[CRIU] [PATCHv0 5/8] shmem: implement dirty page tracking for anon shared memory

[Pavel Emelyanov]

On 12/06/2015 04:15 PM, Eugene Batalov wrote:
> From: Fyodor <bocharovfedor at gmail.com>
> 
> To track anon shared vma pages dirtiness we create a bitmap for it.
> Each bit in this bitmap corresponds to particular page in vma. Bit with
> value of 1 in this map states that page is dirty. Bit 0 states that the
> page is clean.
> 
> Signed-off-by: Fyodor Bocharov <fbocharov at yandex.ru>
> Signed-off-by: Eugene Batalov <eabatalov89 at gmail.com>
> ---
>  cr-dump.c       | 18 ++++++++++++++----
>  include/shmem.h |  3 ++-
>  shmem.c         | 47 ++++++++++++++++++++++++++++++++++++++++++++---
>  3 files changed, 60 insertions(+), 8 deletions(-)
> 
> diff --git a/cr-dump.c b/cr-dump.c
> index 466880e..e96c3a3 100644
> --- a/cr-dump.c
> +++ b/cr-dump.c
> @@ -82,6 +82,7 @@
>  #include "seccomp.h"
>  #include "seize.h"
>  #include "fault-injection.h"
> +#include "pagemap-cache.h"
>  
>  #include "asm/dump.h"
>  
> @@ -407,6 +408,7 @@ static int dump_task_mm(pid_t pid, const struct proc_pid_stat *stat,
>  	MmEntry mme = MM_ENTRY__INIT;
>  	struct vma_area *vma_area;
>  	int ret = -1, i = 0;
> +	pmc_t pmc = PMC_INIT;
>  
>  	pr_info("\n");
>  	pr_info("Dumping mm (pid: %d)\n", pid);
> @@ -415,10 +417,15 @@ static int dump_task_mm(pid_t pid, const struct proc_pid_stat *stat,
>  	mme.n_vmas = vma_area_list->nr;
>  	mme.vmas = xmalloc(mme.n_vmas * sizeof(VmaEntry *));
>  	if (!mme.vmas)
> -		goto err;
> +		goto init_err;
> +
> +	if (pmc_init(&pmc, pid, &vma_area_list->h,
> +			 vma_area_list->longest * PAGE_SIZE))
> +		goto init_err;

This 2nd pmc walk is not cool. Can we pick up dirty bits for shared areas in
__parasite_dump_pages_seized()? There's already a loop over vma-s and the
pmc is already set up, so adding another "if (vma is anon shared)" into the
list_for_each_entry(vma_area, &vma_area_list->h, list) loop should work.

>  
>  	list_for_each_entry(vma_area, &vma_area_list->h, list) {
>  		VmaEntry *vma = vma_area->e;
> +		u64 *map;
>  
>  		pr_info_vma(vma_area);
>