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mm: revert mremap pud_free anti-fix 

Revert commit 1ecfd533f4 ("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 1ecfd533f4 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>
This commit is contained in:
Hugh Dickins 2013-10-16 13:47:09 -07:00 committed by Linus Torvalds
parent 750e8165f5
commit 57a8f0cdb8
1 changed files with 1 additions and 4 deletions
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5
mm/mremap.c
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@ -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));