df -Th 命令卡死

[root@node1 ~]# yum -y install strace

[root@node1 ~]# strace df -h
execve("/usr/bin/df", ["df", "-h"], [/* 23 vars */]) = 0
brk(0)                                  = 0xbcd000
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7fb5411fc000
access("/etc/ld.so.preload", R_OK)      = -1 ENOENT (No such file or directory)
open("/etc/ld.so.cache", O_RDONLY|O_CLOEXEC) = 3
fstat(3, {st_mode=S_IFREG|0644, st_size=21124, ...}) = 0
mmap(NULL, 21124, PROT_READ, MAP_PRIVATE, 3, 0) = 0x7fb5411f6000
close(3)                                = 0
open("/usr/lib64/libc.so.6", O_RDONLY|O_CLOEXEC) = 3
read(3, "\177ELF\2\1\1\3\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0@\34\2\0\0\0\0\0"..., 832) = 832
fstat(3, {st_mode=S_IFREG|0755, st_size=2118128, ...}) = 0
mmap(NULL, 3932672, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7fb540c1d000
mprotect(0x7fb540dd3000, 2097152, PROT_NONE) = 0
mmap(0x7fb540fd3000, 24576, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x1b6000) = 0x7fb540fd3000
mmap(0x7fb540fd9000, 16896, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x7fb540fd9000
close(3)                                = 0
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7fb5411f5000
mmap(NULL, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7fb5411f3000
arch_prctl(ARCH_SET_FS, 0x7fb5411f3740) = 0
mprotect(0x7fb540fd3000, 16384, PROT_READ) = 0
mprotect(0x616000, 4096, PROT_READ)     = 0
mprotect(0x7fb5411fd000, 4096, PROT_READ) = 0
munmap(0x7fb5411f6000, 21124)           = 0
brk(0)                                  = 0xbcd000
brk(0xbee000)                           = 0xbee000
brk(0)                                  = 0xbee000
open("/usr/lib/locale/locale-archive", O_RDONLY|O_CLOEXEC) = 3
fstat(3, {st_mode=S_IFREG|0644, st_size=106070960, ...}) = 0
mmap(NULL, 106070960, PROT_READ, MAP_PRIVATE, 3, 0) = 0x7fb53a6f4000
close(3)                                = 0
open("/usr/share/locale/locale.alias", O_RDONLY|O_CLOEXEC) = 3
fstat(3, {st_mode=S_IFREG|0644, st_size=2502, ...}) = 0
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7fb5411fb000
read(3, "# Locale name alias data base.\n#"..., 4096) = 2502
read(3, "", 4096)                       = 0
close(3)                                = 0
munmap(0x7fb5411fb000, 4096)            = 0
open("/usr/share/locale/en_US.UTF-8/LC_MESSAGES/coreutils.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/share/locale/en_US.utf8/LC_MESSAGES/coreutils.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/share/locale/en_US/LC_MESSAGES/coreutils.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/share/locale/en.UTF-8/LC_MESSAGES/coreutils.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/share/locale/en.utf8/LC_MESSAGES/coreutils.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/share/locale/en/LC_MESSAGES/coreutils.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/etc/mtab", O_RDONLY|O_CLOEXEC)   = 3
fstat(3, {st_mode=S_IFREG|0444, st_size=0, ...}) = 0
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7fb5411fb000
read(3, "rootfs / rootfs rw 0 0\nsysfs /sy"..., 1024) = 1024
read(3, "w,nosuid,nodev,noexec,relatime,m"..., 1024) = 1024
read(3, "uid,nodev,relatime,size=1626796k"..., 1024) = 96
read(3, "", 1024)                       = 0
close(3)                                = 0
munmap(0x7fb5411fb000, 4096)            = 0
stat("/", {st_mode=S_IFDIR|0555, st_size=269, ...}) = 0
stat("/sys", {st_mode=S_IFDIR|0555, st_size=0, ...}) = 0
stat("/proc", {st_mode=S_IFDIR|0555, st_size=0, ...}) = 0
stat("/dev", {st_mode=S_IFDIR|0755, st_size=2880, ...}) = 0
stat("/sys/kernel/security", {st_mode=S_IFDIR|0755, st_size=0, ...}) = 0
stat("/dev/shm", {st_mode=S_IFDIR|S_ISVTX|0777, st_size=40, ...}) = 0
stat("/dev/pts", {st_mode=S_IFDIR|0755, st_size=0, ...}) = 0
stat("/run", {st_mode=S_IFDIR|0755, st_size=780, ...}) = 0
stat("/sys/fs/cgroup", {st_mode=S_IFDIR|0755, st_size=340, ...}) = 0
stat("/sys/fs/cgroup/systemd", {st_mode=S_IFDIR|0755, st_size=0, ...}) = 0
stat("/sys/fs/pstore", {st_mode=S_IFDIR|0755, st_size=0, ...}) = 0
stat("/sys/fs/cgroup/freezer", {st_mode=S_IFDIR|0755, st_size=0, ...}) = 0
stat("/sys/fs/cgroup/net_cls,net_prio", {st_mode=S_IFDIR|0755, st_size=0, ...}) = 0
stat("/sys/fs/cgroup/devices", {st_mode=S_IFDIR|0755, st_size=0, ...}) = 0
stat("/sys/fs/cgroup/memory", {st_mode=S_IFDIR|0755, st_size=0, ...}) = 0
stat("/sys/fs/cgroup/cpu,cpuacct", {st_mode=S_IFDIR|0755, st_size=0, ...}) = 0
stat("/sys/fs/cgroup/perf_event", {st_mode=S_IFDIR|0755, st_size=0, ...}) = 0
stat("/sys/fs/cgroup/blkio", {st_mode=S_IFDIR|0755, st_size=0, ...}) = 0
stat("/sys/fs/cgroup/pids", {st_mode=S_IFDIR|0755, st_size=0, ...}) = 0
stat("/sys/fs/cgroup/hugetlb", {st_mode=S_IFDIR|0755, st_size=0, ...}) = 0
stat("/sys/fs/cgroup/cpuset", {st_mode=S_IFDIR|0755, st_size=0, ...}) = 0
stat("/sys/kernel/config", {st_mode=S_IFDIR|0755, st_size=0, ...}) = 0
stat("/", {st_mode=S_IFDIR|0555, st_size=269, ...}) = 0
stat("/var/lib/nfs/rpc_pipefs", {st_mode=S_IFDIR|0555, st_size=0, ...}) = 0
stat("/proc/sys/fs/binfmt_misc",

1. systemctl restart proc-sys-fs-binfmt_misc.automount;
2. 升级到最新 systemd-219-57 版本;
3. 按照红帽知识库的步骤对 proc-sys-fs-binfmt_misc.automount 进行 mask 操作, 只进行静态的 mount 操作

我用的第一种方式，亲测好使。

df 卡住问题在本质上还是由于 systemd 和 kernel 之间存在竞争而引起的, 导致其它程序访问挂载点的时候出现 hang 住的现象。
根据redhat bugzilla的描述, 只要解决掉 mount 和 automount 过程中可能产生的竞争即可, 关闭proc-sys-fs-binfmt_misc.automount释放已经存在的竞争来解决 df hang 住的问题