Subject: + mm-call-mmu-notifiers-when-copying-a-hugetlb-page-range.patch added to -mm tree
To: andreas@xxxxxxxxxxxxxx,aarcange@xxxxxxxxxx,hughd@xxxxxxxxxx,marc.zyngier@xxxxxxx,mgorman@xxxxxxx,riel@xxxxxxxxxx,steve.capper@xxxxxxxxxx
From: akpm@xxxxxxxxxxxxxxxxxxxx
Date: Fri, 22 Nov 2013 15:53:45 -0800
The patch titled
Subject: mm/hugetlb.c: call MMU notifiers when copying a hugetlb page range
has been added to the -mm tree. Its filename is
mm-call-mmu-notifiers-when-copying-a-hugetlb-page-range.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-call-mmu-notifiers-when-copying-a-hugetlb-page-range.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-call-mmu-notifiers-when-copying-a-hugetlb-page-range.patch
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------------------------------------------------------
From: Andreas Sandberg <andreas@xxxxxxxxxxxxxx>
Subject: mm/hugetlb.c: call MMU notifiers when copying a hugetlb page range
When copy_hugetlb_page_range() is called to copy a range of hugetlb
mappings, the secondary MMUs are not notified if there is a protection
downgrade, which breaks COW semantics in KVM.
This patch adds the necessary MMU notifier calls.
Signed-off-by: Andreas Sandberg <andreas@xxxxxxxxxxxxxx>
Acked-by: Steve Capper <steve.capper@xxxxxxxxxx>
Acked-by: Marc Zyngier <marc.zyngier@xxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/hugetlb.c | 21 ++++++++++++++++-----
1 file changed, 16 insertions(+), 5 deletions(-)
diff -puN mm/hugetlb.c~mm-call-mmu-notifiers-when-copying-a-hugetlb-page-range mm/hugetlb.c
--- a/mm/hugetlb.c~mm-call-mmu-notifiers-when-copying-a-hugetlb-page-range
+++ a/mm/hugetlb.c
@@ -2346,17 +2346,27 @@ int copy_hugetlb_page_range(struct mm_st
int cow;
struct hstate *h = hstate_vma(vma);
unsigned long sz = huge_page_size(h);
+ unsigned long mmun_start; /* For mmu_notifiers */
+ unsigned long mmun_end; /* For mmu_notifiers */
+ int ret = 0;
cow = (vma->vm_flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE;
+ mmun_start = vma->vm_start;
+ mmun_end = vma->vm_end;
+ if (cow)
+ mmu_notifier_invalidate_range_start(src, mmun_start, mmun_end);
+
for (addr = vma->vm_start; addr < vma->vm_end; addr += sz) {
spinlock_t *src_ptl, *dst_ptl;
src_pte = huge_pte_offset(src, addr);
if (!src_pte)
continue;
dst_pte = huge_pte_alloc(dst, addr, sz);
- if (!dst_pte)
- goto nomem;
+ if (!dst_pte) {
+ ret = -ENOMEM;
+ break;
+ }
/* If the pagetables are shared don't copy or take references */
if (dst_pte == src_pte)
@@ -2377,10 +2387,11 @@ int copy_hugetlb_page_range(struct mm_st
spin_unlock(src_ptl);
spin_unlock(dst_ptl);
}
- return 0;
-nomem:
- return -ENOMEM;
+ if (cow)
+ mmu_notifier_invalidate_range_end(src, mmun_start, mmun_end);
+
+ return ret;
}
static int is_hugetlb_entry_migration(pte_t pte)
_
Patches currently in -mm which might be from andreas@xxxxxxxxxxxxxx are
mm-call-mmu-notifiers-when-copying-a-hugetlb-page-range.patch
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