fix(host): check min_free_kbytes size is enough (#23287)

pkg/hostman/hostinfo/hostinfo.go

@@ -626,11 +626,10 @@ func (h *SHostInfo) tuneSystem() {
 	if minMemMb < 100 {
 		minMemMb = 100
 	}
-	minMemKB := fmt.Sprintf("%d", 2*minMemMb*1024)
+	minMemKB := 2 * minMemMb * 1024
 	kv := map[string]string{
 		"/proc/sys/vm/swappiness":                        "0",
 		"/proc/sys/vm/vfs_cache_pressure":                "350",
-		"/proc/sys/vm/min_free_kbytes":                   minMemKB,
 		"/proc/sys/net/ipv4/tcp_mtu_probing":             "2",
 		"/proc/sys/net/ipv4/neigh/default/gc_thresh1":    "1024",
 		"/proc/sys/net/ipv4/neigh/default/gc_thresh2":    "4096",
@@ -640,6 +639,13 @@ func (h *SHostInfo) tuneSystem() {
 
 		"/proc/sys/net/netfilter/nf_conntrack_tcp_be_liberal": "1",
 	}
+	ret, err := fileutils2.FileGetIntContent("/proc/sys/vm/min_free_kbytes")
+	if err != nil {
+		log.Errorf("failed get /proc/sys/vm/min_free_kbytes: %s", err)
+	} else if ret < minMemKB {
+		kv["/proc/sys/vm/min_free_kbytes"] = fmt.Sprintf("%d", minMemKB)
+	}
+
 	for k, v := range kv {
 		sysutils.SetSysConfig(k, v)
 	}

pkg/util/fileutils2/fileutils.go

@@ -22,6 +22,7 @@ import (
 	"path"
 	"path/filepath"
 	"regexp"
+	"strconv"
 	"strings"
 
 	"yunion.io/x/log"
@@ -219,6 +220,18 @@ func FileGetContents(file string) (string, error) {
 	return string(content), nil
 }
 
+func FileGetIntContent(file string) (int, error) {
+	content, err := FileGetContents(file)
+	if err != nil {
+		return -1, errors.Wrap(err, "FileGetContents")
+	}
+	val, err := strconv.Atoi(strings.TrimSpace(content))
+	if err != nil {
+		return -1, errors.Wrapf(err, "convert %s to int", content)
+	}
+	return val, nil
+}
+
 func GetFsFormat(diskPath string) string {
 	ret, err := procutils.NewCommand("blkid", "-o", "value", "-s", "TYPE", diskPath).Output()
 	if err != nil {