From b8ec2e49bb3b1403569a0db599338ba5edcac09a Mon Sep 17 00:00:00 2001
From: Bui Quang Minh <minhquangbui99@gmail.com>
Date: Wed, 15 Dec 2021 22:53:09 +0700
Subject: [PATCH 125/245] ipc: Add support for checkpoint/restore hugetlb
 System V shared memory

Attach the System V shared memory segments to the address space via shmat() to
determine if they are backed by hugetlb and their page size. Use these
information for setting the correct flags on restore.

Signed-off-by: Bui Quang Minh <minhquangbui99@gmail.com>
---
 criu/ipc_ns.c        | 48 ++++++++++++++++++++++++++++++++++++++++++--
 images/ipc-shm.proto |  1 +
 2 files changed, 47 insertions(+), 2 deletions(-)

diff --git a/criu/ipc_ns.c b/criu/ipc_ns.c
index a2eb72f28..4fe082fbb 100644
--- a/criu/ipc_ns.c
+++ b/criu/ipc_ns.c
@@ -15,6 +15,7 @@
 #include "sysctl.h"
 #include "ipc_ns.h"
 #include "shmem.h"
+#include "types.h"
 
 #include "protobuf.h"
 #include "images/ipc-var.pb-c.h"
@@ -354,6 +355,42 @@ static int dump_ipc_shm_pages(const IpcShmEntry *shm)
 	return ret;
 }
 
+static int dump_shm_hugetlb_flag(IpcShmEntry *shm, int id, unsigned long size)
+{
+	void *addr;
+	int ret, hugetlb_flag, exit_code = -1;
+	struct stat st;
+	char path[64];
+
+	addr = shmat(id, NULL, SHM_RDONLY);
+	if (addr == (void *)-1) {
+		pr_perror("Failed to attach shm");
+		return -1;
+	}
+
+	/* The shm segment size may not be aligned,
+	 * we need to align it up to next page size
+	 */
+	size = (size + PAGE_SIZE - 1) & ~(PAGE_SIZE - 1);
+	snprintf(path, sizeof(path), "/proc/self/map_files/%lx-%lx", (unsigned long)addr, (unsigned long)addr + size);
+
+	ret = stat(path, &st);
+	if (ret < 0) {
+		pr_perror("Can't stat map_files");
+		goto detach;
+	}
+
+	if (is_hugetlb_dev(st.st_dev, &hugetlb_flag)) {
+		shm->has_hugetlb_flag = true;
+		shm->hugetlb_flag = hugetlb_flag | SHM_HUGETLB;
+	}
+
+	exit_code = 0;
+detach:
+	shmdt(addr);
+	return exit_code;
+}
+
 static int dump_ipc_shm_seg(struct cr_img *img, int id, const struct shmid_ds *ds)
 {
 	IpcShmEntry shm = IPC_SHM_ENTRY__INIT;
@@ -364,6 +401,10 @@ static int dump_ipc_shm_seg(struct cr_img *img, int id, const struct shmid_ds *d
 	shm.size = ds->shm_segsz;
 	shm.has_in_pagemaps = true;
 	shm.in_pagemaps = true;
+
+	if (dump_shm_hugetlb_flag(&shm, id, ds->shm_segsz))
+		return -1;
+
 	fill_ipc_desc(id, shm.desc, &ds->shm_perm);
 	pr_info_ipc_shm(&shm);
 
@@ -798,7 +839,7 @@ static int prepare_ipc_shm_pages(struct cr_img *img, const IpcShmEntry *shm)
 
 static int prepare_ipc_shm_seg(struct cr_img *img, const IpcShmEntry *shm)
 {
-	int ret, id;
+	int ret, id, hugetlb_flag = 0;
 	struct sysctl_req req[] = {
 		{ "kernel/shm_next_id", &shm->desc->id, CTL_U32 },
 	};
@@ -813,7 +854,10 @@ static int prepare_ipc_shm_seg(struct cr_img *img, const IpcShmEntry *shm)
 		return ret;
 	}
 
-	id = shmget(shm->desc->key, shm->size, shm->desc->mode | IPC_CREAT | IPC_EXCL);
+	if (shm->has_hugetlb_flag)
+		hugetlb_flag = shm->hugetlb_flag;
+
+	id = shmget(shm->desc->key, shm->size, hugetlb_flag | shm->desc->mode | IPC_CREAT | IPC_EXCL);
 	if (id == -1) {
 		pr_perror("Failed to create shm set");
 		return -errno;
diff --git a/images/ipc-shm.proto b/images/ipc-shm.proto
index 7865dad8d..c5feebac0 100644
--- a/images/ipc-shm.proto
+++ b/images/ipc-shm.proto
@@ -8,4 +8,5 @@ message ipc_shm_entry {
 	required ipc_desc_entry		desc	= 1;
 	required uint64			size	= 2;
 	optional bool			in_pagemaps = 3;
+	optional uint32			hugetlb_flag = 4;
 }
-- 
2.35.1