[CRIU] [PATCH 2/3]v2 mem: if no parent image persists, can't rely on it

[Pavel Tikhomirov]

Pls, watch patch


Best Regards, Tikhomirov Pavel.


2014-04-16 17:05 GMT+04:00 Tikhomirov Pavel <snorcht at gmail.com>:

> here was bug cause if e.g.: iterative snapshots are made and
> between two of them new process in process tree was created,
> it can have pages which are non dirty, and won't save them
> into image. but there is no parent image for it.
>
> pages which are non soft-dirty appear if process with some pages
> in non dirty state forks, child will inherit those pte's
> and if child don't write to those pages, they will be still in non
> soft-dirty state when next dump comes.
>
> also this bug was not catched because of error in zdtm, look 3/3
>
> v2: simplify, add more justification in commit message.
>
> Signed-off-by: Tikhomirov Pavel <snorcht at gmail.com>
> ---
>  mem.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/mem.c b/mem.c
> index ef1d010..46dee60 100644
> --- a/mem.c
> +++ b/mem.c
> @@ -106,7 +106,7 @@ static inline bool page_in_parent(u64 pme)
>   * the memory contents is present in the pagent image set.
>   */
>
> -static int generate_iovs(struct vma_area *vma, struct page_pipe *pp, u64
> *map, u64 *off)
> +static int generate_iovs(struct vma_area *vma, struct page_pipe *pp, u64
> *map, u64 *off, bool parent)
>  {
>         u64 *at = &map[PAGE_PFN(*off)];
>         unsigned long pfn, nr_to_scan;
> @@ -130,7 +130,7 @@ static int generate_iovs(struct vma_area *vma, struct
> page_pipe *pp, u64 *map, u
>                  * page. The latter would be checked in page-xfer.
>                  */
>
> -               if (page_in_parent(at[pfn])) {
> +               if (page_in_parent(at[pfn]) && parent) {
>                         ret = page_pipe_add_hole(pp, vaddr);
>                         pages[0]++;
>                 } else {
> @@ -282,7 +282,7 @@ static int __parasite_dump_pages_seized(struct
> parasite_ctl *ctl,
>                 if (!map)
>                         goto out_xfer;
>  again:
> -               ret = generate_iovs(vma_area, pp, map, &off);
> +               ret = generate_iovs(vma_area, pp, map, &off, xfer.parent);
>                 if (ret == -EAGAIN) {
>                         BUG_ON(pp_ret);
>
> --
> 1.8.3.2
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.openvz.org/pipermail/criu/attachments/20140418/4f93de67/attachment.html>