On Sun, Sep 14, 2008 at 8:06 AM, Oren Laadan <orenl@cs.columbia.edu> wrote:
quoted text
> For each VMA, there is a 'struct cr_vma'; if the VMA is file-mapped,
> it will be followed by the file name. Then comes the actual contents,
> in one or more chunk: each chunk begins with a header that specifies
> how many pages it holds, then the virtual addresses of all the dumped
> pages in that chunk, followed by the actual contents of all dumped
> pages. A header with zero number of pages marks the end of the contents.
> Then comes the next VMA and so on.
>
> Signed-off-by: Oren Laadan <orenl@cs.columbia.edu>
> ---
>  arch/x86/mm/checkpoint.c         |   30 +++
>  arch/x86/mm/restart.c            |    1 +
>  checkpoint/Makefile              |    3 +-
>  checkpoint/checkpoint.c          |   53 ++++
>  checkpoint/checkpoint_arch.h     |    2 +
>  checkpoint/checkpoint_mem.h      |   41 ++++
>  checkpoint/ckpt_mem.c            |  492 ++++++++++++++++++++++++++++++++++++++
>  checkpoint/sys.c                 |   27 ++-
>  include/asm-x86/checkpoint_hdr.h |    5 +
>  include/linux/checkpoint.h       |   12 +
>  include/linux/checkpoint_hdr.h   |   32 +++
>  11 files changed, 692 insertions(+), 6 deletions(-)
>  create mode 100644 checkpoint/checkpoint_mem.h
>  create mode 100644 checkpoint/ckpt_mem.c
>
> diff --git a/arch/x86/mm/checkpoint.c b/arch/x86/mm/checkpoint.c
> index eb60003..fa87e4a 100644
> --- a/arch/x86/mm/checkpoint.c
> +++ b/arch/x86/mm/checkpoint.c
> @@ -196,3 +196,33 @@ int cr_write_cpu(struct cr_ctx *ctx, struct task_struct *t)
>        cr_hbuf_put(ctx, sizeof(*hh));
>        return ret;
>  }
> +
> +/* dump the mm->context state */
> +int cr_write_mm_context(struct cr_ctx *ctx, struct mm_struct *mm, int parent)
> +{
> +       struct cr_hdr h;
> +       struct cr_hdr_mm_context *hh = cr_hbuf_get(ctx, sizeof(*hh));
> +       int ret;
> +
> +       h.type = CR_HDR_MM_CONTEXT;
> +       h.len = sizeof(*hh);
> +       h.parent = parent;
> +
> +       mutex_lock(&mm->context.lock);
> +
> +       hh->ldt_entry_size = LDT_ENTRY_SIZE;
> +       hh->nldt = mm->context.size;
> +
> +       cr_debug("nldt %d\n", hh->nldt);
> +
> +       ret = cr_write_obj(ctx, &h, hh);
> +       cr_hbuf_put(ctx, sizeof(*hh));
> +       if (ret < 0)
> +               goto out;
> +
> +       ret = cr_kwrite(ctx, mm->context.ldt, hh->nldt * LDT_ENTRY_SIZE);
> +
> + out:
> +       mutex_unlock(&mm->context.lock);
> +       return ret;
> +}
> diff --git a/arch/x86/mm/restart.c b/arch/x86/mm/restart.c
> index 0178080..79780df 100644
> --- a/arch/x86/mm/restart.c
> +++ b/arch/x86/mm/restart.c
> @@ -8,6 +8,7 @@
>  *  distribution for more details.
>  */
>
> +#include <linux/unistd.h>
>  #include <asm/desc.h>
>  #include <asm/i387.h>
>
> diff --git a/checkpoint/Makefile b/checkpoint/Makefile
> index d2df68c..3a0df6d 100644
> --- a/checkpoint/Makefile
> +++ b/checkpoint/Makefile
> @@ -2,4 +2,5 @@
>  # Makefile for linux checkpoint/restart.
