linux-kernel - [regression] 3.7+ suspend to RAM/offline CPU fails with nmi

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Date:	Wed, 21 Nov 2012 10:01:33 +0100
From:	Norbert Warmuth <nwarmuth@...nline.de>
To:	linux-kernel@...r.kernel.org
Cc:	Thomas Gleixner <tglx@...utronix.de>
Subject: [regression] 3.7+ suspend to RAM/offline CPU fails with nmi_watchdog=0 (bisected)

3.7-rc6 booted with nmi_watchdog=0 fails to suspend to RAM or
offline CPUs. It's reproducable with a KVM guest and physical
system. 

git bisect identified (config used for bisecting attached):
  commit bcd951cf10f24e341defcd002c15a1f4eea13ddb
  Author: Thomas Gleixner <tglx@...utronix.de>
  Date:   Mon Jul 16 10:42:38 2012 +0000
  
      watchdog: Use hotplug thread infrastructure

(re-)tested with:
- uname -m: x86_64
- getconf _NPROCESSORS_ONLN: 8
- kernel: 3.7-rc6
- cpuid (physical system): "Intel(R) Core(TM) i7-2630QM CPU @ 2.00GHz"

Tests:
  echo processors > /sys/power/pm_test
  echo mem > /sys/power/state

Results:
- nmi_watchdog=1: OK

- nmi_watchdog=1, echo 0 > /proc/sys/kernel/nmi_watchdog: OK

- nmi_watchdog=0: FAIL
  Disabling non-boot CPUs ...
  Unregister pv shared memory for cpu 1
  [hang, reset required]

- nmi_watchdog=0, echo 0 > /sys/devices/system/cpu/cpu7/online: FAIL
  Unregister pv shared memory for cpu 7
  [hang, reset required]

- nmi_watchdog=0, bcd951cf10f reverted: OK

I've used to require nmi_watchdog=0 for virtualization but have not
verified it lately and a quick search finds references related to 
oprofile and power saving.

Norbert


View attachment "bisect-config" of type "text/plain" (35168 bytes)