This patch fixes the warning about mmun_start/end used uninitialized in
copy_page_range, by initializing them regardless of whether the notifiers are
actually called. It also makes sure the vm_flags in copy_page_range are only
read once.
Cc: Minchan Kim <minchan@xxxxxxxxxx>
Signed-off-by: Haggai Eran <haggaie@xxxxxxxxxxxx>
---
mm/memory.c | 13 +++++++------
1 file changed, 7 insertions(+), 6 deletions(-)
diff --git a/mm/memory.c b/mm/memory.c
index 3c88368..423d214 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -712,7 +712,7 @@ static void print_bad_pte(struct vm_area_struct *vma, unsigned long addr,
add_taint(TAINT_BAD_PAGE);
}
-static inline int is_cow_mapping(vm_flags_t flags)
+static inline bool is_cow_mapping(vm_flags_t flags)
{
return (flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE;
}
@@ -1041,6 +1041,7 @@ int copy_page_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
unsigned long end = vma->vm_end;
unsigned long mmun_start; /* For mmu_notifiers */
unsigned long mmun_end; /* For mmu_notifiers */
+ bool is_cow;
int ret;
/*
@@ -1073,12 +1074,12 @@ int copy_page_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
* parent mm. And a permission downgrade will only happen if
* is_cow_mapping() returns true.
*/
- if (is_cow_mapping(vma->vm_flags)) {
- mmun_start = addr;
- mmun_end = end;
+ is_cow = is_cow_mapping(vma->vm_flags);
+ mmun_start = addr;
+ mmun_end = end;
+ if (is_cow)
mmu_notifier_invalidate_range_start(src_mm, mmun_start,
mmun_end);
- }
ret = 0;
dst_pgd = pgd_offset(dst_mm, addr);
@@ -1094,7 +1095,7 @@ int copy_page_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
}
} while (dst_pgd++, src_pgd++, addr = next, addr != end);
- if (is_cow_mapping(vma->vm_flags))
+ if (is_cow)
mmu_notifier_invalidate_range_end(src_mm, mmun_start,
mmun_end);
return ret;
--
1.7.11.2
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