[CRIU] [PATCH 07/12] restore: map taks_args and thread_args earlier

[Andrey Wagin]

2012/12/18 Pavel Emelyanov <xemul at parallels.com>:
> On 12/18/2012 10:36 AM, Andrey Vagin wrote:
>> A task_args saves a number of shared pending signals and
>> thread_args save a number of private pendign signals.
>>
>> All signal images should be read for determing a size of siginfo-s.
>
> And how does mapping a part of the restorer area help?

numbers of siginfo-s are saved in these structures.

>
>> Signed-off-by: Andrey Vagin <avagin at openvz.org>
>> ---
>>  cr-restore.c | 20 ++++++++++++++++----
>>  1 file changed, 16 insertions(+), 4 deletions(-)
>>
>> diff --git a/cr-restore.c b/cr-restore.c
>> index cb4d943..1b39f97 100644
>> --- a/cr-restore.c
>> +++ b/cr-restore.c
>> @@ -1630,6 +1630,20 @@ static int sigreturn_restore(pid_t pid, CoreEntry *core)
>>                       current->nr_threads,
>>                       KBYTES(restore_thread_vma_len));
>>
>> +     /* VMA we need to run task_restore code */
>> +     mem = mmap(NULL,
>> +                     restore_task_vma_len + restore_thread_vma_len,
>> +                     PROT_READ | PROT_WRITE,
>> +                     MAP_PRIVATE | MAP_ANON, 0, 0);
>> +     if (mem == MAP_FAILED) {
>> +             pr_err("Can't mmap section for restore code\n");
>> +             goto err;
>> +     }
>> +
>> +     memzero(mem, restore_task_vma_len + restore_thread_vma_len);
>> +     task_args       = mem;
>> +     thread_args     = mem + restore_task_vma_len;
>> +
>>       restore_bootstrap_len = restorer_len +
>>                               restore_task_vma_len +
>>                               restore_thread_vma_len +
>> @@ -1673,16 +1687,14 @@ static int sigreturn_restore(pid_t pid, CoreEntry *core)
>>       exec_mem_hint += restorer_len;
>>
>>       /* VMA we need to run task_restore code */
>> -     mem = mmap((void *)exec_mem_hint,
>> +     mem = mremap(mem, restore_task_vma_len + restore_thread_vma_len,
>>                       restore_task_vma_len + restore_thread_vma_len,
>> -                     PROT_READ | PROT_WRITE,
>> -                     MAP_PRIVATE | MAP_ANON | MAP_FIXED, 0, 0);
>> +                     MREMAP_FIXED | MREMAP_MAYMOVE, (void *)exec_mem_hint);
>>       if (mem != (void *)exec_mem_hint) {
>>               pr_err("Can't mmap section for restore code\n");
>>               goto err;
>>       }
>>
>> -     memzero(mem, restore_task_vma_len + restore_thread_vma_len);
>>       task_args       = mem;
>>       thread_args     = mem + restore_task_vma_len;
>>
>>
>
>