[CRIU] [PATCH v3 4/8] memory: don't use parent memdump if detected possible pid reuse
Pavel Tikhomirov
ptikhomirov at virtuozzo.com
Wed Feb 14 14:28:59 MSK 2018
From: ptikhomirov <ptikhomirov at virtuozzo.com>
We have a problem when a pid is reused between consequent dumps we can't
understand if pagemap and pages from images of parent dump are invalid
to restore these pid already. That can lead even to wrong memory
restored for these pid, see the test in last patch.
So these is a try do separate processes with (likely) invalid previous
memory dump from processes with 100% valid previous dump.
For that we use the value of /proc/<pid>/stat's start_time and also the
timestamp of each (pre)dump. If the start time is strictly less than the
timestamp, that means that the pagemap for these pid from previous dump
is valid - was done for exactly the same process.
Creation time is in centiseconds by default so if predump is really fast
(<1csec) we can have false negative decisions for some processes, but in
case of long running processes we are fine.
https://jira.sw.ru/browse/PSBM-67502
v2: remove __maybe_unused for get_parent_stats; fix get_parent_stats to
have static typing; print warning only if unsure; check has_dump_uptime
v3: read parent stats from image only once; reuse stat from previous
parse_pid_stat call on dump
Signed-off-by: Pavel Tikhomirov <ptikhomirov at virtuozzo.com>
---
criu/cr-dump.c | 4 ++--
criu/include/mem.h | 5 ++++-
criu/mem.c | 56 ++++++++++++++++++++++++++++++++++++++++++++++++++----
criu/stats.c | 2 +-
4 files changed, 59 insertions(+), 8 deletions(-)
diff --git a/criu/cr-dump.c b/criu/cr-dump.c
index 9e8425504..d0cf922b7 100644
--- a/criu/cr-dump.c
+++ b/criu/cr-dump.c
@@ -1290,7 +1290,7 @@ static int pre_dump_one_task(struct pstree_item *item)
mdc.pre_dump = true;
mdc.lazy = false;
- ret = parasite_dump_pages_seized(item, &vmas, &mdc, parasite_ctl);
+ ret = parasite_dump_pages_seized(item, &vmas, &mdc, parasite_ctl, NULL);
if (ret)
goto err_cure;
@@ -1449,7 +1449,7 @@ static int dump_one_task(struct pstree_item *item)
mdc.pre_dump = false;
mdc.lazy = opts.lazy_pages;
- ret = parasite_dump_pages_seized(item, &vmas, &mdc, parasite_ctl);
+ ret = parasite_dump_pages_seized(item, &vmas, &mdc, parasite_ctl, &pps_buf);
if (ret)
goto err_cure;
diff --git a/criu/include/mem.h b/criu/include/mem.h
index bb897c599..aab8e183f 100644
--- a/criu/include/mem.h
+++ b/criu/include/mem.h
@@ -4,6 +4,8 @@
#include <stdbool.h>
#include "int.h"
#include "vma.pb-c.h"
+#include "pid.h"
+#include "proc_parse.h"
struct parasite_ctl;
struct vm_area_list;
@@ -26,7 +28,8 @@ extern unsigned long dump_pages_args_size(struct vm_area_list *vmas);
extern int parasite_dump_pages_seized(struct pstree_item *item,
struct vm_area_list *vma_area_list,
struct mem_dump_ctl *mdc,
- struct parasite_ctl *ctl);
+ struct parasite_ctl *ctl,
+ struct proc_pid_stat* stat);
#define PME_PRESENT (1ULL << 63)
#define PME_SWAP (1ULL << 62)
diff --git a/criu/mem.c b/criu/mem.c
index 4c6942a11..a1646fd7d 100644
--- a/criu/mem.c
+++ b/criu/mem.c
@@ -30,9 +30,11 @@
#include "fault-injection.h"
#include "prctl.h"
#include <compel/compel.h>