>  #
>
> -obj-$(CONFIG_CHECKPOINT_RESTART) += sys.o checkpoint.o restart.o
> +obj-$(CONFIG_CHECKPOINT_RESTART) += sys.o checkpoint.o restart.o \
> +               ckpt_mem.o
> diff --git a/checkpoint/checkpoint.c b/checkpoint/checkpoint.c
> index 6ca26d0..d4c1b31 100644
> --- a/checkpoint/checkpoint.c
> +++ b/checkpoint/checkpoint.c
> @@ -55,6 +55,55 @@ int cr_write_string(struct cr_ctx *ctx, char *str, int len)
>        return cr_write_obj(ctx, &h, str);
>  }
>
> +/**
> + * cr_fill_fname - return pathname of a given file
> + * @path: path name
> + * @root: relative root
> + * @buf: buffer for pathname
> + * @n: buffer length (in) and pathname length (out)
> + */
> +static char *
> +cr_fill_fname(struct path *path, struct path *root, char *buf, int *n)
> +{
> +       char *fname;
> +
> +       BUG_ON(!buf);
> +       fname = __d_path(path, root, buf, *n);
> +       if (!IS_ERR(fname))
> +               *n = (buf + (*n) - fname);
> +       return fname;
> +}
> +
> +/**
> + * cr_write_fname - write a file name
> + * @ctx: checkpoint context
> + * @path: path name
> + * @root: relative root
> + */
> +int cr_write_fname(struct cr_ctx *ctx, struct path *path, struct path *root)
> +{
> +       struct cr_hdr h;
> +       char *buf, *fname;
> +       int ret, flen;
> +
> +       flen = PATH_MAX;
> +       buf = kmalloc(flen, GFP_KERNEL);
> +       if (!buf)
> +               return -ENOMEM;
> +
> +       fname = cr_fill_fname(path, root, buf, &flen);
> +       if (!IS_ERR(fname)) {
> +               h.type = CR_HDR_FNAME;
> +               h.len = flen;
> +               h.parent = 0;
> +               ret = cr_write_obj(ctx, &h, fname);
> +       } else
> +               ret = PTR_ERR(fname);
> +
> +       kfree(buf);
> +       return ret;
> +}
> +
>  /* write the checkpoint header */
>  static int cr_write_head(struct cr_ctx *ctx)
>  {
> @@ -150,6 +199,10 @@ static int cr_write_task(struct cr_ctx *ctx, struct task_struct *t)
>        cr_debug("task_struct: ret %d\n", ret);
>        if (ret < 0)
>                goto out;
> +       ret = cr_write_mm(ctx, t);
> +       cr_debug("memory: ret %d\n", ret);
> +       if (ret < 0)
> +               goto out;
>        ret = cr_write_thread(ctx, t);
>        cr_debug("thread: ret %d\n", ret);
>        if (ret < 0)
> diff --git a/checkpoint/checkpoint_arch.h b/checkpoint/checkpoint_arch.h
> index bf2d21e..7da4ad0 100644
> --- a/checkpoint/checkpoint_arch.h
> +++ b/checkpoint/checkpoint_arch.h
> @@ -2,6 +2,8 @@
>
>  extern int cr_write_thread(struct cr_ctx *ctx, struct task_struct *t);
>  extern int cr_write_cpu(struct cr_ctx *ctx, struct task_struct *t);
> +extern int cr_write_mm_context(struct cr_ctx *ctx,
> +                              struct mm_struct *mm, int parent);
>
>  extern int cr_read_thread(struct cr_ctx *ctx);
>  extern int cr_read_cpu(struct cr_ctx *ctx);
> diff --git a/checkpoint/checkpoint_mem.h b/checkpoint/checkpoint_mem.h
> new file mode 100644
> index 0000000..85546f4
> --- /dev/null
> +++ b/checkpoint/checkpoint_mem.h
> @@ -0,0 +1,41 @@
> +#ifndef _CHECKPOINT_CKPT_MEM_H_
> +#define _CHECKPOINT_CKPT_MEM_H_
> +/*
> + *  Generic container checkpoint-restart
> + *
> + *  Copyright (C) 2008 Oren Laadan
> + *
> + *  This file is subject to the terms and conditions of the GNU General Public
> + *  License.  See the file COPYING in the main directory of the Linux
> + *  distribution for more details.
> + */
> +
> +#include <linux/mm_types.h>
> +
> +/*
> + * page-array chains: each cr_pgarr describes a set of <strcut page *,vaddr>
> + * tuples (where vaddr is the virtual address of a page in a particular mm).
> + * Specifically, we use separate arrays so that all vaddrs can be written
> + * and read at once.
