On Fri 04-08-17 17:25:46, Tetsuo Handa wrote:
> Well, while lockdep warning is gone, this problem is remaining.
>
> diff --git a/mm/memory.c b/mm/memory.c
> index edabf6f..1e06c29 100644
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -3931,15 +3931,14 @@ int handle_mm_fault(struct vm_area_struct *vma, unsigned long address,
> /*
> * This mm has been already reaped by the oom reaper and so the
> * refault cannot be trusted in general. Anonymous refaults would
> - * lose data and give a zero page instead e.g. This is especially
> - * problem for use_mm() because regular tasks will just die and
> - * the corrupted data will not be visible anywhere while kthread
> - * will outlive the oom victim and potentially propagate the date
> - * further.
> + * lose data and give a zero page instead e.g.
> */
> - if (unlikely((current->flags & PF_KTHREAD) && !(ret & VM_FAULT_ERROR)
> - && test_bit(MMF_UNSTABLE, &vma->vm_mm->flags)))
> + if (unlikely(!(ret & VM_FAULT_ERROR)
> + && test_bit(MMF_UNSTABLE, &vma->vm_mm->flags))) {
> + if (ret & VM_FAULT_RETRY)
> + down_read(&vma->vm_mm->mmap_sem);
> ret = VM_FAULT_SIGBUS;
> + }
>
> return ret;
> }
I have re-read your email again and I guess I misread previously. Are
you saying that the data corruption happens with the both patches
applied?
>
> $ cat /tmp/file.* | od -b | head
> 0000000 377 377 377 377 377 377 377 377 377 377 377 377 377 377 377 377
> *
> 420330000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000
> *
> 420340000 377 377 377 377 377 377 377 377 377 377 377 377 377 377 377 377
> *
> 457330000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000
> *
> 457340000 377 377 377 377 377 377 377 377 377 377 377 377 377 377 377 377
> *
>
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--
Michal Hocko
SUSE Labs
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