On Mon, 7 Jul 2014, gregkh@xxxxxxxxxxxxxxxxxxx wrote:
>
> The patch below does not apply to the 3.4-stable tree.
> If someone wants it applied there, or to any other stable or longterm
> tree, then please email the backport, including the original git commit
> id to <stable@xxxxxxxxxxxxxxx>.
>
> thanks,
>
> greg k-h
>
------------------ version for 3.4.98 ------------------
>From d05f0cdcbe6388723f1900c549b4850360545201 Mon Sep 17 00:00:00 2001
From: Hugh Dickins <hughd@xxxxxxxxxx>
Date: Mon, 23 Jun 2014 13:22:07 -0700
Subject: [PATCH] mm: fix crashes from mbind() merging vmas
In v2.6.34 commit 9d8cebd4bcd7 ("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: 9d8cebd4bcd7 ("mm: fix mbind vma merge problem")
Reported-by: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
Tested-by: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
Signed-off-by: Hugh Dickins <hughd@xxxxxxxxxx>
Acked-by: Christoph Lameter <cl@xxxxxxxxx>
Cc: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx>
Cc: Minchan Kim <minchan.kim@xxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx> [2.6.34+]
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -566,24 +566,24 @@ static inline int check_pgd_range(struct
* If pagelist != NULL then isolate pages from the LRU and
* put them on the pagelist.
*/
-static struct vm_area_struct *
+static int
check_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) {
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 (!is_vm_hugetlb_page(vma) &&
((flags & MPOL_MF_STRICT) ||
@@ -597,14 +597,12 @@ check_range(struct mm_struct *mm, unsign
start = vma->vm_start;
err = check_pgd_range(vma, start, endvma, nodes,
flags, private);
- if (err) {
- first = ERR_PTR(err);
+ if (err)
break;
- }
}
prev = vma;
}
- return first;
+ return err;
}
/*
@@ -945,16 +943,15 @@ static int migrate_to_node(struct mm_str
{
nodemask_t nmask;
LIST_HEAD(pagelist);
- int err = 0;
- struct vm_area_struct *vma;
+ int err;
nodes_clear(nmask);
node_set(source, nmask);
- vma = check_range(mm, mm->mmap->vm_start, mm->task_size, &nmask,
+ err = check_range(mm, mm->mmap->vm_start, mm->task_size, &nmask,
flags | MPOL_MF_DISCONTIG_OK, &pagelist);
- if (IS_ERR(vma))
- return PTR_ERR(vma);
+ if (err)
+ return err;
if (!list_empty(&pagelist)) {
err = migrate_pages(&pagelist, new_node_page, dest,
@@ -1058,16 +1055,17 @@ 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)
@@ -1093,7 +1091,7 @@ int do_migrate_pages(struct mm_struct *m
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;
}
@@ -1103,7 +1101,6 @@ static long do_mbind(unsigned long start
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;
@@ -1167,19 +1164,17 @@ static long do_mbind(unsigned long start
if (err)
goto mpol_out;
- vma = check_range(mm, start, end, nmask,
+ err = check_range(mm, start, end, nmask,
flags | MPOL_MF_INVERT, &pagelist);
- err = PTR_ERR(vma);
- if (!IS_ERR(vma)) {
+ if (!err) {
int nr_failed = 0;
err = mbind_range(mm, start, end, new);
if (!list_empty(&pagelist)) {
- nr_failed = migrate_pages(&pagelist, new_vma_page,
- (unsigned long)vma,
- false, true);
+ nr_failed = migrate_pages(&pagelist, new_page,
+ start, false, true);
if (nr_failed)
putback_lru_pages(&pagelist);
}
--
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