Commit-ID: bb2bc55a694d45cdeda91b6f28ab2adec28125ef
Gitweb: http://git.kernel.org/tip/bb2bc55a694d45cdeda91b6f28ab2adec28125ef
Author: Mike Galbraith <umgwanakikbuti@xxxxxxxxx>
AuthorDate: Wed, 28 Jan 2015 04:53:55 +0100
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Wed, 28 Jan 2015 15:28:15 +0100
sched: Fix crash if cpuset_cpumask_can_shrink() is passed an empty cpumask
While creating an exclusive cpuset, we passed cpuset_cpumask_can_shrink()
an empty cpumask (cur), and dl_bw_of(cpumask_any(cur)) made boom with it:
CPU: 0 PID: 6942 Comm: shield.sh Not tainted 3.19.0-master #19
Hardware name: MEDIONPC MS-7502/MS-7502, BIOS 6.00 PG 12/26/2007
task: ffff880224552450 ti: ffff8800caab8000 task.ti: ffff8800caab8000
RIP: 0010:[<ffffffff81073846>] [<ffffffff81073846>] cpuset_cpumask_can_shrink+0x56/0xb0
[...]
Call Trace:
[<ffffffff810cb82a>] validate_change+0x18a/0x200
[<ffffffff810cc877>] cpuset_write_resmask+0x3b7/0x720
[<ffffffff810c4d58>] cgroup_file_write+0x38/0x100
[<ffffffff811d953a>] kernfs_fop_write+0x12a/0x180
[<ffffffff8116e1a3>] vfs_write+0xb3/0x1d0
[<ffffffff8116ed06>] SyS_write+0x46/0xb0
[<ffffffff8159ced6>] system_call_fastpath+0x16/0x1b
Signed-off-by: Mike Galbraith <umgwanakikbuti@xxxxxxxxx>
Acked-by: Zefan Li <lizefan@xxxxxxxxxx>
Fixes: f82f80426f7a ("sched/deadline: Ensure that updates to exclusive cpusets don't break AC")
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Link: http://lkml.kernel.org/r/1422417235.5716.5.camel@xxxxxxxxxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
kernel/sched/core.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index c0accc0..5c86687 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -4642,6 +4642,9 @@ int cpuset_cpumask_can_shrink(const struct cpumask *cur,
struct dl_bw *cur_dl_b;
unsigned long flags;
+ if (!cpumask_weight(cur))
+ return ret;
+
rcu_read_lock_sched();
cur_dl_b = dl_bw_of(cpumask_any(cur));
trial_cpus = cpumask_weight(trial);
--
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