mremap() is modifying the VMA layout and thus must be protected against
the speculative page fault handler.
XXX: Is the change to vma->vm_flags to set VM_ACCOUNT require the
protection ?
Signed-off-by: Laurent Dufour <ldufour@xxxxxxxxxxxxxxxxxx>
---
mm/mremap.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/mm/mremap.c b/mm/mremap.c
index 30d7d2482eea..40c3c869dffc 100644
--- a/mm/mremap.c
+++ b/mm/mremap.c
@@ -288,6 +288,10 @@ static unsigned long move_vma(struct vm_area_struct *vma,
if (!new_vma)
return -ENOMEM;
+ write_seqcount_begin(&vma->vm_sequence);
+ write_seqcount_begin_nested(&new_vma->vm_sequence,
+ SINGLE_DEPTH_NESTING);
+
moved_len = move_page_tables(vma, old_addr, new_vma, new_addr, old_len,
need_rmap_locks);
if (moved_len < old_len) {
@@ -304,6 +308,7 @@ static unsigned long move_vma(struct vm_area_struct *vma,
*/
move_page_tables(new_vma, new_addr, vma, old_addr, moved_len,
true);
+ write_seqcount_end(&vma->vm_sequence);
vma = new_vma;
old_len = new_len;
old_addr = new_addr;
@@ -311,7 +316,9 @@ static unsigned long move_vma(struct vm_area_struct *vma,
} else {
arch_remap(mm, old_addr, old_addr + old_len,
new_addr, new_addr + new_len);
+ write_seqcount_end(&vma->vm_sequence);
}
+ write_seqcount_end(&new_vma->vm_sequence);
/* Conceal VM_ACCOUNT so old reservation is not undone */
if (vm_flags & VM_ACCOUNT) {
--
2.7.4
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