> + */
> +
> +struct cr_pgarr {
> +       unsigned long *vaddrs;
> +       struct page **pages;
> +       unsigned int nr_used;
> +       struct list_head list;
> +};
> +
> +#define CR_PGARR_TOTAL  (PAGE_SIZE / sizeof(void *))
> +#define CR_PGARR_CHUNK  (4 * CR_PGARR_TOTAL)
> +
> +extern void cr_pgarr_free(struct cr_ctx *ctx);
> +extern struct cr_pgarr *cr_pgarr_current(struct cr_ctx *ctx);
> +extern void cr_pgarr_reset_all(struct cr_ctx *ctx);
> +
> +static inline int cr_pgarr_is_full(struct cr_pgarr *pgarr)
> +{
> +       return (pgarr->nr_used == CR_PGARR_TOTAL);
> +}
> +
> +#endif /* _CHECKPOINT_CKPT_MEM_H_ */
> diff --git a/checkpoint/ckpt_mem.c b/checkpoint/ckpt_mem.c
> new file mode 100644
> index 0000000..e0226f4
> --- /dev/null
> +++ b/checkpoint/ckpt_mem.c
> @@ -0,0 +1,492 @@
> +/*
> + *  Checkpoint memory contents
> + *
> + *  Copyright (C) 2008 Oren Laadan
> + *
> + *  This file is subject to the terms and conditions of the GNU General Public
> + *  License.  See the file COPYING in the main directory of the Linux
> + *  distribution for more details.
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/sched.h>
> +#include <linux/slab.h>
> +#include <linux/file.h>
> +#include <linux/pagemap.h>
> +#include <linux/mm_types.h>
> +#include <linux/checkpoint.h>
> +#include <linux/checkpoint_hdr.h>
> +
> +#include "checkpoint_arch.h"
> +#include "checkpoint_mem.h"
> +
> +/*
> + * utilities to alloc, free, and handle 'struct cr_pgarr' (page-arrays)
> + * (common to ckpt_mem.c and rstr_mem.c).
> + *
> + * The checkpoint context structure has two members for page-arrays:
> + *   ctx->pgarr_list: list head of the page-array chain
> + *
> + * During checkpoint (and restart) the chain tracks the dirty pages (page
> + * pointer and virtual address) of each MM. For a particular MM, these are
> + * always added to the head of the page-array chain (ctx->pgarr_list).
> + * This "current" page-array advances as necessary, and new page-array
> + * descriptors are allocated on-demand. Before the next chunk of pages,
> + * the chain is reset but not freed (that is, dereference page pointers).
> + */
> +
> +/* return first page-array in the chain */
> +static inline struct cr_pgarr *cr_pgarr_first(struct cr_ctx *ctx)
> +{
> +       if (list_empty(&ctx->pgarr_list))
> +               return NULL;
> +       return list_first_entry(&ctx->pgarr_list, struct cr_pgarr, list);
> +}
> +
> +/* release pages referenced by a page-array */
> +static void cr_pgarr_release_pages(struct cr_pgarr *pgarr)
> +{
> +       int i;
> +
> +       cr_debug("nr_used %d\n", pgarr->nr_used);
> +       /*
> +        * although both checkpoint and restart use 'nr_used', we only
> +        * collect pages during checkpoint; in restart we simply return
> +        */
> +       if (!pgarr->pages)
> +               return;
> +       for (i = pgarr->nr_used; i--; /**/)
> +               page_cache_release(pgarr->pages[i]);
> +}
> +
> +/* free a single page-array object */
> +static void cr_pgarr_free_one(struct cr_pgarr *pgarr)
> +{
> +       cr_pgarr_release_pages(pgarr);
> +       kfree(pgarr->pages);
> +       kfree(pgarr->vaddrs);
> +       kfree(pgarr);
> +}
> +
> +/* free a chain of page-arrays */
> +void cr_pgarr_free(struct cr_ctx *ctx)
> +{
> +       struct cr_pgarr *pgarr, *tmp;
> +
> +       list_for_each_entry_safe(pgarr, tmp, &ctx->pgarr_list, list) {
> +               list_del(&pgarr->list);
> +               cr_pgarr_free_one(pgarr);
> +       }
> +}
> +
> +/* allocate a single page-array object */
> +static struct cr_pgarr *cr_pgarr_alloc_one(unsigned long flags)
> +{
> +       struct cr_pgarr *pgarr;
> +
> +       pgarr = kzalloc(sizeof(*pgarr), GFP_KERNEL);
> +       if (!pgarr)
> +               return NULL;
> +
> +       pgarr->vaddrs = kmalloc(CR_PGARR_TOTAL * sizeof(unsigned long),
> +                              GFP_KERNEL);
> +       if (!pgarr->vaddrs)
> +               goto nomem;
> +
> +       /* pgarr->pages is needed only for checkpoint */
> +       if (flags & CR_CTX_CKPT) {
> +               pgarr->pages = kmalloc(CR_PGARR_TOTAL * sizeof(struct page *),
> +                                      GFP_KERNEL);
> +               if (!pgarr->pages)
> +                       goto nomem;
> +       }
> +
> +       return pgarr;
> +
> + nomem:
> +       cr_pgarr_free_one(pgarr);
> +       return NULL;
> +}
> +
> +/* cr_pgarr_current - return the next available page-array in the chain
> + * @ctx: checkpoint context
> + *
> + * Returns the first page-array in the list that has space. Extends the
> + * list if none has space.
