[BUG] Why does mwait_idle_with_hints() call MWAIT with interruptsdisabled ?

[Tomar]

Hi,
   I'm seeing following crash consistently on my Dell R310 machine. The server
is mostly idling while it crashes.

I see that mwait_idle_with_hints() does not enable local interrupts before
calling MWAIT. That does not appear right, as the only way now that this
processor can be brought out of the sleep is by some other processor setting
the need_resched flag that it is waiting on. In very low load situations this
can take long and NMI lockup detection can kick in.

mwait_idle() correctly reenables interrupts before the MWAIT call. Why is
mwait_idle_with_hints() different, apart from the extra sleep state hints.

I'v checked the latest kernel sources and this part remains the same.

This code is pretty old, so I wonder if other people are also seeing this
problem.

Thanks,
Tomar


Following is the crash backtrace.


[ 4997.164914] BUG: NMI Watchdog detected LOCKUP on CPU1, ip
ffffffff8101a399, registers:
[ 4997.165025] CPU 1
[ 4997.165121] Modules linked in: netconsole configfs xfrm_user
xfrm4_tunnel tunnel4 ipcomp xfrm_ipcomp esp4 ah4 deflate zlib_deflate
ctr twofish twofish_common camellia serpent blowfish cast5 des_generic
cryptd aes_x86_64 aes_generic xcbc rmd160 sha256_generic sha1_generic
crypto_null af_key bonding xfs exportfs joydev usbhid hid igb dca
e1000e sctp crc32c libcrc32c dell_wmi 8021q dcdbas garp stp
power_meter tcp_westwood tcp_veno tcp_vegas tcp_hybla bnx2 lp parport
[ 4997.167856] Pid: 0, comm: swapper Not tainted 2.6.32-27-server-test
#0test2 PowerEdge R310
[ 4997.167968] RIP: 0010:[<ffffffff8101a399>]  [<ffffffff8101a399>]
mwait_idle_with_hints+0x99/0xf0
[ 4997.168109] RSP: 0018:ffff88013baffe48  EFLAGS: 00000046
[ 4997.168217] RAX: 0000000000000020 RBX: 0000000000000020 RCX: 0000000000000001
[ 4997.168290] RDX: 0000000000000000 RSI: ffff88013bafffd8 RDI: 0000000000000000
[ 4997.168363] RBP: ffff88013baffe68 R08: 0000000000000000 R09: 0000000000000060
[ 4997.168435] R10: 0000048d19b9c2bd R11: 0000000000000000 R12: 0000000000000001
[ 4997.168508] R13: 0000000000000003 R14: 0000000000000000 R15: 0000000000000000
[ 4997.168581] FS:  0000000000000000(0000) GS:ffff88000d620000(0000)
knlGS:0000000000000000
[ 4997.168724] CS:  0010 DS: 0018 ES: 0018 CR0: 000000008005003b
[ 4997.168795] CR2: 00007f03388da000 CR3: 0000000001001000 CR4: 00000000000006e0
[ 4997.168867] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[ 4997.168940] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
[ 4997.169013] Process swapper (pid: 0, threadinfo ffff88013bafe000,
task ffff88013baf44a0)
[ 4997.169153] Stack:
[ 4997.169216]  ffff880139e09530 ffff880139e09000 122be5d25988d251
0000000000000000
[ 4997.169427] <0> ffff88013baffe78 ffffffff8102c9c2 ffff88013baffe88
ffffffff8130e6e6
[ 4997.169741] <0> ffff88013baffee8 ffffffff8130ea04 ffff88013baffea8
ffffffff81088718
[ 4997.170115] Call Trace:
[ 4997.170182]  [<ffffffff8102c9c2>] acpi_processor_ffh_cstate_enter+0x32/0x40
[ 4997.170310]  [<ffffffff8130e6e6>] acpi_idle_do_entry+0x15/0x67
[ 4997.170382]  [<ffffffff8130ea04>] acpi_idle_enter_bm+0x20b/0x2c8
[ 4997.170456]  [<ffffffff81088718>] ? hrtimer_start+0x18/0x20
[ 4997.170529]  [<ffffffff81551f96>] ? notifier_call_chain+0x16/0x80
[ 4997.170602]  [<ffffffff814437dd>] ? menu_select+0x10d/0x2a0
[ 4997.170673]  [<ffffffff81442717>] cpuidle_idle_call+0xa7/0x140
[ 4997.170746]  [<ffffffff81010e63>] cpu_idle+0xb3/0x110
[ 4997.170817]  [<ffffffff81547086>] start_secondary+0xa8/0xaa
[ 4997.170887] Code: 8b 34 25 c8 cb 00 00 48 89 d1 48 8d 86 38 e0 ff
ff 0f 01 c8 0f ae f0 48 8b 86 38 e0 ff ff a8 08 75 09 48 89 d8 4c 89
e1 0f 01 c9 <48> 8b 1c 24 4c 8b 64 24 08 4c 8b 6c 24 10 4c 8b 74 24 18
c9 c3
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