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-rw-r--r--mm/mremap.c18
1 files changed, 16 insertions, 2 deletions
diff --git a/mm/mremap.c b/mm/mremap.c
index a39b7b91be46..97bff2547719 100644
--- a/mm/mremap.c
+++ b/mm/mremap.c
@@ -11,6 +11,7 @@
#include <linux/hugetlb.h>
#include <linux/slab.h>
#include <linux/shm.h>
+#include <linux/ksm.h>
#include <linux/mman.h>
#include <linux/swap.h>
#include <linux/capability.h>
@@ -85,8 +86,8 @@ static void move_ptes(struct vm_area_struct *vma, pmd_t *old_pmd,
if (vma->vm_file) {
/*
* Subtle point from Rajesh Venkatasubramanian: before
- * moving file-based ptes, we must lock vmtruncate out,
- * since it might clean the dst vma before the src vma,
+ * moving file-based ptes, we must lock truncate_pagecache
+ * out, since it might clean the dst vma before the src vma,
* and we propagate stale pages into the dst afterward.
*/
mapping = vma->vm_file->f_mapping;
@@ -174,6 +175,7 @@ static unsigned long move_vma(struct vm_area_struct *vma,
unsigned long excess = 0;
unsigned long hiwater_vm;
int split = 0;
+ int err;
/*
* We'd prefer to avoid failure later on in do_munmap:
@@ -182,6 +184,18 @@ static unsigned long move_vma(struct vm_area_struct *vma,
if (mm->map_count >= sysctl_max_map_count - 3)
return -ENOMEM;
+ /*
+ * Advise KSM to break any KSM pages in the area to be moved:
+ * it would be confusing if they were to turn up at the new
+ * location, where they happen to coincide with different KSM
+ * pages recently unmapped. But leave vma->vm_flags as it was,
+ * so KSM can come around to merge on vma and new_vma afterwards.
+ */
+ err = ksm_madvise(vma, old_addr, old_addr + old_len,
+ MADV_UNMERGEABLE, &vm_flags);
+ if (err)
+ return err;
+
new_pgoff = vma->vm_pgoff + ((old_addr - vma->vm_start) >> PAGE_SHIFT);
new_vma = copy_vma(&vma, new_addr, new_len, new_pgoff);
if (!new_vma)