> + */
> +struct cr_pgarr *cr_pgarr_current(struct cr_ctx *ctx)
> +{
> +       struct cr_pgarr *pgarr;
> +
> +       pgarr = cr_pgarr_first(ctx);
> +       if (pgarr && !cr_pgarr_is_full(pgarr))
> +               goto out;
> +       pgarr = cr_pgarr_alloc_one(ctx->flags);
> +       if (!pgarr)
> +               goto out;
> +       list_add(&pgarr->list, &ctx->pgarr_list);
> + out:
> +       return pgarr;
> +}
> +
> +/* reset the page-array chain (dropping page references if necessary) */
> +void cr_pgarr_reset_all(struct cr_ctx *ctx)
> +{
> +       struct cr_pgarr *pgarr;
> +
> +       list_for_each_entry(pgarr, &ctx->pgarr_list, list) {
> +               cr_pgarr_release_pages(pgarr);
> +               pgarr->nr_used = 0;
> +       }
> +}
> +
> +/*
> + * Checkpoint is outside the context of the checkpointee, so one cannot
> + * simply read pages from user-space. Instead, we scan the address space
> + * of the target to cherry-pick pages of interest. Selected pages are
> + * enlisted in a page-array chain (attached to the checkpoint context).
> + * To save their contents, each page is mapped to kernel memory and then
> + * dumped to the file descriptor.
> + */
> +
> +
> +/**
> + * cr_follow_page - return page pointer for pages that were modified
> + * @vma - target vma
> + * @addr - page address
> + *
> + * Looks up the page that correspond to the address in the vma, and
> + * returns the page if it was modified (and grabs a reference to it),
> + * or otherwise returns NULL (or error).
> + */
> +static struct page *
> +cr_follow_page(struct vm_area_struct *vma, unsigned long addr)
> +{
> +       struct page *page;
> +
> +       /*
> +        * simplified version of get_user_pages(): already have vma,
> +        * only need FOLL_ANON, and (for now) ignore fault stats.
> +        *
> +        * follow_page() will return NULL if the page is not present
> +        * (swapped), ZERO_PAGE(0) if the pte wasn't allocated, and
> +        * the actual page pointer otherwise.
> +        *
> +        * FIXME: consolidate with get_user_pages()
> +        */
> +
> +       cond_resched();
> +       while (!(page = follow_page(vma, addr, FOLL_ANON | FOLL_GET))) {
> +               int ret;
> +
> +               /* the page is swapped out - bring it in (optimize ?) */
> +               ret = handle_mm_fault(vma->vm_mm, vma, addr, 0);
> +               if (ret & VM_FAULT_ERROR) {
> +                       if (ret & VM_FAULT_OOM)
> +                               return ERR_PTR(-ENOMEM);
> +                       else if (ret & VM_FAULT_SIGBUS)
> +                               return ERR_PTR(-EFAULT);
> +                       else
> +                               BUG();
> +                       break;
> +               }
> +               cond_resched();
> +       }
> +
> +       if (IS_ERR(page))
> +               return page;
> +
> +       if (page == ZERO_PAGE(0)) {
> +               /* this is the zero page: ignore */
> +               page_cache_release(page);
> +               page = NULL;
> +       } else if (vma->vm_file && (page_mapping(page) != NULL)) {
> +               /* file backed clean cow: ignore */


If COW occur in file-backed pages, Is page_mapping is modified ?
I don't understand why this condition represent "file backed clean cow"?
