mm: revert mremap pud_free anti-fix

Revert commit 1ecfd533f4c5 ("mm/mremap.c: call pud_free() after fail
calling pmd_alloc()").

The original code was correct: pud_alloc(), pmd_alloc(), pte_alloc_map()
ensure that the pud, pmd, pt is already allocated, and seldom do they
need to allocate; on failure, upper levels are freed if appropriate by
the subsequent do_munmap().  Whereas commit 1ecfd533f4c5 did an
unconditional pud_free() of a most-likely still-in-use pud: saved only
by the near-impossiblity of pmd_alloc() failing.

Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: Chen Gang <gang.chen@asianux.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/mremap.c b/mm/mremap.c
index 91b13d6a16d453b50894e6028800b92399bf8f14..0843feb66f3d0236abd4386b5bfd0170c24ae0ef 100644 (file)
--- a/mm/mremap.c
+++ b/mm/mremap.c
@@ -25,7 +25,6 @@
 #include <asm/uaccess.h>
 #include <asm/cacheflush.h>
 #include <asm/tlbflush.h>
-#include <asm/pgalloc.h>
 
 #include "internal.h"
 
@@ -63,10 +62,8 @@ static pmd_t *alloc_new_pmd(struct mm_struct *mm, struct vm_area_struct *vma,
                return NULL;
 
        pmd = pmd_alloc(mm, pud, addr);
-       if (!pmd) {
-               pud_free(mm, pud);
+       if (!pmd)
                return NULL;
-       }
 
        VM_BUG_ON(pmd_trans_huge(*pmd));