Cc: Ingo
Cc: Juri
On 2015/1/28 11:53, Mike Galbraith wrote:
> On Wed, 2015-01-28 at 10:41 +0800, Zefan Li wrote:
>
>>> ---
>>> kernel/cpuset.c | 2 +-
>>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> --- a/kernel/cpuset.c
>>> +++ b/kernel/cpuset.c
>>> @@ -511,7 +511,7 @@ static int validate_change(struct cpuset
>>> * tasks.
>>> */
>>> ret = -EBUSY;
>>> - if (is_cpu_exclusive(cur) &&
>>> + if (is_cpu_exclusive(cur) && !cpumask_empty(cur->cpus_allowed) &&
>>> !cpuset_cpumask_can_shrink(cur->cpus_allowed,
>>> trial->cpus_allowed))
>>> goto out;
>>>
>>
>> We should instead fix cpuset_cpumask_can_shrink() to check if the return
>> value of
>> cpumask_any() >= nr_cpu_ids.
>
> I like 0 lines better, but ok.
>
> 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.
>
> [ 514.513841] CPU: 0 PID: 6942 Comm: shield.sh Not tainted 3.19.0-master #19
> [ 514.513841] Hardware name: MEDIONPC MS-7502/MS-7502, BIOS 6.00 PG
> 12/26/2007
> [ 514.513841] task: ffff880224552450 ti: ffff8800caab8000 task.ti:
> ffff8800caab8000
> [ 514.513841] RIP: 0010:[<ffffffff81073846>] [<ffffffff81073846>]
> cpuset_cpumask_can_shrink+0x56/0xb0
> [ 514.513841] RSP: 0018:ffff8800caabbda8 EFLAGS: 00010202
> [ 514.513841] RAX: 0000ffff00000000 RBX: ffff880037ae2ab8 RCX:
> 0000000000000000
> [ 514.513841] RDX: 0000000000012900 RSI: 0000000000000000 RDI:
> 000000000000000c
> [ 514.513841] RBP: ffff8800caabbdc8 R08: ffff880037ae2ab8 R09:
> 0000000000000034
> [ 514.513841] R10: 00000077e6fd3d1a R11: ffff88022e9b301c R12:
> ffff880223c98ab8
> [ 514.513841] R13: ffff880037ae2a00 R14: 0000000000000004 R15:
> ffff8802254b3c60
> [ 514.513841] FS: 00007fdbab533700(0000) GS:ffff88022fc00000(0000)
> knlGS:0000000000000000
> [ 514.513841] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [ 514.513841] CR2: 00007ffff8ab8000 CR3: 00000000bef11000 CR4:
> 00000000000007f0
> [ 514.513841] Stack:
> [ 514.513841] ffff880223c98ab8 ffffffff81a46c20 ffff880223c98a00
> ffff880037ae2a00
> [ 514.513841] ffff8800caabbdf8 ffffffff810cb82a ffff8800caabbdf8
> ffff880037ae2a00
> [ 514.513841] ffff8800ca9e5240 0000000000000000 ffff8800caabbe48
> ffffffff810cc877
> [ 514.513841] Call Trace:
> [ 514.513841] [<ffffffff810cb82a>] validate_change+0x18a/0x200
> [ 514.513841] [<ffffffff810cc877>] cpuset_write_resmask+0x3b7/0x720
> [ 514.513841] [<ffffffff810c4d58>] cgroup_file_write+0x38/0x100
> [ 514.513841] [<ffffffff811d953a>] kernfs_fop_write+0x12a/0x180
> [ 514.513841] [<ffffffff8116e1a3>] vfs_write+0xb3/0x1d0
> [ 514.513841] [<ffffffff8116ed06>] SyS_write+0x46/0xb0
> [ 514.513841] [<ffffffff8159ced6>] system_call_fastpath+0x16/0x1b
>
> Signed-off-by: Mike Galbraith <umgwanakikb...@gmail.com>
>
Acked-by: Zefan Li <lize...@huawei.com>
This fixes f82f80426f7afcf55953924e71555984a4bd6ce6
("sched/deadline: Ensure that updates to exclusive cpusets don't break AC").
> ---
> kernel/sched/core.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> --- a/kernel/sched/core.c
> +++ b/kernel/sched/core.c
> @@ -4739,6 +4739,9 @@ int cpuset_cpumask_can_shrink(const stru
> 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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