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Date: Fri, 29 Aug 2014 12:49:45 +0300
From: Dan Carpenter <dan.carpenter@oracle.com>
To: KY Srinivasan <kys@microsoft.com>
Cc: Sitsofe Wheeler <sitsofe@gmail.com>, Dexuan Cui <decui@microsoft.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Haiyang Zhang <haiyangz@microsoft.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "devel@linuxdriverproject.org" <devel@linuxdriverproject.org>
Subject: Re: [PANIC, hyperv] BUG: unable to handle kernel paging request at
 ffff880077800004 (hv_ringbuffer_write)
Message-ID: <20140829094945.GA5122@mwanda>
References: <20140820092630.GA1478@sucs.org>
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It's sort of weird that this is an alignment issue.  The config that
was posted earlier was an x86_64 config and on that system then the
pointers from kmalloc() should already be aligned correctly at
sizeof(u64).

Earlier I said I suspected the code is racy, so possibly changing from
kmalloc() to get_zeroed_page() just changes the timing enough so we
don't see the race condition.

regards,
dan carpenter