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Subject[PATCH] mm: revert mremap pud_free anti-fix
Revert 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 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>
---

mm/mremap.c | 5 +----
1 file changed, 1 insertion(+), 4 deletions(-)

--- 3.12-rc5/mm/mremap.c 2013-09-16 17:37:56.841072270 -0700
+++ linux/mm/mremap.c 2013-10-15 03:07:09.140091599 -0700
@@ -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_st
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));


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