Could you elaborate please?

quoted text
> +               page_cache_release(page);
> +               page = NULL;
> +       }
> +
> +       return page;
> +}
> +
> +/**
> + * cr_private_vma_fill_pgarr - fill a page-array with addr/page tuples
> + * @ctx - checkpoint context
> + * @pgarr - page-array to fill
> + * @vma - vma to scan
> + * @start - start address (updated)
> + *
> + * Returns the number of pages collected
> + */
> +static int
> +cr_private_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;
> +       int orig_used = pgarr->nr_used;
> +
> +       /* this function is only for private memory (anon or file-mapped) */
> +       BUG_ON(vma->vm_flags & (VM_SHARED | VM_MAYSHARE));
> +
> +       while (addr < end) {
> +               struct page *page;
> +
> +               page = cr_follow_page(vma, addr);
> +               if (IS_ERR(page))
> +                       return PTR_ERR(page);
> +
> +               if (page) {
> +                       pgarr->pages[pgarr->nr_used] = page;
> +                       pgarr->vaddrs[pgarr->nr_used] = addr;
> +                       pgarr->nr_used++;
> +               }
> +
> +               addr += PAGE_SIZE;
> +
> +               if (cr_pgarr_is_full(pgarr))
> +                       break;
> +       }
> +
> +       *start = addr;
> +       return pgarr->nr_used - orig_used;
> +}
> +
> +/* dump contents of a pages: use kmap_atomic() to avoid TLB flush */
> +static int cr_page_write(struct cr_ctx *ctx, struct page *page, char *buf)
> +{
> +       void *ptr;
> +
> +       ptr = kmap_atomic(page, KM_USER1);
> +       memcpy(buf, ptr, PAGE_SIZE);
> +       kunmap_atomic(page, KM_USER1);
> +
> +       return cr_kwrite(ctx, buf, PAGE_SIZE);
> +}
> +
> +/**
> + * cr_vma_dump_pages - dump pages listed in the ctx page-array chain
> + * @ctx - checkpoint context
> + * @total - total number of pages
> + *
> + * First dump all virtual addresses, followed by the contents of all pages
> + */
> +static int cr_vma_dump_pages(struct cr_ctx *ctx, int total)
> +{
> +       struct cr_pgarr *pgarr;
> +       char *buf;
> +       int i, ret = 0;
> +
> +       if (!total)
> +               return 0;
> +
> +       list_for_each_entry_reverse(pgarr, &ctx->pgarr_list, list) {
> +               ret = cr_kwrite(ctx, pgarr->vaddrs,
> +                               pgarr->nr_used * sizeof(*pgarr->vaddrs));
> +               if (ret < 0)
> +                       return ret;
> +       }
> +
> +       buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
> +       if (!buf)
> +               return -ENOMEM;
> +
> +       list_for_each_entry_reverse(pgarr, &ctx->pgarr_list, list) {
> +               for (i = 0; i < pgarr->nr_used; i++) {
> +                       ret = cr_page_write(ctx, pgarr->pages[i], buf);
> +                       if (ret < 0)
> +                               goto out;
> +               }
> +       }
> +
> + out:
> +       kfree(buf);
> +       return ret;
> +}
> +
> +/**
> + * cr_write_private_vma_contents - dump contents of a VMA with private memory
> + * @ctx - checkpoint context
> + * @vma - vma to scan
> + *
> + * Collect lists of pages that needs to be dumped, and corresponding
> + * virtual addresses into ctx->pgarr_list page-array chain. Then dump
> + * the addresses, followed by the page contents.
> + */
> +static int
> +cr_write_private_vma_contents(struct cr_ctx *ctx, struct vm_area_struct *vma)
> +{
> +       struct cr_hdr h;
> +       struct cr_hdr_pgarr *hh;
> +       unsigned long addr = vma->vm_start;
> +       struct cr_pgarr *pgarr;
> +       unsigned long cnt = 0;
> +       int ret;
> +
> +       /*
> +        * Work iteratively, collecting and dumping at most CR_PGARR_CHUNK
> +        * in each round. Each iterations is divided into two steps:
> +        *
> +        * (1) scan: scan through the PTEs of the vma to collect the pages
> +        * to dump (later we'll also make them COW), while keeping a list
> +        * of pages and their corresponding addresses on ctx->pgarr_list.
