zdtm: simulate lazy migration with page server that can send pages

Lazy migration requires both dumped and restored processes to coexist at
the same time. This breaks some basic assumptions in the zdtm design.
Simulation of lazy migration with the page server allows testing most of
the involved code paths without major intervention into zdtm
infrastructure.

travis-ci: success for lazy-pages: improve testability (rev2)
Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>

test/zdtm.py

@@ -775,7 +775,9 @@ class criu:
 		self.__iter = 0
 		self.__prev_dump_iter = None
 		self.__page_server = (opts['page_server'] and True or False)
-		self.__lazy_pages = (opts['lazy_pages'] and True or False)
+		self.__remote_lazy_pages = (opts['remote_lazy_pages'] and True or False)
+		self.__lazy_pages = (self.__remote_lazy_pages or
+				     opts['lazy_pages'] and True or False)
 		self.__restore_sibling = (opts['sibling'] and True or False)
 		self.__join_ns = (opts['join_ns'] and True or False)
 		self.__empty_ns = (opts['empty_ns'] and True or False)
@@ -963,7 +965,13 @@ class criu:
 			r_opts.append('mnt[zdtm]:%s' % criu_dir)
 
 		if self.__lazy_pages:
-			self.__criu_act("lazy-pages", opts = ["--daemon", "--pidfile", "lp.pid"])
+			lp_opts = ["--daemon", "--pidfile", "lp.pid"]
+			if self.__remote_lazy_pages:
+				lp_opts += ['--page-server', "--port", "12345"]
+				ps_opts = ["--daemon", "--pidfile", "ps.pid",
+					   "--port", "12345", "--lazy-pages"]
+				self.__criu_act("page-server", opts = ps_opts)
+			self.__criu_act("lazy-pages", opts = lp_opts)
 			r_opts += ["--lazy-pages"]
 
 		if self.__leave_stopped:
@@ -1435,7 +1443,7 @@ class launcher:
 
 		nd = ('nocr', 'norst', 'pre', 'iters', 'page_server', 'sibling', 'stop', 'empty_ns',
 				'fault', 'keep_img', 'report', 'snaps', 'sat', 'script', 'rpc', 'lazy_pages',
-				'join_ns', 'dedup', 'sbs', 'freezecg', 'user', 'dry_run', 'noauto_dedup')
+				'join_ns', 'dedup', 'sbs', 'freezecg', 'user', 'dry_run', 'noauto_dedup', 'remote_lazy_pages')
 		arg = repr((name, desc, flavor, {d: self.__opts[d] for d in nd}))
 
 		if self.__use_log:
@@ -1697,7 +1705,7 @@ def run_tests(opts):
 					l.skip(t, "samens test in the same namespace")
 					continue
 
-			if opts['lazy_pages']:
+			if opts['lazy_pages'] or opts['remote_lazy_pages']:
 				if test_flag(tdesc, 'nolazy'):
 					l.skip(t, "lazy pages are not supported")
 					continue
@@ -1937,6 +1945,7 @@ rp.add_argument("--report", help = "Generate summary report in directory")
 rp.add_argument("--keep-going", help = "Keep running tests in spite of failures", action = 'store_true')
 rp.add_argument("--ignore-taint", help = "Don't care about a non-zero kernel taint flag", action = 'store_true')
 rp.add_argument("--lazy-pages", help = "restore pages on demand", action = 'store_true')
+rp.add_argument("--remote-lazy-pages", help = "simulate lazy migration", action = 'store_true')
 
 lp = sp.add_parser("list", help = "List tests")
 lp.set_defaults(action = list_tests)