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Handling iov generation for non-PROT_READ regions

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Skip iov-generation for regions not having
PROT_READ, since process_vm_readv syscall
can't process them during "read" pre-dump.
Handle random order of "read" & "splice"
pre-dumps.

Signed-off-by: Abhishek Dubey <dubeyabhishek777@gmail.com>
Signed-off-by: Andrei Vagin <avagin@gmail.com>
This commit is contained in:
Abhishek Dubey 2019-10-03 19:39:19 +05:30 committed by Andrei Vagin
parent 20d4920a8b
commit e0ea21ad5e
3 changed files with 60 additions and 2 deletions
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5
criu/cr-dump.c
View File

@ -1485,6 +1485,9 @@ static int cr_pre_dump_finish(int status)
if (ret)
goto err;
he.has_pre_dump_mode = true;
he.pre_dump_mode = opts.pre_dump_mode;
pstree_switch_state(root_item, TASK_ALIVE);
timing_stop(TIME_FROZEN);
@ -1914,6 +1917,8 @@ int cr_dump_tasks(pid_t pid)
if (ret)
goto err;
he.has_pre_dump_mode = false;
ret = write_img_inventory(&he);
if (ret)
goto err;

56
criu/mem.c
View File

@ -351,7 +351,8 @@ static int generate_vma_iovs(struct pstree_item *item, struct vma_area *vma,
struct page_pipe *pp, struct page_xfer *xfer,
struct parasite_dump_pages_args *args,
struct parasite_ctl *ctl, pmc_t *pmc,
bool has_parent, bool pre_dump)
bool has_parent, bool pre_dump,
int parent_predump_mode)
{
u64 off = 0;
u64 *map;
@ -361,6 +362,52 @@ static int generate_vma_iovs(struct pstree_item *item, struct vma_area *vma,
!vma_area_is(vma, VMA_ANON_SHARED))
return 0;
/*
* To facilitate any combination of pre-dump modes to run after
* one another, we need to take extra care as discussed below.
*
* The SPLICE mode pre-dump, processes all type of memory regions,
* whereas READ mode pre-dump skips processing those memory regions
* which lacks PROT_READ flag.
*
* Now on mixing pre-dump modes:
* If SPLICE mode follows SPLICE mode : no issue
* -> everything dumped both the times
*
* If READ mode follows READ mode : no issue
* -> non-PROT_READ skipped both the time
*
* If READ mode follows SPLICE mode : no issue
* -> everything dumped at first,
* the non-PROT_READ skipped later
*
* If SPLICE mode follows READ mode : Need special care
*
* If READ pre-dump happens first, then it has skipped processing
* non-PROT_READ regions. Following SPLICE pre-dump expects pagemap
* entries for all mappings in parent pagemap, but last READ mode
* pre-dump cycle has skipped processing & pagemap generation for
* non-PROT_READ regions. So SPLICE mode throws error of missing
* pagemap entry for encountered non-PROT_READ mapping.
*
* To resolve this, the pre-dump-mode is stored in current pre-dump's
* inventoy file. This pre-dump mode is read back from this file
* (present in parent pre-dump dir) as parent-pre-dump-mode during
* next pre-dump.
*
* If parent-pre-dump-mode and next-pre-dump-mode are in READ-mode ->
* SPLICE-mode order, then SPLICE mode doesn't expect mappings for
* non-PROT_READ regions in parent-image and marks "has_parent=false".
*/
if (!(vma->e->prot & PROT_READ)) {
if (opts.pre_dump_mode == PRE_DUMP_READ && pre_dump)
return 0;
if ((parent_predump_mode == PRE_DUMP_READ &&
opts.pre_dump_mode == PRE_DUMP_SPLICE) || !pre_dump)
has_parent = false;
}
if (vma_entry_is(vma->e, VMA_AREA_AIORING)) {
if (pre_dump)
return 0;
@ -406,6 +453,7 @@ static int __parasite_dump_pages_seized(struct pstree_item *item,
unsigned long pmc_size;
int possible_pid_reuse = 0;
bool has_parent;
int parent_predump_mode = -1;
pr_info("\n");
pr_info("Dumping pages (type: %d pid: %d)\n", CR_FD_PAGES, item->pid->real);
@ -472,9 +520,13 @@ static int __parasite_dump_pages_seized(struct pstree_item *item,
*/
args->off = 0;
has_parent = !!xfer.parent && !possible_pid_reuse;
if(mdc->parent_ie)
parent_predump_mode = mdc->parent_ie->pre_dump_mode;
list_for_each_entry(vma_area, &vma_area_list->h, list) {
ret = generate_vma_iovs(item, vma_area, pp, &xfer, args, ctl,
&pmc, has_parent, mdc->pre_dump);
&pmc, has_parent, mdc->pre_dump,
parent_predump_mode);
if (ret < 0)
goto out_xfer;
}

1
images/inventory.proto
View File

@ -16,4 +16,5 @@ message inventory_entry {
optional uint32 root_cg_set = 5;
optional lsmtype lsmtype = 6;
optional uint64 dump_uptime = 8;
optional uint32 pre_dump_mode = 9;
}