> +        *
> +        * (2) dump: write out a header specifying how many pages, followed
> +        * by the addresses of all pages in ctx->pgarr_list, followed by
> +        * the actual contents of all pages. (Then, release the references
> +        * to the pages and reset the page-array chain).
> +        *
> +        * (This split makes the logic simpler by first counting the pages
> +        * that need saving. More importantly, it allows for a future
> +        * optimization that will reduce application downtime by deferring
> +        * the actual write-out of the data to after the application is
> +        * allowed to resume execution).
> +        *
> +        * After dumpting the entire contents, conclude with a header that
> +        * specifies 0 pages to mark the end of the contents.
> +        */
> +
> +       h.type = CR_HDR_PGARR;
> +       h.len = sizeof(*hh);
> +       h.parent = 0;
> +
> +       while (addr < vma->vm_end) {
> +               pgarr = cr_pgarr_current(ctx);
> +               if (!pgarr)
> +                       return -ENOMEM;
> +               ret = cr_private_vma_fill_pgarr(ctx, pgarr, vma, &addr);
> +               if (ret < 0)
> +                       return ret;
> +               cnt += ret;
> +
> +               /* did we complete a chunk, or is this the last chunk ? */
> +               if (cnt >= CR_PGARR_CHUNK || (cnt && addr == vma->vm_end)) {
> +                       hh = cr_hbuf_get(ctx, sizeof(*hh));
> +                       hh->nr_pages = cnt;
> +                       ret = cr_write_obj(ctx, &h, hh);
> +                       cr_hbuf_put(ctx, sizeof(*hh));
> +                       if (ret < 0)
> +                               return ret;
> +
> +                       ret = cr_vma_dump_pages(ctx, cnt);
> +                       if (ret < 0)
> +                               return ret;
> +
> +                       cr_pgarr_reset_all(ctx);
> +               }
> +       }
> +
> +       /* mark end of contents with header saying "0" pages */
> +       hh = cr_hbuf_get(ctx, sizeof(*hh));
> +       hh->nr_pages = 0;
> +       ret = cr_write_obj(ctx, &h, hh);
> +       cr_hbuf_put(ctx, sizeof(*hh));
> +
> +       return ret;
> +}
> +
> +static int cr_write_vma(struct cr_ctx *ctx, struct vm_area_struct *vma)
> +{
> +       struct cr_hdr h;
> +       struct cr_hdr_vma *hh = cr_hbuf_get(ctx, sizeof(*hh));
> +       int vma_type, ret;
> +
> +       h.type = CR_HDR_VMA;
> +       h.len = sizeof(*hh);
> +       h.parent = 0;
> +
> +       hh->vm_start = vma->vm_start;
> +       hh->vm_end = vma->vm_end;
> +       hh->vm_page_prot = vma->vm_page_prot.pgprot;
> +       hh->vm_flags = vma->vm_flags;
> +       hh->vm_pgoff = vma->vm_pgoff;
> +
> +       if (vma->vm_flags & (VM_SHARED | VM_IO | VM_HUGETLB | VM_NONLINEAR)) {
> +               pr_warning("CR: unsupported VMA %#lx\n", vma->vm_flags);
> +               return -ETXTBSY;
> +       }
> +
> +       /* by default assume anon memory */
> +       vma_type = CR_VMA_ANON;
> +
> +       /*
> +        * if there is a backing file, assume private-mapped
> +        * (FIXME: check if the file is unlinked)
> +        */
> +       if (vma->vm_file)
> +               vma_type = CR_VMA_FILE;
> +
> +       hh->vma_type = vma_type;
> +
> +       ret = cr_write_obj(ctx, &h, hh);
> +       cr_hbuf_put(ctx, sizeof(*hh));
> +
> +       if (ret < 0)
> +               return ret;
> +
> +       /* save the file name, if relevant */
> +       if (vma->vm_file) {
> +               ret = cr_write_fname(ctx, &vma->vm_file->f_path, ctx->vfsroot);
> +               if (ret < 0)
> +                       return ret;
> +       }
> +
> +       ret = cr_write_private_vma_contents(ctx, vma);
> +
> +       return ret;
> +}
> +
> +int cr_write_mm(struct cr_ctx *ctx, struct task_struct *t)
> +{
> +       struct cr_hdr h;
> +       struct cr_hdr_mm *hh = cr_hbuf_get(ctx, sizeof(*hh));
