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authorAndreas Sandberg <andreas@sandberg.pp.se>2014-01-21 15:49:09 -0800
committerMark Brown <broonie@linaro.org>2014-05-09 12:02:47 +0100
commit89a6a78ec21e274c8abe1a63f2abc876ba127b60 (patch)
treeb4e58dc166ef0e414f8e30a95491d4b1ba696173
parent7e5f0d41d30d8914400e0e4b892bc25b19cd38f1 (diff)
downloadlinux-linaro-stable-89a6a78ec21e274c8abe1a63f2abc876ba127b60.tar.gz
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@sandberg.pp.se> Acked-by: Steve Capper <steve.capper@linaro.org> Acked-by: Marc Zyngier <marc.zyngier@arm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Rik van Riel <riel@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--mm/hugetlb.c21
1 files changed, 16 insertions, 5 deletions
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index dbd3d42ae031..a7482d1d2131 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -2295,16 +2295,26 @@ int copy_hugetlb_page_range(struct mm_struct *dst, struct mm_struct *src,
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) {
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)
@@ -2324,10 +2334,11 @@ int copy_hugetlb_page_range(struct mm_struct *dst, struct mm_struct *src,
spin_unlock(&src->page_table_lock);
spin_unlock(&dst->page_table_lock);
}
- 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)