Re: Multiple potential races on vma->vm_flags

[Andrey Konovalov]

If anybody comes up with a patch to fix the original issue I easily
can test it, since I'm hitting "BUG: Bad page state" in a second when
fuzzing with KTSAN and Trinity.

On Tue, Sep 15, 2015 at 9:01 PM, Kirill A. Shutemov
<kirill@xxxxxxxxxxxxx> wrote:
> On Tue, Sep 15, 2015 at 01:36:45PM -0400, Sasha Levin wrote:
>> On 09/11/2015 09:27 PM, Hugh Dickins wrote:
>> > I'm inclined to echo Vlastimil's comment from earlier in the thread:
>> > sounds like an overkill, unless we find something more serious than this.
>>
>> I've modified my tests to stress the exit path of processes with many vmas,
>
> Could you share the test?
>
>> and hit the following NULL ptr deref (not sure if it's related to the original issue):
>>
>> [1181047.935563] kasan: GPF could be caused by NULL-ptr deref or user memory accessgeneral protection fault: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC KASAN
>> [1181047.937223] Modules linked in:
>> [1181047.937772] CPU: 4 PID: 21912 Comm: trinity-c341 Not tainted 4.3.0-rc1-next-20150914-sasha-00043-geddd763-dirty #2554
>> [1181047.939387] task: ffff8804195c8000 ti: ffff880433f00000 task.ti: ffff880433f00000
>> [1181047.940533] RIP: unmap_vmas (mm/memory.c:1337)
>
> Is it "struct mm_struct *mm = vma->vm_mm;"?
>
> --
>  Kirill A. Shutemov
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