mm/mremap: fix unaccount of memory on vma_merge() failure

Fix mremap so that only accounted memory is unaccounted if the mapping is
expandable but vma_merge() fails.

Link: https://lkml.kernel.org/r/20230830004549.16131-1-anthony.yznaga@oracle.com
Fixes: fdbef6149135 ("mm/mremap: don't account pages in vma_to_resize()")
Signed-off-by: Anthony Yznaga <anthony.yznaga@oracle.com>
Acked-by: Brian Geffon <bgeffon@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/mremap.c b/mm/mremap.c
index 382e81c33fc437f2e11e49a1f8a7d68e99e5c845..fbb4861964f6701b9a0e1886107109875a936fc4 100644 (file)
--- a/mm/mremap.c
+++ b/mm/mremap.c
@@ -1037,12 +1037,14 @@ SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len,
                        pgoff_t extension_pgoff = vma->vm_pgoff +
                                ((extension_start - vma->vm_start) >> PAGE_SHIFT);
                        VMA_ITERATOR(vmi, mm, extension_start);
+                       long charged = 0;
 
                        if (vma->vm_flags & VM_ACCOUNT) {
                                if (security_vm_enough_memory_mm(mm, pages)) {
                                        ret = -ENOMEM;
                                        goto out;
                                }
+                               charged = pages;
                        }
 
                        /*
@@ -1058,7 +1060,7 @@ SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len,
                                vma->vm_file, extension_pgoff, vma_policy(vma),
                                vma->vm_userfaultfd_ctx, anon_vma_name(vma));
                        if (!vma) {
-                               vm_unacct_memory(pages);
+                               vm_unacct_memory(charged);
                                ret = -ENOMEM;
                                goto out;
                        }