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Date: Fri, 16 Feb 2018 13:58:48 -0800
From: Matthew Wilcox <willy@infradead.org>
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Subject: Re: [Qemu-devel] [PATCH v21 1/5] xbitmap: Introduce xbitmap
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To: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: Wei Wang <wei.w.wang@intel.com>, virtio-dev@lists.oasis-open.org, Linux Kernel Mailing List <linux-kernel@vger.kernel.org>, qemu-devel@nongnu.org, virtualization@lists.linux-foundation.org, kvm@vger.kernel.org, linux-mm <linux-mm@kvack.org>, "Michael S. Tsirkin" <mst@redhat.com>, mhocko@kernel.org, Andrew Morton <akpm@linux-foundation.org>, Matthew Wilcox <mawilcox@microsoft.com>, david@redhat.com, Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>, cornelia.huck@de.ibm.com, mgorman@techsingularity.net, aarcange@redhat.com, amit.shah@redhat.com, Paolo Bonzini <pbonzini@redhat.com>, liliang.opensource@gmail.com, yang.zhang.wz@gmail.com, quan.xu0@gmail.com, nilal@redhat.com, riel@redhat.com

On Fri, Feb 16, 2018 at 11:45:51PM +0200, Andy Shevchenko wrote:
> Now, the question about test case. Why do you heavily use BUG_ON?
> Isn't resulting statistics enough?

No.  If any of those tests fail, we want to stop dead.  They'll lead to
horrendous bugs throughout the kernel if they're wrong.  I think more of
the in-kernel test suite should stop dead instead of printing a warning.
Would you want to boot a machine which has a known bug in the page cache,
for example?