrate_misplaced_transhuge_page(struct mm_struct *mm,
 				unsigned long address,
 				struct page *page, int node)
 {
-	unsigned long haddr = address & HPAGE_PMD_MASK;
 	pg_data_t *pgdat = NODE_DATA(node);
 	int isolated = 0;
 	struct page *new_page = NULL;
 	struct mem_cgroup *memcg = NULL;
 	int page_lru = page_is_file_cache(page);
+	unsigned long mmun_start = address & HPAGE_PMD_MASK;
+	unsigned long mmun_end = mmun_start + HPAGE_PMD_SIZE;
 	pmd_t orig_entry;

 	/*
@@ -1712,10 +1714,12 @@ int migrate_misplaced_transhuge_page(struct mm_struct *mm,
 	WARN_ON(PageLRU(new_page));

 	/* Recheck the target PMD */
+	mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
 	spin_lock(&mm->page_table_lock);
 	if (unlikely(!pmd_same(*pmd, entry) || page_count(page) != 2)) {
 fail_putback:
 		spin_unlock(&mm->page_table_lock);
+		mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);

 		/* Reverse changes made by migrate_page_copy() */
 		if (TestClearPageActive(new_page))
@@ -1756,15 +1760,16 @@ fail_putback:
 	 * The SetPageUptodate on the new page and page_add_new_anon_rmap
 	 * guarantee the copy is visible before the pagetable update.
 	 */
-	flush_cache_range(vma, haddr, haddr + HPAGE_PMD_SIZE);
-	page_add_new_anon_rmap(new_page, vma, haddr);
-	pmdp_clear_flush(vma, haddr, pmd);
-	set_pmd_at(mm, haddr, pmd, entry);
+	flush_cache_range(vma, mmun_start, mmun_end);
+	page_add_new_anon_rmap(new_page, vma, mmun_start);
+	pmdp_clear_flush(vma, mmun_start, pmd);
+	set_pmd_at(mm, mmun_start, pmd, entry);
+	flush_tlb_range(vma, mmun_start, mmun_end);
 	update_mmu_cache_pmd(vma, address, &entry);

 	if (page_count(page) != 2) {
-		set_pmd_at(mm, haddr, pmd, orig_entry);
-		flush_tlb_range(vma, haddr, haddr + HPAGE_PMD_SIZE);
+		set_pmd_at(mm, mmun_start, pmd, orig_entry);
+		flush_tlb_range(vma, mmun_start, mmun_end);
 		update_mmu_cache_pmd(vma, address, &entry);
 		page_remove_rmap(new_page);
 		goto fail_putback;
@@ -1779,6 +1784,7 @@ fail_putback:
 	 */
 	mem_cgroup_end_migration(memcg, page, new_page, true);
 	spin_unlock(&mm->page_table_lock);
+	mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);

 	unlock_page(new_page);
 	unlock_page(page);
@@ -1799,7 +1805,7 @@ out_dropref:
 	spin_lock(&mm->page_table_lock);
 	if (pmd_same(*pmd, entry)) {
 		entry = pmd_mknonnuma(entry);
-		set_pmd_at(mm, haddr, pmd, entry);
+		set_pmd_at(mm, mmun_start, pmd, entry);
 		update_mmu_cache_pmd(vma, address, &entry);
 	}
 	spin_unlock(&mm->page_table_lock);
--
1.8.3.2