netdev - Re: [PATCH net] ibmvnic: continue fatal error reset after passive init

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Message-ID: <20201222184615.13ba9cad@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com>
Date:   Tue, 22 Dec 2020 18:46:15 -0800
From:   Jakub Kicinski <kuba@...nel.org>
To:     Lijun Pan <ljp@...ux.ibm.com>
Cc:     netdev@...r.kernel.org
Subject: Re: [PATCH net] ibmvnic: continue fatal error reset after passive
 init

On Sat, 19 Dec 2020 15:40:34 -0600 Lijun Pan wrote:
> Commit f9c6cea0b385 ("ibmvnic: Skip fatal error reset after passive init")
> says "If the passive
> CRQ initialization occurs before the FATAL reset task is processed,
> the FATAL error reset task would try to access a CRQ message queue
> that was freed, causing an oops. The problem may be most likely to
> occur during DLPAR add vNIC with a non-default MTU, because the DLPAR
> process will automatically issue a change MTU request.
> Fix this by not processing fatal error reset if CRQ is passively
> initialized after client-driven CRQ initialization fails."
> 
> Even with this commit, we still see similar kernel crashes. In order
> to completely solve this problem, we'd better continue the fatal error
> reset, capture the kernel crash, and try to fix it from that end.

This basically reverts the quoted fix. Does the quoted fix make things
worse? Otherwise we should leave the code be until proper fix is found.