Re: [Qemu-devel] Question: qemu crashed for re-entry of bdrv_drain_recurse

[Stefan Hajnoczi]

On Fri, Feb 09, 2018 at 07:57:42AM +0000, fuweiwei (C) wrote:
> We find a problem of reentrant of bdrv_drain_recurse() of the same bs, which 
> makes
> Qemu assertion failed at
> 
>      assert(!bs_->wakeup);
> 
> in BDRV_POLL_WHILE.
> 
> To construct the problem, we do block-commit job (or others) while filling 
> the space in host
> file-system to make it full. The VM should be automatically paused and at the 
> same time, the
> block-commit job is completed. We get the following stack.
> 
> We can see in #24 calls bdrv_drain_recurse, and polls a bh of 
> commit_complete, which reopen
> the image and calls bdrv_drain_recurse again.
> 
> How to solve this problem?

Thanks for the email.  I have posted a patch and CCed you.  Please test
it and let us know if it solves the issue.

Stefan

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