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| author | Dinakar Guniguntala <dino@in.ibm.com> | 2009-10-22 18:08:00 +0530 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2009-10-29 09:08:26 +0100 |
| commit | 465a3c40221645220ddd83a612d3d695ff4a2468 (patch) | |
| tree | d36c34b97bf02bd6bd98d7d313608e1584e8caf9 /kernel | |
| parent | 1e2ea8a1c5fbcfea1ea85cf2c33475f08ed2c46c (diff) | |
| download | lwn-465a3c40221645220ddd83a612d3d695ff4a2468.tar.gz lwn-465a3c40221645220ddd83a612d3d695ff4a2468.zip | |
sched: Fix dynamic power-balancing crash
This crash:
[ 1774.088275] divide error: 0000 [#1] SMP
[ 1774.100355] CPU 13
[ 1774.102498] Modules linked in:
[ 1774.105631] Pid: 30881, comm: hackbench Not tainted 2.6.31-rc8-tip-01308-g484d664-dirty #1629 X8DTN
[ 1774.114807] RIP: 0010:[<ffffffff81041c38>] [<ffffffff81041c38>]
sched_balance_self+0x19b/0x2d4
Triggers because update_group_power() modifies the sd tree and does
temporary calculations there - not considering that other CPUs
could observe intermediate values, such as the zero initial value.
Calculate it in a temporary variable instead. (we need no memory
barrier as these are all statistical values anyway)
Got the same oops with the backport to -rt
Signed-off-by: Dinakar Guniguntala <dino@in.ibm.com>
Cc: John Stultz <johnstul@us.ibm.com>
Cc: Darren Hart <dvhltc@us.ibm.com>
Cc: John Kacur <jkacur@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/sched.c | 7 |
1 files changed, 5 insertions, 2 deletions
diff --git a/kernel/sched.c b/kernel/sched.c index 2b346fbd10ae..c78dcfed504b 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -3864,19 +3864,22 @@ static void update_group_power(struct sched_domain *sd, int cpu) { struct sched_domain *child = sd->child; struct sched_group *group, *sdg = sd->groups; + unsigned long power; if (!child) { update_cpu_power(sd, cpu); return; } - sdg->cpu_power = 0; + power = 0; group = child->groups; do { - sdg->cpu_power += group->cpu_power; + power += group->cpu_power; group = group->next; } while (group != child->groups); + + sdg->cpu_power = power; } /** |