Re: [PATCH RESEND] mm/hugetlb: Don't call region_abort if region_chg fails

[Mike Kravetz]

On 03/30/2017 05:28 AM, Dmitry Vyukov wrote:
> On Wed, Mar 29, 2017 at 11:17 PM, Andrew Morton
> <akpm@xxxxxxxxxxxxxxxxxxxx> wrote:
>> On Wed, 29 Mar 2017 14:08:02 -0700 Mike Kravetz <mike.kravetz@xxxxxxxxxx> wrote:
>>
>>>
>>> syzkaller fuzzer found this bug, that resulted in the following:
>>
>> I'll change the above to
>>
>> : syzkaller fuzzer (when using an injected kmalloc failure) found this bug,
>> : that resulted in the following:
>>
>> it's important, because this bug won't be triggered (at all easily, at
>> least) in real-world workloads.
> 
> I wonder if memory-constrained cgroups make such bugs much easier to trigger.
> 

I think you might expose some bugs with memory-constrained cgroups.  However,
it is unlikely you could trigger this bug using that method.

In this bug the injected kmalloc failure was for a 32 byte allocation.  My
guess is that it would be very very unlikely/lucky to have the allocations
done by other routines on the stack succeed, and have this 32 byte allocation
fail.   

-- 
Mike Kravetz