Commit d05f0cdc authored by Hugh Dickins's avatar Hugh Dickins Committed by Linus Torvalds
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mm: fix crashes from mbind() merging vmas

In v2.6.34 commit 9d8cebd4 ("mm: fix mbind vma merge problem")
introduced vma merging to mbind(), but it should have also changed the
convention of passing start vma from queue_pages_range() (formerly
check_range()) to new_vma_page(): vma merging may have already freed
that structure, resulting in BUG at mm/mempolicy.c:1738 and probably
worse crashes.

Fixes: 9d8cebd4

 ("mm: fix mbind vma merge problem")
Reported-by: default avatarNaoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Tested-by: default avatarNaoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: default avatarHugh Dickins <hughd@google.com>
Acked-by: default avatarChristoph Lameter <cl@linux.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Minchan Kim <minchan.kim@gmail.com>
Cc: <stable@vger.kernel.org>	[2.6.34+]
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent b43ae21b
......@@ -656,19 +656,18 @@ static unsigned long change_prot_numa(struct vm_area_struct *vma,
* @nodes and @flags,) it's isolated and queued to the pagelist which is
* passed via @private.)
*/
static struct vm_area_struct *
static int
queue_pages_range(struct mm_struct *mm, unsigned long start, unsigned long end,
const nodemask_t *nodes, unsigned long flags, void *private)
{
int err;
struct vm_area_struct *first, *vma, *prev;
int err = 0;
struct vm_area_struct *vma, *prev;
first = find_vma(mm, start);
if (!first)
return ERR_PTR(-EFAULT);
vma = find_vma(mm, start);
if (!vma)
return -EFAULT;
prev = NULL;
for (vma = first; vma && vma->vm_start < end; vma = vma->vm_next) {
for (; vma && vma->vm_start < end; vma = vma->vm_next) {
unsigned long endvma = vma->vm_end;
if (endvma > end)
......@@ -678,9 +677,9 @@ queue_pages_range(struct mm_struct *mm, unsigned long start, unsigned long end,
if (!(flags & MPOL_MF_DISCONTIG_OK)) {
if (!vma->vm_next && vma->vm_end < end)
return ERR_PTR(-EFAULT);
return -EFAULT;
if (prev && prev->vm_end < vma->vm_start)
return ERR_PTR(-EFAULT);
return -EFAULT;
}
if (flags & MPOL_MF_LAZY) {
......@@ -694,15 +693,13 @@ queue_pages_range(struct mm_struct *mm, unsigned long start, unsigned long end,
err = queue_pages_pgd_range(vma, start, endvma, nodes,
flags, private);
if (err) {
first = ERR_PTR(err);
if (err)
break;
}
}
next:
prev = vma;
}
return first;
return err;
}
/*
......@@ -1156,16 +1153,17 @@ out:
/*
* Allocate a new page for page migration based on vma policy.
* Start assuming that page is mapped by vma pointed to by @private.
* Start by assuming the page is mapped by the same vma as contains @start.
* Search forward from there, if not. N.B., this assumes that the
* list of pages handed to migrate_pages()--which is how we get here--
* is in virtual address order.
*/
static struct page *new_vma_page(struct page *page, unsigned long private, int **x)
static struct page *new_page(struct page *page, unsigned long start, int **x)
{
struct vm_area_struct *vma = (struct vm_area_struct *)private;
struct vm_area_struct *vma;
unsigned long uninitialized_var(address);
vma = find_vma(current->mm, start);
while (vma) {
address = page_address_in_vma(page, vma);
if (address != -EFAULT)
......@@ -1195,7 +1193,7 @@ int do_migrate_pages(struct mm_struct *mm, const nodemask_t *from,
return -ENOSYS;
}
static struct page *new_vma_page(struct page *page, unsigned long private, int **x)
static struct page *new_page(struct page *page, unsigned long start, int **x)
{
return NULL;
}
......@@ -1205,7 +1203,6 @@ static long do_mbind(unsigned long start, unsigned long len,
unsigned short mode, unsigned short mode_flags,
nodemask_t *nmask, unsigned long flags)
{
struct vm_area_struct *vma;
struct mm_struct *mm = current->mm;
struct mempolicy *new;
unsigned long end;
......@@ -1271,11 +1268,9 @@ static long do_mbind(unsigned long start, unsigned long len,
if (err)
goto mpol_out;
vma = queue_pages_range(mm, start, end, nmask,
err = queue_pages_range(mm, start, end, nmask,
flags | MPOL_MF_INVERT, &pagelist);
err = PTR_ERR(vma); /* maybe ... */
if (!IS_ERR(vma))
if (!err)
err = mbind_range(mm, start, end, new);
if (!err) {
......@@ -1283,9 +1278,8 @@ static long do_mbind(unsigned long start, unsigned long len,
if (!list_empty(&pagelist)) {
WARN_ON_ONCE(flags & MPOL_MF_LAZY);
nr_failed = migrate_pages(&pagelist, new_vma_page,
NULL, (unsigned long)vma,
MIGRATE_SYNC, MR_MEMPOLICY_MBIND);
nr_failed = migrate_pages(&pagelist, new_page, NULL,
start, MIGRATE_SYNC, MR_MEMPOLICY_MBIND);
if (nr_failed)
putback_movable_pages(&pagelist);
}
......
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