> +       struct mm_struct *mm;
> +       struct vm_area_struct *vma;
> +       int objref, ret;
> +
> +       h.type = CR_HDR_MM;
> +       h.len = sizeof(*hh);
> +       h.parent = task_pid_vnr(t);
> +
> +       mm = get_task_mm(t);
> +
> +       objref = 0;     /* will be meaningful with multiple processes */
> +       hh->objref = objref;
> +
> +       down_read(&mm->mmap_sem);
> +
> +       hh->start_code = mm->start_code;
> +       hh->end_code = mm->end_code;
> +       hh->start_data = mm->start_data;
> +       hh->end_data = mm->end_data;
> +       hh->start_brk = mm->start_brk;
> +       hh->brk = mm->brk;
> +       hh->start_stack = mm->start_stack;
> +       hh->arg_start = mm->arg_start;
> +       hh->arg_end = mm->arg_end;
> +       hh->env_start = mm->env_start;
> +       hh->env_end = mm->env_end;
> +
> +       hh->map_count = mm->map_count;
> +
> +       /* FIX: need also mm->flags */
> +
> +       ret = cr_write_obj(ctx, &h, hh);
> +       cr_hbuf_put(ctx, sizeof(*hh));
> +       if (ret < 0)
> +               goto out;
> +
> +       /* write the vma's */
> +       for (vma = mm->mmap; vma; vma = vma->vm_next) {
> +               ret = cr_write_vma(ctx, vma);
> +               if (ret < 0)
> +                       goto out;
> +       }
> +
> +       ret = cr_write_mm_context(ctx, mm, objref);
> +
> + out:
> +       up_read(&mm->mmap_sem);
> +       mmput(mm);
> +       return ret;
> +}
> diff --git a/checkpoint/sys.c b/checkpoint/sys.c
> index 30863c6..c4ac157 100644
> --- a/checkpoint/sys.c
> +++ b/checkpoint/sys.c
> @@ -16,6 +16,8 @@
>  #include <linux/capability.h>
>  #include <linux/checkpoint.h>
>
> +#include "checkpoint_mem.h"
> +
>  /*
>  * helpers to write/read to/from the image file descriptor
>  *
> @@ -111,7 +113,6 @@ int cr_kread(struct cr_ctx *ctx, void *buf, int count)
>        return ret;
>  }
>
> -
>  /*
>  * helpers to manage CR contexts: allocated for each checkpoint and/or
>  * restart operation, and persists until the operation is completed.
> @@ -127,6 +128,11 @@ void cr_ctx_free(struct cr_ctx *ctx)
>
>        free_pages((unsigned long) ctx->hbuf, CR_HBUF_ORDER);
>
> +       if (ctx->vfsroot)
> +               path_put(ctx->vfsroot);
> +
> +       cr_pgarr_free(ctx);
> +
>        kfree(ctx);
>  }
>
> @@ -145,10 +151,17 @@ struct cr_ctx *cr_ctx_alloc(pid_t pid, int fd, unsigned long flags)
>        }
>
>        ctx->hbuf = (void *) __get_free_pages(GFP_KERNEL, CR_HBUF_ORDER);
> -       if (!ctx->hbuf) {
> -               cr_ctx_free(ctx);
> -               return ERR_PTR(-ENOMEM);
> -       }
> +       if (!ctx->hbuf)
> +               goto nomem;
> +
> +       /*
> +        * assume checkpointer is in container's root vfs
> +        * FIXME: this works for now, but will change with real containers
> +        */
> +       ctx->vfsroot = &current->fs->root;
> +       path_get(ctx->vfsroot);
> +
> +       INIT_LIST_HEAD(&ctx->pgarr_list);
>
>        ctx->pid = pid;
>        ctx->flags = flags;
> @@ -156,6 +169,10 @@ struct cr_ctx *cr_ctx_alloc(pid_t pid, int fd, unsigned long flags)
>        ctx->crid = atomic_inc_return(&cr_ctx_count);
>
>        return ctx;
> +
> + nomem:
> +       cr_ctx_free(ctx);
> +       return ERR_PTR(-ENOMEM);
>  }
>
>  /*
> diff --git a/include/asm-x86/checkpoint_hdr.h b/include/asm-x86/checkpoint_hdr.h
> index 44a903c..6bc61ac 100644
> --- a/include/asm-x86/checkpoint_hdr.h
> +++ b/include/asm-x86/checkpoint_hdr.h
> @@ -69,4 +69,9 @@ struct cr_hdr_cpu {
>
>  } __attribute__((aligned(8)));
>
> +struct cr_hdr_mm_context {
> +       __s16 ldt_entry_size;
> +       __s16 nldt;
> +} __attribute__((aligned(8)));
> +
>  #endif /* __ASM_X86_CKPT_HDR__H */
> diff --git a/include/linux/checkpoint.h b/include/linux/checkpoint.h
> index 5e53ae6..d74e64d 100644
> --- a/include/linux/checkpoint.h
> +++ b/include/linux/checkpoint.h
> @@ -10,6 +10,9 @@
>  *  distribution for more details.
