Messages in this thread Patch in this message | | | Date | Thu, 21 Jul 2011 18:30:11 GMT | From | tip-bot for Bianca Lutz <> | Subject | [tip:sched/core] sched: Do not attempt to destroy uninitialized rt_bandwidth |
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Commit-ID: 99bc52429f11d1f4f81495ac8237085aaeb6bccf Gitweb: http://git.kernel.org/tip/99bc52429f11d1f4f81495ac8237085aaeb6bccf Author: Bianca Lutz <sowilo@cs.tu-berlin.de> AuthorDate: Wed, 13 Jul 2011 20:13:36 +0200 Committer: Ingo Molnar <mingo@elte.hu> CommitDate: Thu, 21 Jul 2011 18:01:51 +0200
sched: Do not attempt to destroy uninitialized rt_bandwidth
If a task group is to be created and alloc_fair_sched_group() fails, then the rt_bandwidth of the corresponding task group is not yet initialized. The caller, sched_create_group(), starts a clean up procedure which calls free_rt_sched_group() which unconditionally destroys the not yet initialized rt_bandwidth.
This crashes or hangs the system in lock_hrtimer_base(): UP systems dereference a NULL pointer, while SMP systems loop endlessly on a condition that cannot become true.
This patch simply avoids the destruction of rt_bandwidth when the initialization code path was not reached.
(This was discovered by accident with a custom kernel modification.)
Signed-off-by: Bianca Lutz <sowilo@cs.tu-berlin.de> Signed-off-by: Jan Schoenherr <schnhrr@cs.tu-berlin.de> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/1310580816-10861-7-git-send-email-schnhrr@cs.tu-berlin.de Signed-off-by: Ingo Molnar <mingo@elte.hu> --- kernel/sched.c | 3 ++- 1 files changed, 2 insertions(+), 1 deletions(-)
diff --git a/kernel/sched.c b/kernel/sched.c index 3b3826e..f107204 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -8383,7 +8383,8 @@ static void free_rt_sched_group(struct task_group *tg) { int i; - destroy_rt_bandwidth(&tg->rt_bandwidth); + if (tg->rt_se) + destroy_rt_bandwidth(&tg->rt_bandwidth); for_each_possible_cpu(i) { if (tg->rt_rq)
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