mm: fix apply_to_existing_page_range()

commit a995199384347261bb3f21b2e171fa7f988bd2f8 upstream.

In the case of apply_to_existing_page_range(), apply_to_pte_range() is
reached with 'create' set to false.  When !create, the loop over the PTE
page table is broken.

apply_to_pte_range() will only move to the next PTE entry if 'create' is
true or if the current entry is not pte_none().

This means that the user of apply_to_existing_page_range() will not have
'fn' called for any entries after the first pte_none() in the PTE page
table.

Fix the loop logic in apply_to_pte_range().

There are no known runtime issues from this, but the fix is trivial enough
for stable@ even without a known buggy user.

Link: https://lkml.kernel.org/r/20250409094043.1629234-1-kirill.shutemov@linux.intel.com
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Fixes: be1db4753ee6 ("mm/memory.c: add apply_to_existing_page_range() helper")
Cc: Daniel Axtens <dja@axtens.net>
Cc: David Hildenbrand <david@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/mm/memory.c b/mm/memory.c
index 99dceaf6a10579022dfafb2dcb12dfad79dce171..b6daa0e673a54958b9c95f29d63371ae2bdea02c 100644 (file)
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2811,11 +2811,11 @@ static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd,
        if (fn) {
                do {
                        if (create || !pte_none(ptep_get(pte))) {
-                               err = fn(pte++, addr, data);
+                               err = fn(pte, addr, data);
                                if (err)
                                        break;
                        }
-               } while (addr += PAGE_SIZE, addr != end);
+               } while (pte++, addr += PAGE_SIZE, addr != end);
        }
        *mask |= PGTBL_PTE_MODIFIED;