>  */
>
> +#include <linux/path.h>
> +#include <linux/fs.h>
> +
>  #define CR_VERSION  1
>
>  struct cr_ctx {
> @@ -24,6 +27,10 @@ struct cr_ctx {
>
>        void *hbuf;             /* temporary buffer for headers */
>        int hpos;               /* position in headers buffer */
> +
> +       struct list_head pgarr_list;    /* page array to dump VMA contents */
> +
> +       struct path *vfsroot;   /* container root (FIXME) */
>  };
>
>  /* cr_ctx: flags */
> @@ -46,11 +53,16 @@ struct cr_hdr;
>
>  extern int cr_write_obj(struct cr_ctx *ctx, struct cr_hdr *h, void *buf);
>  extern int cr_write_string(struct cr_ctx *ctx, char *str, int len);
> +extern int cr_write_fname(struct cr_ctx *ctx,
> +                         struct path *path, struct path *root);
>
>  extern int cr_read_obj(struct cr_ctx *ctx, struct cr_hdr *h, void *buf, int n);
>  extern int cr_read_obj_type(struct cr_ctx *ctx, void *buf, int n, int type);
>  extern int cr_read_string(struct cr_ctx *ctx, void *str, int len);
>
> +extern int cr_write_mm(struct cr_ctx *ctx, struct task_struct *t);
> +extern int cr_read_mm(struct cr_ctx *ctx);
> +
>  extern int do_checkpoint(struct cr_ctx *ctx);
>  extern int do_restart(struct cr_ctx *ctx);
>
> diff --git a/include/linux/checkpoint_hdr.h b/include/linux/checkpoint_hdr.h
> index 03ec72e..2b110f1 100644
> --- a/include/linux/checkpoint_hdr.h
> +++ b/include/linux/checkpoint_hdr.h
> @@ -32,6 +32,7 @@ struct cr_hdr {
>  enum {
>        CR_HDR_HEAD = 1,
>        CR_HDR_STRING,
> +       CR_HDR_FNAME,
>
>        CR_HDR_TASK = 101,
>        CR_HDR_THREAD,
> @@ -39,6 +40,7 @@ enum {
>
>        CR_HDR_MM = 201,
>        CR_HDR_VMA,
> +       CR_HDR_PGARR,
>        CR_HDR_MM_CONTEXT,
>
>        CR_HDR_TAIL = 5001
> @@ -73,4 +75,34 @@ struct cr_hdr_task {
>        __s32 task_comm_len;
>  } __attribute__((aligned(8)));
>
> +struct cr_hdr_mm {
> +       __u32 objref;           /* identifier for shared objects */
> +       __u32 map_count;
> +
> +       __u64 start_code, end_code, start_data, end_data;
> +       __u64 start_brk, brk, start_stack;
> +       __u64 arg_start, arg_end, env_start, env_end;
> +} __attribute__((aligned(8)));
> +
> +/* vma subtypes */
> +enum vm_type {
> +       CR_VMA_ANON = 1,
> +       CR_VMA_FILE
> +};
> +
> +struct cr_hdr_vma {
> +       __u32 vma_type;
> +       __u32 _padding;
> +
> +       __u64 vm_start;
> +       __u64 vm_end;
> +       __u64 vm_page_prot;
> +       __u64 vm_flags;
> +       __u64 vm_pgoff;
> +} __attribute__((aligned(8)));
> +
> +struct cr_hdr_pgarr {
> +       __u64 nr_pages;         /* number of pages to saved */
> +} __attribute__((aligned(8)));
> +
>  #endif /* _CHECKPOINT_CKPT_HDR_H_ */
> --
> 1.5.4.3
>
> --
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-- 
Kinds regards,
MinChan Kim
--
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