+#include "proc_parse.h"
#include "protobuf.h"
#include "images/pagemap.pb-c.h"
+#include "images/stats.pb-c.h"
static int task_reset_dirty_track(int pid)
{
@@ -294,7 +296,8 @@ static int __parasite_dump_pages_seized(struct pstree_item *item,
struct parasite_dump_pages_args *args,
struct vm_area_list *vma_area_list,
struct mem_dump_ctl *mdc,
- struct parasite_ctl *ctl)
+ struct parasite_ctl *ctl,
+ struct proc_pid_stat *stat)
{
pmc_t pmc = PMC_INIT;
struct page_pipe *pp;
@@ -303,6 +306,7 @@ static int __parasite_dump_pages_seized(struct pstree_item *item,
int ret = -1;
unsigned cpp_flags = 0;
unsigned long pmc_size;
+ bool possible_pid_reuse = false;
if (opts.check_only)
return 0;
@@ -360,6 +364,49 @@ static int __parasite_dump_pages_seized(struct pstree_item *item,
xfer.parent = NULL + 1;
}
+ if (xfer.parent) {
+ struct proc_pid_stat pps_buf;
+ static StatsEntry *stats;
+ unsigned long dump_ticks;
+ unsigned long clock_ticks;
+
+ clock_ticks = sysconf(_SC_CLK_TCK);
+ if (clock_ticks == -1) {
+ pr_perror("Failed to get clock ticks via sysconf");
+ goto out_xfer;
+ }
+
+ if (stat) {
+ pps_buf = *stat;
+ } else {
+ ret = parse_pid_stat(item->pid->real, &pps_buf);
+ if (ret < 0)
+ goto out_xfer;
+ }
+
+ if (!stats) {
+ stats = get_parent_stats();
+ if (!stats)
+ goto out_xfer;
+ }
+
+ if (stats->dump->has_dump_uptime) {
+ dump_ticks = stats->dump->dump_uptime/(USEC_PER_SEC / clock_ticks);
+
+ if (pps_buf.start_time >= dump_ticks) {
+ /* Print warning when we are not sure */
+ if (pps_buf.start_time == dump_ticks)
+ pr_warn("Will do full redump for pid=%d due " \
+ "to possible pid reuse\n",
+ item->pid->real);
+ possible_pid_reuse = true;
+ }
+ } else
+ pr_warn_once("Parent image has no dump timestamp, " \
+ "pid reuse detection OFF!\n");
+ }
+
+
/*
* Step 1 -- generate the pagemap
*/
@@ -386,7 +433,7 @@ static int __parasite_dump_pages_seized(struct pstree_item *item,
else {
again:
ret = generate_iovs(vma_area, pp, map, &off,
- has_parent);
+ has_parent && !possible_pid_reuse);
if (ret == -EAGAIN) {
BUG_ON(!(pp->flags & PP_CHUNK_MODE));
@@ -436,7 +483,8 @@ static int __parasite_dump_pages_seized(struct pstree_item *item,
int parasite_dump_pages_seized(struct pstree_item *item,
struct vm_area_list *vma_area_list,
struct mem_dump_ctl *mdc,
- struct parasite_ctl *ctl)
+ struct parasite_ctl *ctl,
+ struct proc_pid_stat* stat)
{
int ret;
struct parasite_dump_pages_args *pargs;
@@ -463,7 +511,7 @@ int parasite_dump_pages_seized(struct pstree_item *item,
return -1;
}
- ret = __parasite_dump_pages_seized(item, pargs, vma_area_list, mdc, ctl);
+ ret = __parasite_dump_pages_seized(item, pargs, vma_area_list, mdc, ctl, stat);
if (ret) {
pr_err("Can't dump page with parasite\n");
/* Parasite will unprotect VMAs after fail in fini() */
diff --git a/criu/stats.c b/criu/stats.c
index 4823e48de..4d646c104 100644
--- a/criu/stats.c
+++ b/criu/stats.c
@@ -213,7 +213,7 @@ void write_stats(int what)
display_stats(what, &stats);
}
-__maybe_unused StatsEntry *get_parent_stats(void)
+StatsEntry *get_parent_stats(void)
{
struct cr_img *img;
StatsEntry *se;
--
2.14.3
More information about the CRIU
mailing list