mremap will account the delta between new_len and old_len in
vma_to_resize, and then call move_vma when expanding an existing
memory mapping. In function move_vma, there are two scenarios when
calling do_munmap:
1. move_page_tables from old_addr to new_addr success
2. move_page_tables from old_addr to new_addr fail
In first scenario, it should account old_len if do_munmap fail,
because the delta has already been accounted.
In second scenario, new_addr/new_len will assign to old_addr/old_len
if move_page_table fail, so do_munmap is try to unmap new_addr actually,
if do_munmap fail, it should account the new_len, because error code
will be return from move_vma, and delta will be unaccounted.
What'more, because of new_len == old_len, so account old_len also is
OK.
In summary, account old_len will be correct if do_munmap fail.
Fixes: 51df7bcb6151 ("mm/mremap: account memory on do_munmap() failure")
Signed-off-by: Chen Wandun <chenwandun@xxxxxxxxxx>
---
mm/mremap.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/mm/mremap.c b/mm/mremap.c
index 5989d3990020..badfe17ade1f 100644
--- a/mm/mremap.c
+++ b/mm/mremap.c
@@ -686,7 +686,7 @@ static unsigned long move_vma(struct vm_area_struct *vma,
if (do_munmap(mm, old_addr, old_len, uf_unmap) < 0) {
/* OOM: unable to split vma, just get accounts right */
if (vm_flags & VM_ACCOUNT && !(flags & MREMAP_DONTUNMAP))
- vm_acct_memory(new_len >> PAGE_SHIFT);
+ vm_acct_memory(old_len >> PAGE_SHIFT);
excess = 0;
}
--
2.25.1
