linux-kernel - [PATCH 0/3] patches for stop

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]

Message-ID: <481678F5.7080504@jp.fujitsu.com>
Date:	Tue, 29 Apr 2008 10:25:09 +0900
From:	Hidetoshi Seto <seto.hidetoshi@...fujitsu.com>
To:	Rusty Russell <rusty@...tcorp.com.au>, linux-kernel@...r.kernel.org
Subject: [PATCH 0/3] patches for stop_machine

Hi Rusty and all,

This is a proposal of minor improvement for kernel/stop_machine.c

[PATCH 1/3] stop_machine: short exit path for if we cannot create enough threads
[PATCH 2/3] stop_machine: add timeout for child thread deployment
[PATCH 3/3] stop_machine: add stopmachine_timeout sysctl entry

The main topic is "how about adding timeout for stop_machine?"
I think it will act as a safety net.

For example (of silly situation), system can hung with following way:

  # ./silly.sh
  run an evil loop task on AP
   pid 6138's current affinity mask: ff
   pid 6138's new affinity mask: fe
   to pretend lock up, chrt -f -p 99 6138
   loop[6138] is on CPU #4
  to do stopmachine, try to off #7
  echo 0 > /sys/devices/system/cpu/cpu7/online
  (never return)

After applying patch set here, it can be prevented.

  # ./silly.sh
   :
  echo 0 > /sys/devices/system/cpu/cpu7/online
  stopmachine: Failed to stop machine in time(5s). Are there any CPUs on file?
  ./silly.sh: line 22: echo: write error: Device or resource busy
  offline is failed
  OK, kill evil loop[6138]
  try to off #7 again
  echo 0 > /sys/devices/system/cpu/cpu7/online
  CPU #7 is now offline
  done!

Please refer description of each patch for the detail.
All comments are welcomed.

Thanks,
H.Seto
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/