On Wed, Aug 20, 2008 at 11:05:15PM -0400, Oren Laadan wrote:
>
> For each VMA, there is a 'struct cr_vma'; if the VMA is file-mapped,
> it will be followed by the file name.  The cr_vma->npages will tell
> how many pages were dumped for this VMA.  Then it will be followed
> by the actual data: first a dump of the addresses of all dumped
> pages (npages entries) followed by a dump of the contents of all
> dumped pages (npages pages). Then will come the next VMA and so on.

[...]

> diff --git a/checkpoint/ckpt_mem.c b/checkpoint/ckpt_mem.c
> new file mode 100644
> index 0000000..a23aa29
> --- /dev/null
> +++ b/checkpoint/ckpt_mem.c

[...]

> +/**
> + * cr_vma_fill_pgarr - fill a page-array with addr/page tuples for a vma
> + * @ctx - checkpoint context
> + * @pgarr - page-array to fill
> + * @vma - vma to scan
> + * @start - start address (updated)
> + */
> +static int cr_vma_fill_pgarr(struct cr_ctx *ctx, struct cr_pgarr *pgarr,
> +                          struct vm_area_struct *vma, unsigned long *start)
> +{
> +     unsigned long end = vma->vm_end;
> +     unsigned long addr = *start;
> +     struct page **pagep;
> +     unsigned long *addrp;
> +     int cow, nr, ret = 0;
> +
> +     nr = pgarr->nleft;
> +     pagep = &pgarr->pages[pgarr->nused];
> +     addrp = &pgarr->addrs[pgarr->nused];
> +     cow = !!vma->vm_file;
> +
> +     while (addr < end) {
> +             struct page *page;
> +
> +             /* simplified version of get_user_pages(): already have vma,
> +             * only need FOLL_TOUCH, and (for now) ignore fault stats */
> +
> +             cond_resched();
> +             while (!(page = follow_page(vma, addr, FOLL_TOUCH))) {
> +                     ret = handle_mm_fault(vma->vm_mm, vma, addr, 0);
> +                     if (ret & VM_FAULT_ERROR) {
> +                             if (ret & VM_FAULT_OOM)
> +                                     ret = -ENOMEM;
> +                             else if (ret & VM_FAULT_SIGBUS)
> +                                     ret = -EFAULT;
> +                             else
> +                                     BUG();
> +                             break;
> +                     }

+                       ret = 0;

> +                     cond_resched();
> +             }
> +
> +             if (IS_ERR(page)) {
> +                     ret = PTR_ERR(page);
> +                     break;
> +             }

Need to check ret here:

+               if (ret)
                        break;

> +
> +             if (page == ZERO_PAGE(0))
> +                     page = NULL;    /* zero page: ignore */
> +             else if (cow && page_mapping(page) != NULL)
> +                     page = NULL;    /* clean cow: ignore */
> +             else {
> +                     get_page(page);
> +                     *(addrp++) = addr;
> +                     *(pagep++) = page;
> +                     if (--nr == 0) {
> +                             addr += PAGE_SIZE;
> +                             break;
> +                     }
> +             }
> +
> +             addr += PAGE_SIZE;
> +     }
> +
> +     if (unlikely(ret < 0)) {
> +             nr = pgarr->nleft - nr;
> +             while (nr--)
> +                     page_cache_release(*(--pagep));
> +             return ret;
> +     }
> +
> +     *start = addr;
> +     return (pgarr->nleft - nr);
> +}

[...]

Thanks,

Louis

-- 
Dr Louis Rilling                        Kerlabs
Skype: louis.rilling                    Batiment Germanium
Phone: (+33|0) 6 80 89 08 23            80 avenue des Buttes de Coesmes
http://www.kerlabs.com/                 35700 Rennes

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