Re: [PATCH] mm/mempolicy: fix potential mpol_new leak in shared_policy_replace

[Miaohe Lin <linmiaohe@huawei.com>]

On 2022/3/21 16:59, Michal Hocko wrote:
> On Sat 19-03-22 18:42:33, Miaohe Lin wrote:
> [...]
>> This would be triggered easily with below code snippet in my virtual machine:
>>
>> 	shmid = shmget((key_t)5566, 1024 * PAGE_SIZE, 0666|IPC_CREAT);
>> 	shm = shmat(shmid, 0, 0);
>> 	loop {
>> 		mbind(shm, 1024 * PAGE_SIZE, MPOL_LOCAL, mask, maxnode, 0);
>> 		mbind(shm + 128 * PAGE_SIZE, 128 * PAGE_SIZE, MPOL_DEFAULT, mask, maxnode, 0);
>> 	}
>>
>> If there're many process doing the above work, mpol_new will be leaked easily.
>> So should I resend this patch with Cc stable? But it seems I'am not supposed
>> to make this decision and the maintainer will take care of this?
> 
> I would just add
> Fixes: 42288fe366c4 ("mm: mempolicy: Convert shared_policy mutex to spinlock")
> Cc: stable # 3.8
> 
> And also add your above reproducer snippet added to the original changelog.
> This would be more then enough to conclude the importance.

Will do. Many thanks for your patience and suggestion!

> 
> Thank you for working hard on this!

Thanks. :)

>