[CRIU] [PATCH RFC 8/8] criu: lazy-pages: enable remoting of lazy pages

[Mike Rapoport]

The remote lazy pages variant can be run as follows:

src# criu dump -t <pid> --lazy-pages --port 9876 -D /tmp/1 &
src# while ! sudo fuser 9876/tcp ; do sleep 1; done
src# scp -r /tmp/1/ dst:/tmp/

dst# criu lazy-pages --lazy-addr /tmp/uffd.sock --page-server \
                     --address dst --port 9876 -D /tmp/1 &
dst# criu restore --lazy-pages --lazy-addr /tmp/uffd.sock -D /tmp/1

Signed-off-by: Mike Rapoport <rppt at linux.vnet.ibm.com>
---
 criu/cr-dump.c   | 54 ++++++++++++++++++++++++++++++++++++++++++++++++++++--
 criu/page-read.c |  2 +-
 criu/uffd.c      |  9 ++++++++-
 3 files changed, 61 insertions(+), 4 deletions(-)

diff --git a/criu/cr-dump.c b/criu/cr-dump.c
index 1a551b4..faca73b 100644
--- a/criu/cr-dump.c
+++ b/criu/cr-dump.c
@@ -1298,7 +1298,7 @@ static int dump_one_task(struct pstree_item *item)
 		}
 	}
 
-	ret = parasite_dump_pages_seized(parasite_ctl, &vmas, false);
+	ret = parasite_dump_pages_seized(parasite_ctl, &vmas, opts.lazy_pages);
 	if (ret)
 		goto err_cure;
 
@@ -1338,7 +1338,10 @@ static int dump_one_task(struct pstree_item *item)
 		goto err;
 	}
 
-	ret = parasite_cure_seized(parasite_ctl);
+	if (opts.lazy_pages)
+		ret = parasite_cure_remote(parasite_ctl);
+	else
+		ret = parasite_cure_seized(parasite_ctl);
 	if (ret) {
 		pr_err("Can't cure (pid: %d) from parasite\n", pid);
 		goto err;
@@ -1525,6 +1528,49 @@ err:
 	return cr_pre_dump_finish(ret);
 }
 
+static int cr_lazy_mem_dump(void)
+{
+	struct pstree_item *item;
+	int ret = 0;
+
+	pr_info("Lazy pages: pre-dumping memory\n");
+	for_each_pstree_item(item) {
+		struct parasite_ctl *ctl = item->parasite_ctl;
+		struct page_xfer xfer;
+
+		timing_start(TIME_MEMWRITE);
+		ret = open_page_xfer(&xfer, CR_FD_PAGEMAP, ctl->pid.virt);
+		if (ret < 0)
+			goto err;
+
+		ret = page_xfer_dump_pages(&xfer, ctl->mem_pp, 0, false);
+
+		xfer.close(&xfer);
+
+		if (ret)
+			goto err;
+
+		timing_stop(TIME_MEMWRITE);
+	}
+
+	pr_info("Starting lazy pages server\n");
+	ret = cr_page_server(false, -1);
+
+	for_each_pstree_item(item) {
+		struct parasite_ctl *ctl = item->parasite_ctl;
+		destroy_page_pipe(ctl->mem_pp);
+		parasite_cure_local(ctl);
+	}
+
+err:
+	if (ret)
+		pr_err("Lazy pages transfer FAILED.\n");
+	else
+		pr_info("Lazy pages transfer finished successfully\n");
+
+	return ret;
+}
+
 static int cr_dump_finish(int ret)
 {
 	int post_dump_ret = 0;
@@ -1583,6 +1629,10 @@ static int cr_dump_finish(int ret)
 		network_unlock();
 		delete_link_remaps();
 	}
+
+	if (opts.lazy_pages)
+		ret = cr_lazy_mem_dump();
+
 	pstree_switch_state(root_item,
 			    (ret || post_dump_ret) ?
 			    TASK_ALIVE : opts.final_state);
diff --git a/criu/page-read.c b/criu/page-read.c
index e5ec76a..203b170 100644
--- a/criu/page-read.c
+++ b/criu/page-read.c
@@ -92,7 +92,7 @@ static void skip_pagemap_pages(struct page_read *pr, unsigned long len)
 		return;
 
 	pr_debug("\tpr%u Skip %lu bytes from page-dump\n", pr->id, len);
-	if (!pr->pe->in_parent)
+	if (!pr->pe->in_parent && !opts.lazy_pages)
 		lseek(img_raw_fd(pr->pi), len, SEEK_CUR);
 	pr->cvaddr += len;
 }
diff --git a/criu/uffd.c b/criu/uffd.c
index ef1ff89..d140d38 100644
--- a/criu/uffd.c
+++ b/criu/uffd.c
@@ -33,6 +33,7 @@
 #include "xmalloc.h"
 #include "syscall-codes.h"
 #include "restorer.h"
+#include "page-xfer.h"
 
 #undef  LOG_PREFIX
 #define LOG_PREFIX "lazy-pages: "
@@ -363,7 +364,10 @@ static int uffd_copy_page(struct lazy_pages_info *lpi, __u64 address,
 	struct uffdio_copy uffdio_copy;
 	int rc;
 
-	rc = get_page(lpi, address, dest);
+	if (opts.use_page_server)
+		rc = get_remote_pages(lpi->pid, address, 1, dest);
+	else
+		rc = get_page(lpi, address, dest);
 	if (rc <= 0)
 		return rc;
 
@@ -861,6 +865,9 @@ int cr_lazy_pages()
 	if (prepare_uffds(epollfd))
 		return -1;
 
+	if (connect_to_page_server())
+		return -1;
+
 	ret = handle_requests(epollfd, events);
 	lpi_hash_fini();
 
-- 
1.9.1