Issue

Server becomes unresponsive sporadically under heavy CPU load. This is largely due to system time on the CPUs. An error similar to below may be observed just prior to the hang in messages:

lockd_up: makesock failed, error=-98

During the hang the console may display mount.nfs soft lockup warnings with stack traces similar to the following:

BUG: soft lockup - CPU#3 stuck for 67s! [mount.nfs:17929]
Pid: 17929, comm: mount.nfs Tainted: G           --L------------    2.6.32-642.1.1.el6.x86_64 #1 VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform
RIP: 0010:[<ffffffff810ad305>]  [<ffffffff810ad305>] blocking_notifier_chain_register+0x45/0xa0
RSP: 0018:ffff88001057fc28  EFLAGS: 00000246
RAX: ffffffffa03ef940 RBX: ffff88001057fc38 RCX: 0000000000000000
RDX: ffffffffa03ef948 RSI: ffffffffa03ef940 RDI: ffffffff81b30300
RBP: ffffffff8100bc0e R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: ffffffffa03aaa32 R15: ffffffffa03aaa1a
FS:  00007ff811d54700(0000) GS:ffff880002380000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
CR2: 00007fb918277000 CR3: 000000007896e000 CR4: 00000000000407e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Process mount.nfs (pid: 17929, threadinfo ffff88001057c000, task ffff88007be16040)
Stack:
 ffff880036453000 ffff88001057fca8 ffff88001057fc48 ffffffff814e5628
<d> ffff88001057fc78 ffffffffa03e5f79 0000000000000202 0000000000000001
<d> ffff88001057fca8 ffff88007d631480 ffff88001057fc98 ffffffffa03e365d
Call Trace:
 [<ffffffff814e5628>] ? register_inetaddr_notifier+0x18/0x20
 [<ffffffffa03e5f79>] ? lockd_up+0x99/0x220 [lockd]
 [<ffffffffa03e365d>] ? nlmclnt_init+0x1d/0x70 [lockd]
 [<ffffffffa046f897>] ? nfs_start_lockd+0x97/0xd0 [nfs]
 [<ffffffffa0471b46>] ? nfs_create_server+0x166/0x590 [nfs]
 [<ffffffffa047f13c>] ? nfs_get_sb+0x2dc/0x880 [nfs]
 [<ffffffff8119c8ab>] ? vfs_kern_mount+0x7b/0x1b0
 [<ffffffff8119ca52>] ? do_kern_mount+0x52/0x130
 [<ffffffff811be9ab>] ? do_mount+0x2fb/0x930
 [<ffffffff811bf070>] ? sys_mount+0x90/0xe0
 [<ffffffff8100b0d2>] ? system_call_fastpath+0x16/0x1b