From mboxrd@z Thu Jan  1 00:00:00 1970
From: bugzilla-daemon@bugzilla.kernel.org
Subject: [Bug 197861] Shutting down a VM with Kernel 4.14 will sometime hang
 and a reboot is the only way to recover.
Date: Wed, 13 Dec 2017 23:09:28 +0000
Message-ID: <bug-197861-28872-olcotvwBm3@https.bugzilla.kernel.org/>
References: <bug-197861-28872@https.bugzilla.kernel.org/>
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https://bugzilla.kernel.org/show_bug.cgi?id=197861

--- Comment #15 from Willem de Bruijn (willemb@google.com) ---
It is quite likely that this patch --or patchset-- is involved, as the hang
happens in cleaning up zerocopy skb state and this patchset extends zerocopy.

Because of conflicts I had to resolve this patch is not a pure revert, but the
changes should be limited to replacing

        uarg->callback(uarg, false);
        skb_shinfo(skb)->tx_flags &= ~SKBTX_DEV_ZEROCOPY;

with an skb_zcopy_clear(skb, false) that boils down to the same.

One option would be to test while reverting the entire patchset. I may be able
to do that, no idea how many conflicts I'd have to resolve.

Perhaps first, could you try the other suggestion with the warnings. If those
fire, then we know for sure that this is implicated.

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