From: Mike Galbraith Date: Sun, 28 Oct 2012 19:19:23 +0000 (-0700) Subject: sched/autogroup: Fix crash on reboot when autogroup is disabled X-Git-Tag: omap-for-v3.8/fixes-for-merge-window-v4-signed~75^2~2^2~4^2 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=5258f386ea4e8454bc801fb443e8a4217da1947c;p=pandora-kernel.git sched/autogroup: Fix crash on reboot when autogroup is disabled Due to these two commits: 8323f26ce342 sched: Fix race in task_group() 800d4d30c8f2 sched, autogroup: Stop going ahead if autogroup is disabled ... autogroup scheduling's dynamic knobs are wrecked. With both patches applied, all you have to do to crash a box is disable autogroup during boot up, then reboot.. boom, NULL pointer dereference due to 800d4d30 not allowing autogroup to move things, and 8323f26ce making that the only way to switch runqueues. Remove most of the (dysfunctional) knobs and turn the remaining sched_autogroup_enabled knob readonly. If the user fiddles with cgroups hereafter, once tasks are moved, autogroup won't mess with them again unless they call setsid(). No knobs, no glitz, nada, just a cute little thing folks can turn on if they don't want to muck about with cgroups and/or systemd. Signed-off-by: Mike Galbraith Cc: Xiaotian Feng Cc: Peter Zijlstra Cc: Xiaotian Feng Cc: Linus Torvalds Cc: Andrew Morton Cc: Oleg Nesterov Cc: # v3.6 Link: http://lkml.kernel.org/r/1351451963.4999.8.camel@maggy.simpson.net Signed-off-by: Ingo Molnar --- Reading git-diff-tree failed