On Mon, Jul 07, 2014 at 06:33:38PM -0700, Hugh Dickins wrote:
> On Mon, 7 Jul 2014, gregkh@xxxxxxxxxxxxxxxxxxx wrote:
>
> >
> > The patch below does not apply to the 3.10-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 3.10.48 ------------------
>
Thanks! I'm using this backport for the 3.11 kernel as well.
Cheers,
--
Luís
> 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
> @@ -608,19 +608,18 @@ static unsigned long change_prot_numa(st
> * 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) {
> unsigned long endvma = vma->vm_end;
>
> if (endvma > end)
> @@ -630,9 +629,9 @@ check_range(struct mm_struct *mm, unsign
>
> 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))
> @@ -649,15 +648,13 @@ check_range(struct mm_struct *mm, unsign
>
> err = check_pgd_range(vma, start, endvma, nodes,
> flags, private);
> - if (err) {
> - first = ERR_PTR(err);
> + if (err)
> break;
> - }
> }
> next:
> prev = vma;
> }
> - return first;
> + return err;
> }
>
> /*
> @@ -1138,16 +1135,17 @@ 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)
> @@ -1173,7 +1171,7 @@ 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;
> }
> @@ -1183,7 +1181,6 @@ 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;
> @@ -1249,11 +1246,9 @@ 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); /* maybe ... */
> - if (!IS_ERR(vma))
> + if (!err)
> err = mbind_range(mm, start, end, new);
>
> if (!err) {
> @@ -1261,9 +1256,8 @@ static long do_mbind(unsigned long start
>
> if (!list_empty(&pagelist)) {
> WARN_ON_ONCE(flags & MPOL_MF_LAZY);
> - nr_failed = migrate_pages(&pagelist, new_vma_page,
> - (unsigned long)vma,
> - MIGRATE_SYNC, MR_MEMPOLICY_MBIND);
> + nr_failed = migrate_pages(&pagelist, new_page,
> + start, MIGRATE_SYNC, MR_MEMPOLICY_MBIND);
> if (nr_failed)
> putback_lru_pages(&pagelist);
> }
> --
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